International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Effect of nitrogen on crevice corrosion and repassivationFerRy P. RAzi
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1. The document investigates the effect of nitrogen content on the crevice corrosion and repassivation behavior of austenitic stainless steels.
2. Tests found that increasing nitrogen content decreases corrosion spots, corrosion loss, and maximum corrosion depth during crevice corrosion. Nitrogen stimulates passivation and suppresses crevice corrosion.
3. Surface analysis showed the presence of nitrogen as nitrides and NH3 in the passive film and crevice corrosion areas, which contributes to improved corrosion resistance.
Assessment of the leachability and mechanical stability of mud from a zinc pl...eSAT Publishing House
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This document summarizes a study that examined immobilizing mud from a zinc plating plant and waste zeolite materials with Portland cement. Samples with different proportions of mud and zeolite-mud mixtures were prepared and tested. Leachability was assessed using a modified leaching test, where zinc concentrations in eluates were measured after different time periods. A diffusion model was used to assess zinc diffusion speeds and leaching mechanisms. Mechanical strength tests were also conducted. The study aimed to determine the effectiveness of immobilizing zinc-containing wastes with cement and understand the chemical and physical processes involved.
Surfactant-assisted Hydrothermal Synthesis of Ceria-Zirconia Nanostructured M...IOSR Journals
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CeO2âZrO2 oxides were prepared by the surfactant-templated method using cetyl trimethyl ammonium bromide (CTAB) as template and modified with chromium nitrate. These were characterized by XRD, FT-IR, TEM, SEM, BET and TPD-CO2. The XRD data showed that as prepared CeO2-ZrO2 powder particles have single phase cubic fluorite structure. HRTEM shows mesoscopic ordering. Average particle size is 12-13 nm as calculated from particle histogram. The nitrogen adsorption/desorption isotherm were classified to be type IV isotherm, typical of mesoporous material. The presence of uni-modal mesopores are confirmed by the pore size distribution which shows pore distribution at around 60 A°. Catalytic activity was studied towards liquid-phase oxidation of benzene.
Influence of alkaline substances (carbonates and bicarbonates of sodium) in w...eSAT Publishing House
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IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
This document summarizes an experiment investigating the electrochemical behavior of carbon steel used for nuclear reactor containment buildings. Potentiodynamic, potentiostatic, and galvanostatic polarization techniques were used to study the steel's behavior in Ca(OH)2 solutions with varying NaCl concentrations. It was found that pitting occurred on the steel in solutions above a certain chloride concentration threshold that decreased with increasing chloride levels. Galvanostatic tests determined the chloride threshold conditions for depassivation of the pre-passivated steel. Optical microscopy of polarized samples confirmed localized corrosion above the threshold.
Characterization and Humidity Sensing Application of WO3-SnO2 NanocompositeIOSR Journals
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The document summarizes a study characterizing the humidity sensing properties of tungsten oxide (WO3) doped with tin oxide (SnO2) nanocomposites. WO3-SnO2 nanocomposites were prepared by solid-state reaction and analyzed for their electrical resistance changes with varying humidity levels. The 3% SnO2-doped WO3 sample annealed at 600°C showed the highest average sensitivity of 18.61 MΊ/%RH over a humidity range of 15-95% RH, along with lower hysteresis, less aging effects, and high reproducibility. X-ray diffraction analysis revealed the crystallite size of the sensing elements to be in the range of 11-234 nm
Corrosion Inhibition of Carbon Steel in Chloride and Sulfate SolutionsIJERA Editor
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The document discusses corrosion inhibition of carbon steel in chloride and sulfate solutions. It studies using a combination of dichromate, molybdate, and nitrite inhibitors to provide high corrosion inhibition. Testing involved immersing steel coupons in synthetic solutions with chloride and sulfate ions and measuring corrosion rates. Results found that a combination of 1 ppm sodium dichromate, 250 ppm sodium molybdate, and 50 ppm sodium nitrite provided the best corrosion inhibition while meeting environmental regulations. Further testing examined the effects of changing inhibitor concentrations and environmental parameters like chloride concentration, rotation speed, and pH. The inhibitor combination performed well except being sensitive to increases in sulfate concentration.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Effect of nitrogen on crevice corrosion and repassivationFerRy P. RAzi
Â
1. The document investigates the effect of nitrogen content on the crevice corrosion and repassivation behavior of austenitic stainless steels.
2. Tests found that increasing nitrogen content decreases corrosion spots, corrosion loss, and maximum corrosion depth during crevice corrosion. Nitrogen stimulates passivation and suppresses crevice corrosion.
3. Surface analysis showed the presence of nitrogen as nitrides and NH3 in the passive film and crevice corrosion areas, which contributes to improved corrosion resistance.
Assessment of the leachability and mechanical stability of mud from a zinc pl...eSAT Publishing House
Â
This document summarizes a study that examined immobilizing mud from a zinc plating plant and waste zeolite materials with Portland cement. Samples with different proportions of mud and zeolite-mud mixtures were prepared and tested. Leachability was assessed using a modified leaching test, where zinc concentrations in eluates were measured after different time periods. A diffusion model was used to assess zinc diffusion speeds and leaching mechanisms. Mechanical strength tests were also conducted. The study aimed to determine the effectiveness of immobilizing zinc-containing wastes with cement and understand the chemical and physical processes involved.
Surfactant-assisted Hydrothermal Synthesis of Ceria-Zirconia Nanostructured M...IOSR Journals
Â
CeO2âZrO2 oxides were prepared by the surfactant-templated method using cetyl trimethyl ammonium bromide (CTAB) as template and modified with chromium nitrate. These were characterized by XRD, FT-IR, TEM, SEM, BET and TPD-CO2. The XRD data showed that as prepared CeO2-ZrO2 powder particles have single phase cubic fluorite structure. HRTEM shows mesoscopic ordering. Average particle size is 12-13 nm as calculated from particle histogram. The nitrogen adsorption/desorption isotherm were classified to be type IV isotherm, typical of mesoporous material. The presence of uni-modal mesopores are confirmed by the pore size distribution which shows pore distribution at around 60 A°. Catalytic activity was studied towards liquid-phase oxidation of benzene.
Influence of alkaline substances (carbonates and bicarbonates of sodium) in w...eSAT Publishing House
Â
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
This document summarizes an experiment investigating the electrochemical behavior of carbon steel used for nuclear reactor containment buildings. Potentiodynamic, potentiostatic, and galvanostatic polarization techniques were used to study the steel's behavior in Ca(OH)2 solutions with varying NaCl concentrations. It was found that pitting occurred on the steel in solutions above a certain chloride concentration threshold that decreased with increasing chloride levels. Galvanostatic tests determined the chloride threshold conditions for depassivation of the pre-passivated steel. Optical microscopy of polarized samples confirmed localized corrosion above the threshold.
Characterization and Humidity Sensing Application of WO3-SnO2 NanocompositeIOSR Journals
Â
The document summarizes a study characterizing the humidity sensing properties of tungsten oxide (WO3) doped with tin oxide (SnO2) nanocomposites. WO3-SnO2 nanocomposites were prepared by solid-state reaction and analyzed for their electrical resistance changes with varying humidity levels. The 3% SnO2-doped WO3 sample annealed at 600°C showed the highest average sensitivity of 18.61 MΊ/%RH over a humidity range of 15-95% RH, along with lower hysteresis, less aging effects, and high reproducibility. X-ray diffraction analysis revealed the crystallite size of the sensing elements to be in the range of 11-234 nm
Corrosion Inhibition of Carbon Steel in Chloride and Sulfate SolutionsIJERA Editor
Â
The document discusses corrosion inhibition of carbon steel in chloride and sulfate solutions. It studies using a combination of dichromate, molybdate, and nitrite inhibitors to provide high corrosion inhibition. Testing involved immersing steel coupons in synthetic solutions with chloride and sulfate ions and measuring corrosion rates. Results found that a combination of 1 ppm sodium dichromate, 250 ppm sodium molybdate, and 50 ppm sodium nitrite provided the best corrosion inhibition while meeting environmental regulations. Further testing examined the effects of changing inhibitor concentrations and environmental parameters like chloride concentration, rotation speed, and pH. The inhibitor combination performed well except being sensitive to increases in sulfate concentration.
Characterization of corrosion of x70 pipeline steel in thin electrolyte layerA X.S
Â
This document describes a study that used scanning Kelvin probe technique to characterize the corrosion behavior of X70 pipeline steel in thin layers of near-neutral and high pH solutions. The key findings are:
1) In a thin near-neutral pH solution layer (60 Îźm), passivity could develop on the steel surface due to iron ions reaching saturation, allowing iron carbonate precipitation. Thicker layers inhibited passivation.
2) In thin high pH solution layers, the steel maintained passivity and cathodic reactions were limited by oxygen diffusion. Polarization behavior was independent of layer thickness.
3) Bulk solution tests showed active corrosion in near-neutral pH but passivity in high pH, without cathodic
1991_Sensitivity to Iron Impurity Content of Corrosion Rate of Mg-15Al_Cotton...James D. Cotton
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The corrosion rates of extrusions produced from rapidly-solidified Mg-15wt%AI alloy powder containing varying levels of iron (Fe) impurity (0.003-0.020wt%) were studied. Trace amounts of Fe were found to have a strong exponential effect on the corrosion rate, consistent with previous studies. However, the sensitivity to Fe content was markedly lower for the rapidly-solidified alloys compared to conventionally-cast alloys. This effect is explained by the microstructural refinement produced by rapid solidification, which decreases the scale of microstructure and distributes corrosion more evenly. Both pitting and filiform corrosion were observed and characterized using various microscopy techniques.
