The document summarizes research on the erosion-corrosion behavior of WC-Co-Cr cermet coatings applied by thermal spraying. Experiments were conducted exposing the coatings to a liquid-solid jet of 3.5% NaCl solution with silica sand loadings of 200 and 500 mg/l. Electrochemical measurements and surface analysis using SEM were used to understand the corrosion and erosion damage mechanisms. Cathodic protection was applied to isolate the erosion effects. The results showed the WC-Co-Cr coating had higher resistance to erosion-corrosion compared to stainless steel controls. Microstructural characterization revealed the coating had a lamellar structure and composition of WC-12% Co-6% Cr with
This literature review summarizes several studies on slurry erosion performance and resistance of various coated and treated steels. Several studies investigated the effect of parameters like particle size, speed, concentration, and impact angle on erosion rate. Coatings like WC-Co, Cr2O3, and Al2O3 were found to improve erosion resistance compared to uncoated steels. Laser surface treatments using powders also increased hardness and erosion resistance. Erosion mechanisms for coated materials included cracking and removal of material, while uncoated steels experienced plastic deformation and cutting.
An Experimental Investigation on Effect of Elevated Temperatures on M35 grade...IJERD Editor
In the event of sudden fire break out, the concrete elements such as columns, beams etc. are
subjected to extreme temperatures. The assessment of their performance after fire becomes necessary to decide
upon its fitness and required repair measures. Hence, it is important to understand the changes in the concrete
properties due to its exposure to extreme temperatures. It is important to know the effect of elevated temperature
on the properties of concrete. In this project thesis work experimental investigation is carried out to study the
effects of elevated temperatures on the compressive strength of normal concrete and on concrete by partial
replacement of cement with various percentages of fly ash. In the present study a concrete mix M35 and is taken.
In the normal concrete, cement is replaced with (0, 5, 10, 15, 20 and 25%) fly ash.The compressive strength of
concrete with various percentages of fly ash (0%to 25%) are subjected to temperatures (400 to 6000C), for
different time periods (30 and 60min) which were tested for 28 days and 56 days of curing. The samples are
cured in water and later exposed to various temperatures with various time periods. After heating the samples in
electrical furnace to the desired temperatures .They are allowed to cool to the room temperatures and tested
under compression. The average of the readings obtained is recorded and presented in various tables. This study
shows that the compressive strength of fly ash (0%to 10%) concrete is more than the normal concrete at room
temperatures and elevated temperatures and also compared to compressive strength of fly ash (15%to 25%)
concrete.
Comparison of fatigue parameters of alkali activated and ordinary portland ce...eSAT Publishing House
This document compares the fatigue parameters of alkali-activated concrete and ordinary Portland cement concrete. It presents results of static and cyclic fatigue tests on both materials. Under static testing, the compressive strength of alkali-activated concrete was measured over time up to 90 days. Under cyclic fatigue testing, the stress versus number of cycles to failure (S-N curves) were obtained for both concretes in three-point bending tests. The alkali-activated concrete showed a flatter S-N curve with many specimens surviving over 2 million cycles even at high stresses, indicating better fatigue resistance compared to ordinary Portland cement concrete. The results were discussed in terms of using the different concrete types in fatigue-prone applications.
Corrosion Measursement, Friction testing and XRD Analysis of Single Layer CrN...IJAEMSJORNAL
The purpose of present study was to investigate the erosive corrosive wear behavior of single layer (CrN) coatings on AISI 304 Stainless Steel samples with varying coating thickness (0-200 nm) in the range of 50 nm. The slurry jet erosive test was conducted on Slurry Jet Erosion Tester in saline slurry (3.5wt% salt) under the different working conditions with varying impact velocity (10-25 m/s), impingement angle (30°-75°) and erodent discharge (160-280 gm/min). Corrosion tests were conducted in 3.5 wt. % NaCl solution using a Potentiostat, in order to analyze the corrosion behavior of the coated samples in sea water environment. Coefficient of friction was measured using a Scratch Tester. XRD analysis of the eroded samples indicated the presence of both CrN and Cr2N (200) in the coatings.
EROSION PROTECTION OF PULVERIZED BOILER COAL PREPARATION EQUIPMENTMilos Djukic
This document summarizes research on erosion protection materials for pulverized coal preparation equipment in fossil fuel power plants. Samples were tested with different erosion protection materials applied, including two metal alloy coatings applied via cold spraying and one alloy applied via weld overlay. Following erosion testing, the samples were analyzed to compare erosion damage profiles and weight loss. Microstructural analysis found that the weld overlay sample showed the best erosion resistance for the given test conditions, with the cold spray coatings also demonstrating good bonding quality to the substrate. Further testing is needed to determine the best erosion protection methods for different equipment and operating conditions.
Taguchi analysis of single layer CrN coatings on AISI 304 Stainless Steel to ...IJAEMSJORNAL
This document summarizes a study investigating the erosive corrosive wear behavior of single layer chromium nitride (CrN) coatings on AISI 304 stainless steel samples. Taguchi analysis was used to test coated and uncoated samples under varying impact velocity, impingement angle, and erodent discharge. The results showed that CrN coatings reduced the wear rate by nearly 2 times compared to uncoated samples. Taguchi analysis identified that among coated samples, erodent discharge was the most significant factor affecting wear rate, followed by coating thickness and impingement angle, with impact velocity being the least significant. For uncoated samples, impact velocity was the most significant factor. The optimum parameters for minimum wear rate
Surface modification to improve friction and gallingBrunocss
This document summarizes a study that investigated different surface modification techniques for reducing galling in forming tools used on austenitic stainless steel. The techniques included plasma nitriding with different gas mixtures, PVD coatings of TiN and WC/C, and polishing to different surface roughnesses. Tribological testing found that plasma nitriding and polishing improved galling properties compared to untreated tool steel. A WC/C coating significantly reduced friction and galling, but some coating spallation occurred under dry conditions. Finer polishing to a roughness of Ra=0.05 μm provided the best galling resistance, with little material transfer even at high loads. The study suggests a combination of nitriding, pol
The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
This literature review summarizes several studies on slurry erosion performance and resistance of various coated and treated steels. Several studies investigated the effect of parameters like particle size, speed, concentration, and impact angle on erosion rate. Coatings like WC-Co, Cr2O3, and Al2O3 were found to improve erosion resistance compared to uncoated steels. Laser surface treatments using powders also increased hardness and erosion resistance. Erosion