IRJET- Synthesis and Characterization of Chromium Oxide Nanoparticles by Chem...IRJET Journal
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The document summarizes research on the synthesis and characterization of chromium oxide nanoparticles using a chemical precipitation method. Chromium sulfate and chromium chloride precursors were used with ammonium hydroxide as the precipitating agent. The nanoparticles were characterized using XRD and UV-Vis spectroscopy. XRD analysis confirmed the formation of hexagonal chromium oxide nanoparticles around 24-27 nm in size. UV-Vis analysis found the bandgap to be approximately 3.7-4.8 eV. The antibacterial properties of the nanoparticles were examined by measuring zones of inhibition for E. coli bacteria, finding zones of 10mm and 8mm for two samples, demonstrating the potential for using chromium oxide nanoparticles as antibacterial agents.
It's a presentation prepared from a paper named "Latest developments on the viscosity of nanofluids." The original paper is an open-source content in ELSEVIER.
IRJET - Electrophoretic Deposition of Calcium phosphate Ceramics over Dup...IRJET Journal
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This document summarizes research on coating calcium phosphate ceramics onto duplex stainless steel using electrophoretic deposition. The coatings of hydroxyapatite (HAp) and tricalcium phosphate (TCP) were characterized. HAp was coated at voltages from 7.5V to 15V and times from 7.5 to 120 minutes. TCP was coated at voltages of 10V, 12.5V and 15V and times of 7.5 to 15 minutes. Coating morphology, composition, and adhesion were analyzed using SEM, EDS, and tape tests. HAp coatings showed different growth structures depending on voltage and time, while TCP coatings adhered best at 10V and 10 minutes. The growth mechanisms
This document presents the results of a neutron reflectometry study investigating the hydration of ultrathin antifouling organosilane adlayers on oxidized silicon wafers. The study finds that for a monoethylene glycol silane adlayer, there exists a relatively thick, continuous transition zone of water stemming from within the adlayer. In contrast, for a less effective adlayer lacking internal ether oxygen atoms, this physically distinct interfacial water phase is much thinner and confined to the adlayer-bulk water interface. These results provide further insight into the link between surface hydration and antifouling properties of organosilane adlayers.
This study analyzed the corrosion of different diameter rebar (12mm and 8mm) in reinforced concrete samples subjected to 231 days of cyclic immersion and drying in simulated marine environment. The 12mm rebar experienced greater mass loss and corrosion rates 61% higher than the 8mm rebar within 182 days. The time to corrosion initiation was predicted using a chloride diffusion model and half-cell potential testing, while time to propagation was estimated using the Maaddawy model. However, the Maaddawy model did not fully account for the higher diffusion rates in immersion cycles, leading to uncertainties. The results suggest using smaller diameter rebar like 8mm for secondary reinforcements and reducing spacing between stirrups to prolong the service
This document is a student research paper investigating the effects of pre-leaching and particle size on copper slag bioleaching. The paper includes an introduction to copper and its production methods, as well as a literature review on factors that can influence bioleaching such as bacterial adaptation, pH, particle size, and pretreatment. The methodology describes shake flask and column experiments testing different pH levels, particle sizes, nitric acid concentrations, and flow rates. The results show that higher pH levels and smaller particle sizes increased copper extraction, and that a mixture of sulfuric and nitric acids was more effective than sulfuric acid alone. The paper concludes by recommending areas for further study.
Catalyst Synthesis by Solvothermal Process (Ghanekar,Deshmukh)_Prof PN Dange-...Gandhar Ghanekar
Â
Iron molybdate catalyst was synthesized using a solvothermal process for photocatalytic applications. Monoclinic and orthorhombic iron(II) molybdate micro-sized particles were selectively prepared based on pH, temperature, and reaction time. The catalyst has unique 3D architectures and can be used to decompose dyes and other organic contaminants photocatalytically. Parameters like pH, concentration, temperature, and time were optimized to produce the catalyst and for its application in degrading methylene blue dye. The catalyst showed potential for scale-up and other industrial applications.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
1) Graphene oxide coatings were deposited on mild steel substrates using electrophoretic deposition. The coatings were characterized using various techniques and their corrosion resistance was evaluated using electrochemical tests.
2) Thermally treated graphene oxide coatings provided better corrosion resistance than bare mild steel, reducing the corrosion rate by about half. This is likely due to the coatings becoming more hydrophobic and developing a denser graphitic structure upon heating.
3) Electrochemical impedance spectroscopy showed that the thermally treated graphene oxide coatings had a higher charge transfer resistance, indicating their ability to act as a barrier against corrosion by limiting the access of corrosive electrolytes to the steel substrate.
Effect of Iron on Some Geotechnical Properties of ClaysIRJET Journal
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This document discusses a study on the effect of iron contamination on the geotechnical properties of two soils - a high plasticity clay (CH) and a low plasticity clay (CL). Tests were conducted by contaminating the soils with various molarities of ferric chloride solution. The results showed that iron contamination tended to initially reduce the liquid limit and plastic limit of the CH clay, but increased them at higher concentrations. For the CL clay, both the liquid limit and plastic limit increased with increasing iron concentration. The permeability of both soils significantly decreased with iron contamination but increased slightly at higher concentrations. In general, iron contamination altered the key geotechnical properties of the soils.
ELECTRO DIALYSIS FOR THE DESALINATION OF BACKWATERS IN KERALAcivej
Â
With the declining freshwater source and increase in demand for the potable water need of desalination
have increased. The electrodialysis can be put as an economic substitute for the desalination of the
brackish water. This paper deals with the assessment of the effect contaminants in the desalination of
natural brackish water using electrodialysis. The contaminants studied were Boron, Sulfate and
Magnesium in the presence of chloride. The study was based on the function of pH at a constant voltage
of 11 V. Magnesium, Chloride, and Sulfate was not affected by the pH variations and was removed to an
efficiency of 94%, 95%, and 74% respectively. But the boron was not removed in neutral pH and showed
a removal efficiency of 41% at pH 10 in an hour. There was significant interference in the removal of the
Chloride ion and Sulfate ion.
This document describes a study that investigated various techniques for preparing a nickel oxide (NiO) catalyst coating on an FeCrAl substrate for use in catalytic converters. Specifically, it examined applying nickel to the substrate through electroplating with and without ultrasonic treatment, and then oxidizing the nickel to form a NiO layer. The techniques aimed to develop an innovative and simpler method for adhering catalyst powder to the substrate. The study assessed the techniques based on weight gain during oxidation testing and analyzed the resulting oxide growth and microstructure.
Study the rheological and mechanical properties of pva cu cl2 by ultrasonicAlexander Decker
Â
The document studies the rheological and mechanical properties of polyvinyl alcohol (PVA) solutions with the addition of copper (II) chloride (CuCl2). PVA solutions were prepared with varying amounts of CuCl2 added. Ultrasonic measurements were taken to analyze properties including density, viscosity, velocity, bulk modulus, compressibility, transmittance, absorption coefficient, and relaxation amplitude. The results showed that adding CuCl2 increased viscosity and absorption coefficient, which decreased velocity, bulk modulus, and transmittance. This is because more CuCl2 molecules in solution lead to greater attenuation of ultrasonic waves. Overall, the intermolecular interactions between PVA and CuCl2 influenced the rhe
This project aimed to develop graphene oxide (GO) membranes for water filtration by synthesizing GO flakes using two Hummer's methods, characterizing the flakes, selecting a substrate, depositing GO on it, and testing salt rejection. Polyethersulfone (PES) was chosen as the substrate. The second synthesis method yielded more oxidized and amorphous GO flakes based on characterization. GO was deposited on plasma-treated PES using a dead-end cell. Diffusion testing found the homemade GO membrane rejected 75.6% of salts compared to 94.2% for a commercial membrane, demonstrating potential for economical water treatment.
Equivalent Dielectric property of hydrogenated carbon nitride film in CH4/N2 ...inventionjournals
Â
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
- The document examines the corrosion behavior of API 5L X42 carbon steel samples immersed in sodium chloride (NaCl) and sodium carbonate (Na2CO3) solutions of different concentrations (0.5M and 1.0M) for 1008 hours.
- Experimental results showed the highest corrosion occurred in the 1.0M Na2CO3 solution, as this environment did not form a protective film on the steel samples. The next highest corrosion was in the 0.5M NaCl solution.
- Generally, corrosion rates were higher in environments like Na2CO3 that do not form protective oxide films, and increased with higher concentrations. Corrosion was lower in environments like NaCl that can form
67551071 au-gold cementation with zinc powder at low cyanidesalarislideshare
Â
The document summarizes an electrochemical study of gold cementation with zinc powder at low cyanide concentrations in alkaline solutions. Key findings include:
1) Gold reduction in low cyanide concentration solutions is greatly influenced by strong adsorptive processes rather than diffusion of Au(CN)2- complexes as in high cyanide solutions.
2) Zinc oxidation is controlled by the formation of different passivating layers on the zinc surface depending on pH.
3) Mixed potentials and currents determined from Evans' diagrams do not adequately describe the global cementation reaction due to the strong influence of adsorption at low cyanide concentrations. Direct monitoring of the mixed potential using zinc powder electrodes was proposed instead.
This document provides tips on winning government and private tenders, outlining strategies like advance planning, tailoring submissions, understanding evaluation criteria, and demonstrating an understanding of the scope, risks, and ability to deliver the project on budget. Common mistakes to avoid include non-compliance, failure to show capability or comprehension of the work. Resources for finding tender opportunities include websites like Austender, paid search services, and directly contacting local governments.
How to Remove System Progressive Protection - Removal InstructionsAdriano Day
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The document provides instructions for removing the System Progressive Protection virus, which is a fake antivirus program that disguises itself as legitimate security software. It describes how the virus installs itself and tricks users into believing their computer is infected in order to get them to pay a fee. The summary then outlines the step-by-step process for manually removing the virus in safe mode, including stopping processes, deleting files and registry entries, and provides a video guide. It cautions that the virus may block removal tools so contacting a technician for help may be needed.
Characterization of corrosion of x70 pipeline steel in thin electrolyte layerA X.S
Â
This document describes a study that used scanning Kelvin probe technique to characterize the corrosion behavior of X70 pipeline steel in thin layers of near-neutral and high pH solutions. The key findings are:
1) In a thin near-neutral pH solution layer (60 Îźm), passivity could develop on the steel surface due to iron ions reaching saturation, allowing iron carbonate precipitation. Thicker layers inhibited passivation.
2) In thin high pH solution layers, the steel maintained passivity and cathodic reactions were limited by oxygen diffusion. Polarization behavior was independent of layer thickness.
3) Bulk solution tests showed active corrosion in near-neutral pH but passivity in high pH, without cathodic
1991_Sensitivity to Iron Impurity Content of Corrosion Rate of Mg-15Al_Cotton...James D. Cotton
Â
The corrosion rates of extrusions produced from rapidly-solidified Mg-15wt%AI alloy powder containing varying levels of iron (Fe) impurity (0.003-0.020wt%) were studied. Trace amounts of Fe were found to have a strong exponential effect on the corrosion rate, consistent with previous studies. However, the sensitivity to Fe content was markedly lower for the rapidly-solidified alloys compared to conventionally-cast alloys. This effect is explained by the microstructural refinement produced by rapid solidification, which decreases the scale of microstructure and distributes corrosion more evenly. Both pitting and filiform corrosion were observed and characterized using various microscopy techniques.
IRJET- Synthesis and Characterization of Chromium Oxide Nanoparticles by Chem...IRJET Journal
Â
The document summarizes research on the synthesis and characterization of chromium oxide nanoparticles using a chemical precipitation method. Chromium sulfate and chromium chloride precursors were used with ammonium hydroxide as the precipitating agent. The nanoparticles were characterized using XRD and UV-Vis spectroscopy. XRD analysis confirmed the formation of hexagonal chromium oxide nanoparticles around 24-27 nm in size. UV-Vis analysis found the bandgap to be approximately 3.7-4.8 eV. The antibacterial properties of the nanoparticles were examined by measuring zones of inhibition for E. coli bacteria, finding zones of 10mm and 8mm for two samples, demonstrating the potential for using chromium oxide nanoparticles as antibacterial agents.
It's a presentation prepared from a paper named "Latest developments on the viscosity of nanofluids." The original paper is an open-source content in ELSEVIER.
IRJET - Electrophoretic Deposition of Calcium phosphate Ceramics over Dup...IRJET Journal
Â
This document summarizes research on coating calcium phosphate ceramics onto duplex stainless steel using electrophoretic deposition. The coatings of hydroxyapatite (HAp) and tricalcium phosphate (TCP) were characterized. HAp was coated at voltages from 7.5V to 15V and times from 7.5 to 120 minutes. TCP was coated at voltages of 10V, 12.5V and 15V and times of 7.5 to 15 minutes. Coating morphology, composition, and adhesion were analyzed using SEM, EDS, and tape tests. HAp coatings showed different growth structures depending on voltage and time, while TCP coatings adhered best at 10V and 10 minutes. The growth mechanisms
This document presents the results of a neutron reflectometry study investigating the hydration of ultrathin antifouling organosilane adlayers on oxidized silicon wafers. The study finds that for a monoethylene glycol silane adlayer, there exists a relatively thick, continuous transition zone of water stemming from within the adlayer. In contrast, for a less effective adlayer lacking internal ether oxygen atoms, this physically distinct interfacial water phase is much thinner and confined to the adlayer-bulk water interface. These results provide further insight into the link between surface hydration and antifouling properties of organosilane adlayers.
This study analyzed the corrosion of different diameter rebar (12mm and 8mm) in reinforced concrete samples subjected to 231 days of cyclic immersion and drying in simulated marine environment. The 12mm rebar experienced greater mass loss and corrosion rates 61% higher than the 8mm rebar within 182 days. The time to corrosion initiation was predicted using a chloride diffusion model and half-cell potential testing, while time to propagation was estimated using the Maaddawy model. However, the Maaddawy model did not fully account for the higher diffusion rates in immersion cycles, leading to uncertainties. The results suggest using smaller diameter rebar like 8mm for secondary reinforcements and reducing spacing between stirrups to prolong the service
This document is a student research paper investigating the effects of pre-leaching and particle size on copper slag bioleaching. The paper includes an introduction to copper and its production methods, as well as a literature review on factors that can influence bioleaching such as bacterial adaptation, pH, particle size, and pretreatment. The methodology describes shake flask and column experiments testing different pH levels, particle sizes, nitric acid concentrations, and flow rates. The results show that higher pH levels and smaller particle sizes increased copper extraction, and that a mixture of sulfuric and nitric acids was more effective than sulfuric acid alone. The paper concludes by recommending areas for further study.
Catalyst Synthesis by Solvothermal Process (Ghanekar,Deshmukh)_Prof PN Dange-...Gandhar Ghanekar
Â
Iron molybdate catalyst was synthesized using a solvothermal process for photocatalytic applications. Monoclinic and orthorhombic iron(II) molybdate micro-sized particles were selectively prepared based on pH, temperature, and reaction time. The catalyst has unique 3D architectures and can be used to decompose dyes and other organic contaminants photocatalytically. Parameters like pH, concentration, temperature, and time were optimized to produce the catalyst and for its application in degrading methylene blue dye. The catalyst showed potential for scale-up and other industrial applications.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
1) Graphene oxide coatings were deposited on mild steel substrates using electrophoretic deposition. The coatings were characterized using various techniques and their corrosion resistance was evaluated using electrochemical tests.
2) Thermally treated graphene oxide coatings provided better corrosion resistance than bare mild steel, reducing the corrosion rate by about half. This is likely due to the coatings becoming more hydrophobic and developing a denser graphitic structure upon heating.
3) Electrochemical impedance spectroscopy showed that the thermally treated graphene oxide coatings had a higher charge transfer resistance, indicating their ability to act as a barrier against corrosion by limiting the access of corrosive electrolytes to the steel substrate.
Effect of Iron on Some Geotechnical Properties of ClaysIRJET Journal
Â
This document discusses a study on the effect of iron contamination on the geotechnical properties of two soils - a high plasticity clay (CH) and a low plasticity clay (CL). Tests were conducted by contaminating the soils with various molarities of ferric chloride solution. The results showed that iron contamination tended to initially reduce the liquid limit and plastic limit of the CH clay, but increased them at higher concentrations. For the CL clay, both the liquid limit and plastic limit increased with increasing iron concentration. The permeability of both soils significantly decreased with iron contamination but increased slightly at higher concentrations. In general, iron contamination altered the key geotechnical properties of the soils.
ELECTRO DIALYSIS FOR THE DESALINATION OF BACKWATERS IN KERALAcivej
Â
With the declining freshwater source and increase in demand for the potable water need of desalination
have increased. The electrodialysis can be put as an economic substitute for the desalination of the
brackish water. This paper deals with the assessment of the effect contaminants in the desalination of
natural brackish water using electrodialysis. The contaminants studied were Boron, Sulfate and
Magnesium in the presence of chloride. The study was based on the function of pH at a constant voltage
of 11 V. Magnesium, Chloride, and Sulfate was not affected by the pH variations and was removed to an
efficiency of 94%, 95%, and 74% respectively. But the boron was not removed in neutral pH and showed
a removal efficiency of 41% at pH 10 in an hour. There was significant interference in the removal of the
Chloride ion and Sulfate ion.
This document describes a study that investigated various techniques for preparing a nickel oxide (NiO) catalyst coating on an FeCrAl substrate for use in catalytic converters. Specifically, it examined applying nickel to the substrate through electroplating with and without ultrasonic treatment, and then oxidizing the nickel to form a NiO layer. The techniques aimed to develop an innovative and simpler method for adhering catalyst powder to the substrate. The study assessed the techniques based on weight gain during oxidation testing and analyzed the resulting oxide growth and microstructure.
Study the rheological and mechanical properties of pva cu cl2 by ultrasonicAlexander Decker
Â
The document studies the rheological and mechanical properties of polyvinyl alcohol (PVA) solutions with the addition of copper (II) chloride (CuCl2). PVA solutions were prepared with varying amounts of CuCl2 added. Ultrasonic measurements were taken to analyze properties including density, viscosity, velocity, bulk modulus, compressibility, transmittance, absorption coefficient, and relaxation amplitude. The results showed that adding CuCl2 increased viscosity and absorption coefficient, which decreased velocity, bulk modulus, and transmittance. This is because more CuCl2 molecules in solution lead to greater attenuation of ultrasonic waves. Overall, the intermolecular interactions between PVA and CuCl2 influenced the rhe
This project aimed to develop graphene oxide (GO) membranes for water filtration by synthesizing GO flakes using two Hummer's methods, characterizing the flakes, selecting a substrate, depositing GO on it, and testing salt rejection. Polyethersulfone (PES) was chosen as the substrate. The second synthesis method yielded more oxidized and amorphous GO flakes based on characterization. GO was deposited on plasma-treated PES using a dead-end cell. Diffusion testing found the homemade GO membrane rejected 75.6% of salts compared to 94.2% for a commercial membrane, demonstrating potential for economical water treatment.
Equivalent Dielectric property of hydrogenated carbon nitride film in CH4/N2 ...inventionjournals
Â
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
- The document examines the corrosion behavior of API 5L X42 carbon steel samples immersed in sodium chloride (NaCl) and sodium carbonate (Na2CO3) solutions of different concentrations (0.5M and 1.0M) for 1008 hours.
- Experimental results showed the highest corrosion occurred in the 1.0M Na2CO3 solution, as this environment did not form a protective film on the steel samples. The next highest corrosion was in the 0.5M NaCl solution.
- Generally, corrosion rates were higher in environments like Na2CO3 that do not form protective oxide films, and increased with higher concentrations. Corrosion was lower in environments like NaCl that can form
67551071 au-gold cementation with zinc powder at low cyanidesalarislideshare
Â
The document summarizes an electrochemical study of gold cementation with zinc powder at low cyanide concentrations in alkaline solutions. Key findings include:
1) Gold reduction in low cyanide concentration solutions is greatly influenced by strong adsorptive processes rather than diffusion of Au(CN)2- complexes as in high cyanide solutions.
2) Zinc oxidation is controlled by the formation of different passivating layers on the zinc surface depending on pH.
3) Mixed potentials and currents determined from Evans' diagrams do not adequately describe the global cementation reaction due to the strong influence of adsorption at low cyanide concentrations. Direct monitoring of the mixed potential using zinc powder electrodes was proposed instead.
This document provides tips on winning government and private tenders, outlining strategies like advance planning, tailoring submissions, understanding evaluation criteria, and demonstrating an understanding of the scope, risks, and ability to deliver the project on budget. Common mistakes to avoid include non-compliance, failure to show capability or comprehension of the work. Resources for finding tender opportunities include websites like Austender, paid search services, and directly contacting local governments.
How to Remove System Progressive Protection - Removal InstructionsAdriano Day
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The document provides instructions for removing the System Progressive Protection virus, which is a fake antivirus program that disguises itself as legitimate security software. It describes how the virus installs itself and tricks users into believing their computer is infected in order to get them to pay a fee. The summary then outlines the step-by-step process for manually removing the virus in safe mode, including stopping processes, deleting files and registry entries, and provides a video guide. It cautions that the virus may block removal tools so contacting a technician for help may be needed.
Le slides del seminario âVQR: Maneggiare con curaâ tenuto a Pavia il 9 ottobre 2013 da Giuseppe De Nicolao
Abstract. LâANVUR ha da poco concluso un esercizio nazionale di valutazione della ricerca, la VQR 2004-2010. Nonostante le grandi aspettative riposte in tale valutazione, non sono mancate le controversie, riassumibili lungo tre direzioni principali: la comunicazione dei risultati sotto forma di classifiche, lâadeguatezza della metodologia scientifica e la tendenza dellâANVUR a travalicare un ruolo meramente tecnico. Per mettere nella giusta prospettiva il dibattito, è bene far riferimento allo stato dellâarte della letteratura scientometrica e allâesperienza di altre agenzie di valutazione, come per esempio lâHEFCE inglese. Un approccio scientifico è altrettanto necessario per valutare se i risultati della VQR possano essere impiegati â e con quali caveat â nella ripartizione delle risorse allâinterno degli atenei.
Totally R*-Continuous and Totally R*-Irresolute Functionsinventionjournals
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International Journal of Mathematics and Statistics Invention (IJMSI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJMSI publishes research articles and reviews within the whole field Mathematics and Statistics, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
An Improved Regression Type Estimator of Finite Population Mean using Coeffic...inventionjournals
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International Journal of Mathematics and Statistics Invention (IJMSI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJMSI publishes research articles and reviews within the whole field Mathematics and Statistics, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
Inventory Model with Different Deterioration Rates with Stock and Price Depen...inventionjournals
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International Journal of Mathematics and Statistics Invention (IJMSI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJMSI publishes research articles and reviews within the whole field Mathematics and Statistics, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
International Journal of Mathematics and Statistics Invention (IJMSI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJMSI publishes research articles and reviews within the whole field Mathematics and Statistics, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
This document discusses probabilistic diameter and its properties. It defines probabilistic diameter (DA) as a distribution function that represents the probability that the distance between any two points in a set A is less than some value t. It presents several properties of probabilistic diameter including: (1) DA is a distribution function; (2) DA = H if A contains a single point; and (3) if A is a subset of B, then DA ⼠DB. It also defines probabilistic distance between two sets A and B as another distribution function (FAB) and establishes some of its properties.
International Journal of Mathematics and Statistics Invention (IJMSI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJMSI publishes research articles and reviews within the whole field Mathematics and Statistics, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
International Journal of Mathematics and Statistics Invention (IJMSI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJMSI publishes research articles and reviews within the whole field Mathematics and Statistics, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
On Estimation of Population Variance Using Auxiliary Informationinventionjournals
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International Journal of Mathematics and Statistics Invention (IJMSI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJMSI publishes research articles and reviews within the whole field Mathematics and Statistics, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
The Effect of Stirring Rate on Electrodeposition of Nanocrystalline Nickel Co...Kaveh Rahimi Mamaghani
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Nanocrystalline pure nickel coating was electroplated on pure copper by means of a modified Watts bath with variant stirring rates and current densities. The crystallite sizes were calculated by XRD analysis. The crystallite size had an inverse relation with stirring rate and current density in the plating bath. The best corrosion resistance was observed in 5 A/dm2 current density of polarization test and corrosion rate smoothly increased by agitation in the plating bath. The microstructure evolution at high stirring rates exhibited some surface bubbles that affected the surface quality and properties. Although Vickers microhardness increased by the addition of the current density, our measurements showed that the hardness had an inverse relationship with turbulence in the solution. An optimum agitation in the bath could improve the hardness distribution on the coated specimen. However, specimens with agitation did not follow the HallâPetch relationship between crystallite size and microhardness.
Effects of Different Parameters on Molybdenum Concentration in Zn MO Mn Alloyijtsrd
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Molybdenum is an active metal possessing high degree of corrosion resistance, hardness, high conduction along with magnetic properties. Alloy containing Zinc, Molybdenum and Manganese have been studied in this paper. The change in properties due to change in temperature, pH and current density, duration of deposition and concentration of Molybdenum in electrolytic solution were the basis of experiments conducted in this paper. The electrolytic concentration and current density produce complimentary effects to a large extent. Effect of various parameters specified above on the concentration of Molybdenum in Zn Mn MO alloy have been studied in this paper. Renu Rastogi "Effects of Different Parameters on Molybdenum Concentration in Zn-MO-Mn Alloy" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-7 | Issue-3 , June 2023, URL: https://www.ijtsrd.com.com/papers/ijtsrd57394.pdf Paper URL: https://www.ijtsrd.com.com/chemistry/physical-chemistry/57394/effects-of-different-parameters-on-molybdenum-concentration-in-znmomn-alloy/renu-rastogi
This document summarizes an experiment on using electrocoagulation with iron electrodes to remove mercury from wastewater. Key findings include:
1) Maximum mercury removal of 94.5% was achieved after 40 minutes of electrocoagulation at an applied potential of 9V, agitation of 400 rpm, initial pH of 4.5, and electrolyte concentration of 1.333 g/L.
2) Higher applied potentials and agitation rates decreased mercury removal efficiency due to excessive oxygen generation and unsuitable floc formation.
3) Operating costs were calculated based on energy consumption and electrode material costs. Electrocoagulation was found to be an efficient and fast method for mercury removal compared to conventional techniques.
Comparative Study on Strength Enhancement of Concrete using Magnetic and Norm...ijtsrd
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Water performs an essential function in concrete preparation and additionally in workability and power of the concrete. The big quantity of salt and mineral content is existing in regular water. It leads to affect the sturdiness of concrete shape and also life spans of shape are reduced. One of the recent technologies used to enhance the compressive strength and workability of concrete is using magnetized water as a substitute of ordinary water in concrete mixes. This new technological know how has increased the compressive strength. Using magnetized water in concrete is fantastic in terms of decrease porosity and higher. In this technology, by using passing water through a magnetic field, the range of molecules in the water cluster is breakdown into small from 13 to 5 or 6, which reasons a decrease in the surface tension of water and also expand the pH and reduces the hardness in the water with an improvement in the workability and power of concrete. Due to the smaller measurement of molecules, the water layer surrounding the cement is thinner than normal water molecules. These initiatives are examined to compare the power of normal water and magnetized water in concrete. The discount of the quantity of salt and mineral content in water will improve resistance to corrosion excessively. In this study, the effect of magnetic water and regular water on workability and power of M30 grade concrete was studied and comparative observation for NWC and MWC by means of compression strength and spit tensile strength. K. Swathi | T. Sathieshkumar "Comparative Study on Strength Enhancement of Concrete using Magnetic and Normal Water" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-4 | Issue-3 , April 2020, URL: https://www.ijtsrd.com/papers/ijtsrd30638.pdf Paper Url :https://www.ijtsrd.com/engineering/civil-engineering/30638/comparative-study-on-strength-enhancement-of-concrete-using-magnetic-and-normal-water/k-swathi
Today, the ion exchange method is widely used in water treatment systems. Ion exchange systems are used to correct the mineral composition of water to the required standards; wastewater treatment; desalination and softening of natural waters. To present day, there are technical solutions to improve the process of water purification, treatment, softening and demineralization. They include: improvement of physical and chemical conditions; intensification of the ion exchange process; use of new ion exchange materials; modification of ion exchange resins; combination with other water treatment methods; modernization of equipment and designs of ion exchange devices. In order to improve the flow conditions and reduce the burden on the environment, it is promising to implement technologies aimed at intensifying the ion exchange process by activating the components of the process. The paper investigates the effect of magnetic modification on the intensification of ion exchange processes during the adjustment of the mineral composition of natural waters. The obtained results demonstrate the influence of the magnetic field on the ion exchange process.
Kinetic modelling of nitrate removal from aqueous solution during electrocoag...Alexander Decker
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This document discusses a study that aimed to model nitrate removal from aqueous solutions using electrocoagulation. Experiments were conducted to treat a synthetic solution containing 150 mg/L of nitrate using iron electrodes under various conditions. Kinetic and adsorption models were tested to determine which best fit the nitrate removal data. The results showed pseudo-second order kinetics and the Freundlich isotherm provided the best fits. Nitrate removal efficiency increased with reaction time and current density.
This document summarizes research on electrodepositing silver nanoparticles onto carbon sphere surfaces using a pulse current. Key findings include:
1) Silver nanoparticles were successfully electrodeposited with a size of 100-400nm after 2 minutes using a pulse current.
2) Deposition occurred on accessible carbon surface sites, forming a monolayer of scattered nanoparticles. Continued deposition led to larger particles and multilayers.
3) Pulse current helped manage monolayer deposition compared to direct current, controlling particle size and number of layers.
This document summarizes research on the effect of electrokinetics processes on minerals and molecules of expansive clay. Testing with XRD and SEM was conducted before and after electrokinetics processing using lime solution. XRD results showed that the electrokinetics process did not change the types of clay minerals present. SEM images indicated the presence of white traces on clay molecules after electrokinetics, suggesting lime was deposited on clay particles through cation exchange during the process. The research demonstrated the potential for electrokinetics to be developed as an alternative method for stabilizing expansive clays.
This document provides an overview of electrocoagulation (EC) as a wastewater treatment process. It describes the basic EC process, which uses sacrificial anode dissolution to introduce metal ions into water that destabilize pollutants. Key factors that affect EC efficiency are discussed, including electrode arrangement, current density, pH, and electrode material. The document also outlines several applications of EC for treating various types of industrial wastewaters and waters containing pollutants like heavy metals, dyes, and organic matter. EC is presented as an effective wastewater treatment alternative that is simple to operate and can remove a wide range of pollutants.
This document summarizes an article about electrocoagulation as a novel wastewater treatment method. Electrocoagulation uses sacrificial metal anodes that corrode when electric current is applied, producing metal cations that neutralize pollutants in water. It has advantages over other methods in providing coagulants without increasing water salinity. The document discusses the mechanisms of electrocoagulation including coagulant production, pollutant destabilization, and aggregation. Key factors like electrode material, current density, and operating conditions affect the process's performance in removing various pollutants from water.
This document describes research into using alkaline zinc hydroxide solution as an electrolyte for hydrogen generation through water electrolysis. The solution is prepared by dissolving zinc oxide in sodium hydroxide or potassium hydroxide solutions, forming sodium zincate or potassium zincate. Experimental results showed that using these solutions as electrolytes can enhance the hydrogen evolution rate compared to conventional electrolytes. Specifically, sodium zincate increased the rate by a factor of 2.74 and potassium zincate by 1.47. The zincate solutions may improve ionic conductivity and electrode catalytic activity for hydrogen evolution. This research could help optimize alkaline water electrolysis systems for more efficient hydrogen production.
Magnesium carbonate trihydrate, nesquehonite, is proposed as a precursor for the production of a construction material similar to plasterboard,
in a unique carbon capture and utilisation process [1]. The hardening process is thought to follow a similar mechanism to gypsum in the manufacture
of plasterboard, where the hardening is produced in the recrystallization of gypsum crystals. However, nesquehonite [2], during hardening,
converts into hydromagnesite, releasing CO2
and H2
O during the transformation. In this work, samples of nesquehonite were hardened by forcing
their conversion into hydromagnesite in enclosed cubes [3]. The influence of the curing temperature (50 â-80 â) and time (0-72 hours) on the
compressive strength has been studied and correlated to the conversion of nesquehonite into hydromagnesite [4]. Compressive strength values up
to 6MPa are easily achievable in the studied conditions and it was observed that at higher temperatures time has a detrimental effect on the strength.
The probable overpressure within the cubes, generated by released CO2
and water at the higher temperatures, is thought to be the main cause for
the loss of strength [5].
A new technique to measure oxygen reduction kinetics underneath coatings using hydrogen permeation from the back side. Huge step towards characterising buried interface reactivity.
Removal of 137Cs from contaminated soil using pilot electrokinetic decontamin...Agriculture Journal IJOEAR
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âThe removal efficiencies of 137Cs for 10 days were 50-70%. The removal efficiencies according to the elapsed time after 10 days were reduced. When an electric current density of 25-75 mA/cm2, sulfuric acid, nitric acid, acetic acid as electrolyte, a 0.5-2.0 cm/min hydraulic conductivity of soil were applied, respectively, the time required for the removal efficiency of 137Cs to reach 80% was 20-30 days. For improving removal efficiency of 137Cs from contaminated soil, it is necessary to increase an electric current density using sulfuric acid as an electrolyte and to decrease hydraulic conductivity of soil in the soil cell.
IRJET- Carburizing of Plane Carbon Steels by Electrolyte PlasmaIRJET Journal
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This document discusses plasma electrolytic carburizing of mild steel (ASTM A-36) to improve its surface properties. Mild steel samples were carburized in a solution of glycerin, ammonium chloride and water at 400°C for times ranging from 5 to 10 minutes. Longer carburization times resulted in thicker carburized layers with higher microhardness. The microstructure of the carburized layers consisted of martensite with finer grain sizes for longer treatment times. Plasma electrolytic carburizing decreased the wear rate and surface roughness of the mild steel samples.
This document summarizes research on using electrodeposited manganese dioxide (MnO2) coatings on porous carbon substrates for capacitive deionization (CDI) applications. Two carbon substrates with different surface areas and morphologies were coated with MnO2 using galvanostatic and cyclic voltammetric deposition. Characterization of the coated electrodes found mixed MnO2 phases present. Testing in half-cell configurations showed that maximum ion uptake per mass was not necessarily optimal for practical CDI applications, where performance per electrode area is more important. The results suggest the structure and deposition method can impact how effectively the electrode volume participates in ion removal reactions.
IRJET- Carburizing of Plane Carbon Steels by Electrolyte PlasmaIRJET Journal
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This document summarizes research on carburizing plain carbon steels through electrolyte plasma. Specifically, it examines carburizing ASTM A-36 steel (mild steel) using a plasma electrolytic carburizing process in a glycerin and ammonium chloride solution. The experiment involved applying a DC voltage to generate plasma around steel specimens submerged in the electrolyte for 5-10 minutes at 400°C. Analysis found the carburized layers averaged 3.4 Οm and 5.7 Οm thick for 5- and 10-minute samples, with average microhardness of 210 HV and 228 HV. Increased voltage resulted in more carbon deposition on specimens' surfaces and higher microhardness.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Electrochemical investigations on the inhibition behaviorAliKarimi127
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This document discusses the corrosion inhibition properties of di(Resacetophenone) 1,2 cyclohexandiimine (R DACH) Schiff base on steel in 1 M HCl solution. Electrochemical measurements including potentiodynamic polarization, electrochemical impedance spectroscopy, and chronoamperometry were used to evaluate the inhibition efficiency of R DACH at different concentrations and temperatures. The results showed that R DACH is an effective corrosion inhibitor for steel, with inhibition efficiency increasing with increasing concentration. Adsorption of the inhibitor followed the Langmuir isotherm. Activation energy and thermodynamic parameters like enthalpy, entropy, and Gibbs free energy of adsorption were calculated from corrosion currents at different temperatures and
This document summarizes a study that investigated how operational parameters influence the bright nickel plating process. The study found that the weight of bright nickel deposited was affected by plating temperature, voltage, current density, pH, and plating time. The best bright nickel deposition was obtained at 56°C, a current density of 6 A/dm2, and a plating time of 18 minutes. The document provides details on the experimental setup and procedures, including the composition of the nickel plating bath and operating conditions that were tested. Results are presented showing correlations between temperature and current density, and the effect of operational parameters on nickel deposition.
"Choosing proper type of scaling", Olena SyrotaFwdays
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Imagine an IoT processing system that is already quite mature and production-ready and for which client coverage is growing and scaling and performance aspects are life and death questions. The system has Redis, MongoDB, and stream processing based on ksqldb. In this talk, firstly, we will analyze scaling approaches and then select the proper ones for our system.
How information systems are built or acquired puts information, which is what they should be about, in a secondary place. Our language adapted accordingly, and we no longer talk about information systems but applications. Applications evolved in a way to break data into diverse fragments, tightly coupled with applications and expensive to integrate. The result is technical debt, which is re-paid by taking even bigger "loans", resulting in an ever-increasing technical debt. Software engineering and procurement practices work in sync with market forces to maintain this trend. This talk demonstrates how natural this situation is. The question is: can something be done to reverse the trend?
QA or the Highway - Component Testing: Bridging the gap between frontend appl...zjhamm304
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These are the slides for the presentation, "Component Testing: Bridging the gap between frontend applications" that was presented at QA or the Highway 2024 in Columbus, OH by Zachary Hamm.
In the realm of cybersecurity, offensive security practices act as a critical shield. By simulating real-world attacks in a controlled environment, these techniques expose vulnerabilities before malicious actors can exploit them. This proactive approach allows manufacturers to identify and fix weaknesses, significantly enhancing system security.
This presentation delves into the development of a system designed to mimic Galileo's Open Service signal using software-defined radio (SDR) technology. We'll begin with a foundational overview of both Global Navigation Satellite Systems (GNSS) and the intricacies of digital signal processing.
The presentation culminates in a live demonstration. We'll showcase the manipulation of Galileo's Open Service pilot signal, simulating an attack on various software and hardware systems. This practical demonstration serves to highlight the potential consequences of unaddressed vulnerabilities, emphasizing the importance of offensive security practices in safeguarding critical infrastructure.
"NATO Hackathon Winner: AI-Powered Drug Search", Taras KlobaFwdays
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This is a session that details how PostgreSQL's features and Azure AI Services can be effectively used to significantly enhance the search functionality in any application.
In this session, we'll share insights on how we used PostgreSQL to facilitate precise searches across multiple fields in our mobile application. The techniques include using LIKE and ILIKE operators and integrating a trigram-based search to handle potential misspellings, thereby increasing the search accuracy.
We'll also discuss how the azure_ai extension on PostgreSQL databases in Azure and Azure AI Services were utilized to create vectors from user input, a feature beneficial when users wish to find specific items based on text prompts. While our application's case study involves a drug search, the techniques and principles shared in this session can be adapted to improve search functionality in a wide range of applications. Join us to learn how PostgreSQL and Azure AI can be harnessed to enhance your application's search capability.
The Microsoft 365 Migration Tutorial For Beginner.pptxoperationspcvita
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This presentation will help you understand the power of Microsoft 365. However, we have mentioned every productivity app included in Office 365. Additionally, we have suggested the migration situation related to Office 365 and how we can help you.
You can also read: https://www.systoolsgroup.com/updates/office-365-tenant-to-tenant-migration-step-by-step-complete-guide/
The Department of Veteran Affairs (VA) invited Taylor Paschal, Knowledge & Information Management Consultant at Enterprise Knowledge, to speak at a Knowledge Management Lunch and Learn hosted on June 12, 2024. All Office of Administration staff were invited to attend and received professional development credit for participating in the voluntary event.
The objectives of the Lunch and Learn presentation were to:
- Review what KM âisâ and âisnâtâ
- Understand the value of KM and the benefits of engaging
- Define and reflect on your âwhatâs in it for me?â
- Share actionable ways you can participate in Knowledge - - Capture & Transfer
Lee Barnes - Path to Becoming an Effective Test Automation Engineer.pdfleebarnesutopia
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So⌠you want to become a Test Automation Engineer (or hire and develop one)? While thereâs quite a bit of information available about important technical and tool skills to master, thereâs not enough discussion around the path to becoming an effective Test Automation Engineer that knows how to add VALUE. In my experience this had led to a proliferation of engineers who are proficient with tools and building frameworks but have skill and knowledge gaps, especially in software testing, that reduce the value they deliver with test automation.
In this talk, Lee will share his lessons learned from over 30 years of working with, and mentoring, hundreds of Test Automation Engineers. Whether youâre looking to get started in test automation or just want to improve your trade, this talk will give you a solid foundation and roadmap for ensuring your test automation efforts continuously add value. This talk is equally valuable for both aspiring Test Automation Engineers and those managing them! All attendees will take away a set of key foundational knowledge and a high-level learning path for leveling up test automation skills and ensuring they add value to their organizations.
From Natural Language to Structured Solr Queries using LLMsSease
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This talk draws on experimentation to enable AI applications with Solr. One important use case is to use AI for better accessibility and discoverability of the data: while User eXperience techniques, lexical search improvements, and data harmonization can take organizations to a good level of accessibility, a structural (or âcognitiveâ gap) remains between the data user needs and the data producer constraints.
That is where AI â and most importantly, Natural Language Processing and Large Language Model techniques â could make a difference. This natural language, conversational engine could facilitate access and usage of the data leveraging the semantics of any data source.
The objective of the presentation is to propose a technical approach and a way forward to achieve this goal.
The key concept is to enable users to express their search queries in natural language, which the LLM then enriches, interprets, and translates into structured queries based on the Solr indexâs metadata.
This approach leverages the LLMâs ability to understand the nuances of natural language and the structure of documents within Apache Solr.
The LLM acts as an intermediary agent, offering a transparent experience to users automatically and potentially uncovering relevant documents that conventional search methods might overlook. The presentation will include the results of this experimental work, lessons learned, best practices, and the scope of future work that should improve the approach and make it production-ready.
Must Know Postgres Extension for DBA and Developer during MigrationMydbops
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Mydbops Opensource Database Meetup 16
Topic: Must-Know PostgreSQL Extensions for Developers and DBAs During Migration
Speaker: Deepak Mahto, Founder of DataCloudGaze Consulting
Date & Time: 8th June | 10 AM - 1 PM IST
Venue: Bangalore International Centre, Bangalore
Abstract: Discover how PostgreSQL extensions can be your secret weapon! This talk explores how key extensions enhance database capabilities and streamline the migration process for users moving from other relational databases like Oracle.
Key Takeaways:
* Learn about crucial extensions like oracle_fdw, pgtt, and pg_audit that ease migration complexities.
* Gain valuable strategies for implementing these extensions in PostgreSQL to achieve license freedom.
* Discover how these key extensions can empower both developers and DBAs during the migration process.
* Don't miss this chance to gain practical knowledge from an industry expert and stay updated on the latest open-source database trends.
Mydbops Managed Services specializes in taking the pain out of database management while optimizing performance. Since 2015, we have been providing top-notch support and assistance for the top three open-source databases: MySQL, MongoDB, and PostgreSQL.
Our team offers a wide range of services, including assistance, support, consulting, 24/7 operations, and expertise in all relevant technologies. We help organizations improve their database's performance, scalability, efficiency, and availability.
Contact us: info@mydbops.com
Visit: https://www.mydbops.com/
Follow us on LinkedIn: https://in.linkedin.com/company/mydbops
For more details and updates, please follow up the below links.
Meetup Page : https://www.meetup.com/mydbops-databa...
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Blogs: https://www.mydbops.com/blog/
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As AI technology is pushing into IT I was wondering myself, as an âinfrastructure container kubernetes guyâ, how get this fancy AI technology get managed from an infrastructure operational view? Is it possible to apply our lovely cloud native principals as well? What benefitâs both technologies could bring to each other?
Let me take this questions and provide you a short journey through existing deployment models and use cases for AI software. On practical examples, we discuss what cloud/on-premise strategy we may need for applying it to our own infrastructure to get it to work from an enterprise perspective. I want to give an overview about infrastructure requirements and technologies, what could be beneficial or limiting your AI use cases in an enterprise environment. An interactive Demo will give you some insides, what approaches I got already working for real.
Keywords: AI, Containeres, Kubernetes, Cloud Native
Event Link: https://meine.doag.org/events/cloudland/2024/agenda/#agendaId.4211
Essentials of Automations: Exploring Attributes & Automation ParametersSafe Software
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Building automations in FME Flow can save time, money, and help businesses scale by eliminating data silos and providing data to stakeholders in real-time. One essential component to orchestrating complex automations is the use of attributes & automation parameters (both formerly known as âkeysâ). In fact, itâs unlikely youâll ever build an Automation without using these components, but what exactly are they?
Attributes & automation parameters enable the automation author to pass data values from one automation component to the next. During this webinar, our FME Flow Specialists will cover leveraging the three types of these output attributes & parameters in FME Flow: Event, Custom, and Automation. As a bonus, theyâll also be making use of the Split-Merge Block functionality.
Youâll leave this webinar with a better understanding of how to maximize the potential of automations by making use of attributes & automation parameters, with the ultimate goal of setting your enterprise integration workflows up on autopilot.
What is an RPA CoE? Session 1 â CoE VisionDianaGray10
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In the first session, we will review the organization's vision and how this has an impact on the COE Structure.
Topics covered:
⢠The role of a steering committee
⢠How do the organizationâs priorities determine CoE Structure?
Speaker:
Chris Bolin, Senior Intelligent Automation Architect Anika Systems
What is an RPA CoE? Session 2 â CoE RolesDianaGray10
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In this session, we will review the players involved in the CoE and how each role impacts opportunities.
Topics covered:
⢠What roles are essential?
⢠What place in the automation journey does each role play?
Speaker:
Chris Bolin, Senior Intelligent Automation Architect Anika Systems
Conversational agents, or chatbots, are increasingly used to access all sorts of services using natural language. While open-domain chatbots - like ChatGPT - can converse on any topic, task-oriented chatbots - the focus of this paper - are designed for specific tasks, like booking a flight, obtaining customer support, or setting an appointment. Like any other software, task-oriented chatbots need to be properly tested, usually by defining and executing test scenarios (i.e., sequences of user-chatbot interactions). However, there is currently a lack of methods to quantify the completeness and strength of such test scenarios, which can lead to low-quality tests, and hence to buggy chatbots.
To fill this gap, we propose adapting mutation testing (MuT) for task-oriented chatbots. To this end, we introduce a set of mutation operators that emulate faults in chatbot designs, an architecture that enables MuT on chatbots built using heterogeneous technologies, and a practical realisation as an Eclipse plugin. Moreover, we evaluate the applicability, effectiveness and efficiency of our approach on open-source chatbots, with promising results.
1. International Journal of Engineering Science Invention
ISSN (Online): 2319 â 6734, ISSN (Print): 2319 â 6726
www.ijesi.org Volume 2 Issue 8 Ç August. 2013 Ç PP.17-24
www.ijesi.org 17 | Page
A Study of Process Parameters for Zinc Electrodeposition from a
Sulphate Bath
T. J. Tuaweri âŤ,Ů⏠E. M. Adigio and P. P. Jombo
Department of Mechanical/Marine Engineering, Niger Delta University,
Wilberforce Island, Amassoma, Bayelsa State, Nigeria
ABSTRACT: Investigation of process parameters for the electrodeposition of zinc has been carried out using
direct current. Cathode current efficiency and deposit thickness were determined by weight measurement
method. Influence of current density on the deposition process was also investigated. Bath agitation and
cathodic polarisation measurements were used to study the mass transport conditions of the electrolytic bath.
Scanning Electron Microscope and Field Emission Gun Scanning Electron Microscopes were utilised to study
the morphologies of the deposits. Effect of temperature on the deposition process and deposit morphology was
also studied. It was observed that cathode current efficiency (CCE%) was dependent on the current density and
bath temperature, while deposit thickness was dependent on current density, bath agitation and time.
Temperature and pH changes had marked influence on the morphology of the deposits. Cathodic polarisation
studies revealed that bath agitation and composition had significant effect on the limiting current density and
hence mass transport of the bath.
KEYWORDS: Zinc, Eletrodeposition, Morphology, Sulphate bath, Cathode polarisation, masstransport.
I. INTRODUCTION
Zinc has found widespread use as the basis of a whole range of sacrificial coatings for ferrous
substrates [1]. It is the most commonly used sacrificial coating [2] and can be applied by a variety of techniques,
including hot- dipping, metal spraying, cementation, cladding and electrode position [1]. The corrosion
characteristics are strongly determined by the texture and microstructure obtained, which in turn depends on the
specific deposition procedure employed. The role of electroplating parameters on the formation of different
textures and microstructures is well established by several researchers [3] using various approaches, which has
effectively lead to the preparation of coatings that differ in their macro and micro-structure, texture density,
uniformity and corrosion resistance [4,5]. Also, it is reported [6] that electrodeposited filmsâ texture, apart from
the corrosion behaviour, can noticeably affect a variety of properties such as paintability, formability and wear
resistance.
A wide variety of plating bath composition has been employed in electrogalvanizing to control the
growth of cathode deposits, inhibiting the formation of dendrites and to produce fine-grained, smoother deposits
[7]. Electrode position yields grain sizes in the nanometer range when variables such as bath composition, pH,
temperature, current density, etc are chosen such that nucleation of new grains is favoured rather than growth of
existing grains [2]. Many of the acid type baths utilise zinc sulphate and are normally used to electroplate cast
iron and malleable irons. The main disadvantages of the acid type baths are that they are corrosive so care has to
be taken to protect operators and equipment and these baths generally exhibit poor current efficiency.
Electroplating normally takes place under a DC regime, however, improved smoothness by means of
pulse plating, a periodically interrupted process in which a certain duty cycle of cathodic potential/current is
employed [6, 8, 9]. Velinov et al [10] found that in the zinc electrocrystallization process two types of
inhibition occur, primary and secondary (autoinhibition). They reported that the conditions for cathode deposit
formation and consequently crystallite orientation are significantly altered by hydrogen codischarge. In general,
the crystalline forms and crystal orientation of metal deposit result from a competition between growth parallel
and perpendicular to the deposition substrate, both determined by supersaturation (expressed by cathodic
overvoltage), which characterises the process in a complicated manner [7]. A high âoutâ growth rate normal to
the substrate leads to a fibrous structure whilst an increased rate of lateral growth may lead to the development
of large âfacetsâ parallel to the substrate.
The effect of zinc and acid concentration on current efficiency has been reported [11]. According to the
authors, increasing the zinc concentration (decreasing the acid concentration) increased the current efficiency in
a non-linear fashion and that the highest rate of increase occurred when the zinc concentration was increased
from 42 to 50 g/l. This was attributed to increase in zinc deposition reaction rate as the number of zinc ions in
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the electrolyte rises. Also, since the number of H+
ions in solution decreases, the rate of hydrogen evolution
reaction is reduced. Both of these factors improve the current efficiency [11]. Indicators of an excellent
electrode position bath includes; good current efficiency and throwing power, longevity of the bath, minimal
hydrogen evolution, etc. This work therefore seeks to investigate the process parameters suitable for the bath in
question to produced zinc electrodeposits with good sacrificial protective properties.
EXPERIMENTAL METHODS AND MATERIALS
1.1 Bath Preparation
Zinc was electrodeposited from additive-free, aqueous solutions composed of standard laboratory
reagents. 0.5 litres of deionised water was poured into a beaker and the reagent was added gradually with mild
agitation initially and then more vigorously, to enhance dissolution. Measurements of pH were carried out using
a HI-8424 digital pH meter, and adjusted accordingly using sodium hydroxide (10 % solution) or concentrated
sulphuric acid. The solution was finally made up to 1 litre by adding more water. The whole process was carried
out at room temperature (approximately 22o
C). The bath formulation is as follows:
Acid zinc [12] 250 g/l ZnSO4.7H2O
80 g/l Na2SO4
pH = 2.0-4.4
2.2 Determination of Cathode Current Efficiency and Deposit Thickness
Cathode current efficiency and deposit thickness were measured gravimetrically. Pre-weighed samples
after plating were first rinsed immediately in running tap water, immersed in acetone, dried in a stream of warm
air and then weighed again to determine the weight gain. Cathode current efficiency and deposit thickness were
subsequently calculated using the following formulae:
Cathode Current efficiency (CCE) =
TW
Wď
Ă 100% 1
Where,
CCE â Cathode current efficiency (%)
ÎW â Change in weight after plating (g)
WT - Theoretical weight of deposit (g)
Whilst;
WT =
Fn
MtI Zn
ď´
ď´ď´
2
Where I = Current (A)
t = Time (second)
MZn = Molecular weight of zinc (g/mol)
F = Faradays const (96,500 C/mol)
n = Number of electrons involved in the reaction
2.3 Cathodic Polarisation Studies
Cathodic polarisation studies were conducted for zinc using an ACM Instruments computer controlled
potentiostat, model Auto Tafel HP, linked to a personal computer. Each test was carried out on a panel blanked
off with chemically inert tape to expose an area of 10 cm2
(2.5 cm x 4 cm). The counter electrode material was
platinum. Each of these different sets of polarisation studies was conducted in order to obtain mechanistic data
for metal deposition. The volume of electrolyte was 350 ml.
Two bath compositions were utilized to investigate the mass transport behaviour of zinc
electrodeposition and are given below:
Bath 1- 10 g/l ZnSO4.7H2O
Bath 2- 250 g/l ZnSO4.7H2O
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RESULTS AND DISCUSSIONS
3.1 Effect of Agitation
The use of bath agitation is intended to improve the mass transport in the electrolyte and therefore
enhance the rate of deposition. However, in terms of cathode current efficiency, bath agitation was found to
reduce the current efficiency with increase in agitation. Figure 1 shows that current efficiency of the bath was
better without or at lower rates of solution agitation at a constant current density of 5 A/dm2. Since the main
reactions at the cathode during electrode position is a competition between zinc reduction and hydrogen
evolution, as the limiting current density is approached during zinc deposition, the zinc ion concentration near
the cathode is quickly depleted and the cathode reaction shifts from zinc deposition to hydrogen evolution.
Figure 1 Effect of Bath Agitation on the Cathode Current Efficiency of the Bath at a Current Density of 5
A/dm2
, pH 2.8 and T= 22 o
C.
This could result in the deposition of a mixture of zinc and zinc hydroxide or zinc oxides [13] due to
pH increase in the vicinity of the cathode. Also, it is noteworthy that agitation could depolarise the hydrogen
evolution reaction and possibly reduce the nucleation rate of zinc on the surface of the cathode. Moreover, the
applied current is shared between two processes: zinc deposition and hydrogen evolution [14, 15]. Since the
hydrogen over potential and hence evolution in this bath was quite high as was observed during the electrode
position process, the main cathode reaction would have been hydrogen evolution. This could be detrimental to
zinc deposition as adsorbed hydrogen on the surface of the cathode could hinder zinc nucleation. This could
mean a higher current density may be needed to drive zinc deposition. But then, at higher current densities, a
larger driving force is required to effect zinc deposition due to possible rise in both anode and cathode potentials
with increase in current density [16]. Generally, an improvement in cathode current efficiency with agitation is
due to the fact that, agitation helps to prevent the adsorption of evolved hydrogen, which usually sits on the
surface of the cathode thereby preventing zinc reduction. The formation of hydrogen bubbles destroyed
periodically by stirring the diffuse layer makes it possible for zinc replenishment [14]. As the hydrogen bubbles
are swept away, a larger surface area on the cathode becomes available periodically for the deposition of zinc
which ordinarily should lead to improved zinc deposition and hence current efficiency. However, this does not
appear to be the case in the present investigations. A possible reason could be that agitation was too vigorous to
allow sufficient residence time for zinc ions to be reduced on the surface of the cathode. This means, agitation
may have been detrimental to the zinc nucleation process in the prevalent conditions.
3.2 Effect of Current Density and Time on Deposit Thickness
In an attempt to optimise conditions for the production of 8 Îźm thick zinc electrodeposits, a range of
current densities were investigated. In each case, maintaining a constant quantity of electricity supplied was
crucial to obtain uniform deposit thickness in all the samples. Visually acceptable coatings were obtained within
the current density range of 2.0-5.0 A/dm2
.
The experimental results in table 1 show that current density is inversely proportional to time to obtain
the same deposit thickness. Increase in current density is accompanied by a decrease in deposition time to obtain
8 Îźm and vice versa. This is consistent with expectations since at higher current densities, the rate of deposition
and deposit build-up is faster. On the contrary, low deposition current densities are associated with small
nucleation rates so the layer thickness has to be large enough in order to cover the whole surface of the substrate
[6]. This invariably means that lower current densities require longer durations to obtain a particular deposit
thickness whilst higher current densities are required to produce the same deposit thickness at a shorter duration.
Therefore, for each current density there is corresponding time duration for the production of 8 Îźm thick
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electrodeposits. Possible exceptions would be when either the bath chemistry or other electrodeposition
parameters are modified to either enhance or reduce the nucleation and hence deposition rate or reduce/remove
reactions in the vicinity of the cathode that are detrimental to metal deposition.
Table 1 Results of the effect of current density and time on the deposit thickness. Bath pH 2.6.
Sample Agitation (rpm) Current density (A/dm2
) Deposit thickness (Âľm) Time (min.)
27 800 2 8.0 14
27.1 0 2 8.0 14
28 800 2.5 8.0 11
28.1 0 2.5 8.0 11
29 800 3.5 8.0 8
29.1 0 3.5 8.0 8
30 800 4 8.0 7
30.1 0 4 8.0 7
The effect of current density on cathode current efficiency is presented in Figure 2. Changes in current
efficiency of the bath appear to be insignificant over a range of current densities between 2.5-4.5 A/dm2
. This is
an indication that there was negligible mass transfer resistance or concentration over potential for the range of
current densities. Similar observations were reported by Scott et al [16] over a current density range of 100-650
A/m2
.
Figure 2 Effect of Current Density on the Cathode Current Efficiency of the Bath at Agitation Rate of 300 rpm,
pH 2, Deposition Time 10 min, T= 22 o
C
However, with further increase in current density, the current efficiency decreased significantly. This is
attributed to increase in hydrogen evolution [2].
3.3 Effect of pH
Figure 3 shows that for the range of pH from 2.5-5.0, the cathode current efficiency increased with
increase in pH. Similar observations have been reported by other investigators [5] that a decrease of the pH
leads to a decrease of the current efficiency. Also in agreement with [3], it can be seen from figures 1, 2, and 3
that majority of current efficiency results produced at pH< 4 shows current efficiencies of less than 100%.
However, in Figure 3, at pH> 4 almost all current efficiencies were greater than 100%. A number of reasons
may be responsible for current efficiency to be greater than 100%. Apart from the possibility of excellent
deposition conditions in the bath, a key reason could be the formation and subsequent codeposition of zinc
oxide and hydroxide . It appears, at higher pH values, the formation and consequent codeposition of ZnO and
Zn(OH)2 probably occurred due to hydrogen evolution with a resultant increase in pH within the vicinity of the
cathode.
Figure 3 Effect of pH on the CCE of the Bath at a Current Density of 5 A/dm2
, Agitation 400 rpm,
Deposition time 6 min., T = 22 o
C
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3.4 Effect of temperature
Influence of temperature on CCE shows an increasing linear relationship. This is obvious from Figure
4 as increase in bath temperature from 30 to 40 o
C was accompanied by a corresponding increase in the CCE
from 96.0% to 97.4%. Similarly, Scott et al reported [16] that current efficiency increased with increase in
temperature from 94.0% at 25 o
C to 97.7% at 50 o
C with a resultant decrease in energy consumption.
Figure 4 Influence of Bath Temperature on the CCE of the Bath at a Current Density of 3 A/dm2
,
Agitation 800 rpm, pH 2.6.
The decrease in energy consumption was attributed to increase in current efficiency and a decrease in
cell voltage as the temperature rises. At higher temperatures the rate constants of both cathodic reactions
increase hence a lower driving force is required [16]. The conductivity of an electrolyte increases with increase
in temperature and this is often more pronounced at higher acid concentrations [11].
3.5 Morphological changes
Surface morphologies of zinc electrodeposits are presented in Figures 5-7. Since zinc occurs in only
one (hexagonal) crystalline form, the morphological features usually observed (moss, sponge, platelets,
boulders) must originate from different arrangements of hexagonal units [17]. The predominant crystallographic
orientations reported on zinc electrodeposits produced from acid sulphate baths without additives are usually the
randomly preferred orientations. Deposit properties of zinc are largely dependent on the texture and surface
morphology of the electrodeposits. A typical surface morphology of zinc produced from the bath is shown in
Figure 5. These morphologies can be tailored with changes in electrodeposition parameters such as current
density, temperature, pH, hydrodynamics of catholyte flow [18], impurities and the presence of certain
additives.
Figure 5 SEM Micrograph of Zinc Electrodeposit from the Bath at a Current Density of 3 A/dm2
,
Agitation 800 rpm and pH 2.6.
3.6 Morphological changes with pH
Electrodeposits were produced with pH variation in the range of 2.6-5.0 at a current density of 3
A/dm2
. Such variations had no significant effect on the thickness of the electrodeposits. However, pH changes
seem to have some effect on the morphology and preferred orientation of the electrodeposits. As can be seen
from Figure 5 deposits obtained from a solution of pH 2.6 generally consisted of zinc platelets with the usual
random orientations associated with zinc electrodeposits from acid sulphate baths. However, at a higher pH
value of about 5, the morphological features changed slightly from those observed at pH 2.6. Figure 6 shows
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that the random orientation initially observed in Figure 5 seems to have transformed to more of a combination of
lateral stacking sequence of zinc crystals and zinc platelets aligned almost perpendicular to the cathode.
Figure 6 SEM Micrograph of Zinc Electrodeposit from the Acid Bath at a Current Density of 3 A/dm2
,
agitation 800 rpm and pH 5
3.7 Morphological changes with temperature
Increase in temperature was observed to have some effect on the crystal orientation of the deposit. With
increasing temperature, the lateral stacking sequence of crystal orientation appears to have transformed from the
usually random orientations (see Figure 5) to that with the edges of the crystals perpendicular to the surface of
the substrate (see Figures 7 and 8). Also, at about 35 o
C, onset of white patches was noticed as particles on the
edges of zinc crystal (see Figure 7). As the temperature increased to 40 o
C, the white patches became
conspicuous on the surface of the deposit as obvious in Figure 8. The observed improvement in cathode current
efficiency with increase in temperature as earlier mentioned and shown in Figure 4 is probably as a result of
such growths and consequent incorporation in the electrodeposits thereby increasing the weight gain and hence
cathode current efficiency values.
Figure 7 SEM Micrograph of Zinc Electrodeposit Produced at a Current Density of 3 A/dm2
,
Agitation 800 rpm, pH 2, T = 35 o
C.
Figure 8 SEM Micrograph of Zinc Electrodeposit Produced at a Current Density of 3 A/dm2
,
Agitation 800 rpm, pH 2, T = 40 o
C.
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3.8 Cathodic polarisation studies
Cathodic polarisation studies were carried out on mild steel to aid a mechanistic understanding of zinc
electrodeposition. Mild steel panels were polarised from their open circuit potential. Both dilute and
concentrated baths were used. Dilute electrolytes were employed in order to achieve well-defined deposition
behaviour in the polarisation curves as opposed to solutions with high zinc levels where metal reduction peaks
are less clear [19].
Figure 9 shows a pair of cathodic polarization curves from the dilute bath and another pair from the
concentrated bath both with and without agitation. It is obvious from this figures that current density increased
for all the investigations carried out in the presence of bath agitation. It appears zinc deposition did not occur
until the potential was about â1130 mV vs. SCE. A gradual increase, depending on the concentration of Zn2+
,
with steep activation is
Figure 9 Cathodic polarisation of zinc baths containing 250 g/l ZnSO4.7H2O (A) agitation (B) Without agitation.
Bath with 10 g/l ZnSO4.7H2O (C) without agitation (D) agitation.
Then observed in a short range of potential and then diffusion control appears to take over at higher
potential values. However, for the investigations without agitation, the zinc deposition current appears to be
very low. This is an indication that for the bath compositions and deposition conditions investigated here,
agitation was favourable for the zinc deposition reaction due to enhanced mass transport. Similar improvements
in mass transport and hence zinc deposition current densities have previously been reported [4].
CONCLUSIONS
Cathode current efficiency and deposit thickness were generally dependent on current density, agitation and
bath temperature. Solution agitation was slightly detrimental to the current efficiency of the bath. Temperature
and pH had marked influence on the deposition process. At higher temperatures, patches of white deposits
thought to be oxides of zinc were observed.
For similar deposit thicknesses, plating time was inversely proportional to current density.
Cathodic polarisation studies revealed that bath agitation had significant effect on the limiting current density
and hence mass transport of the bath.
Acknowledgements
The authors wish to thank the sponsors of this project, Bayelsa State Government of Nigeria
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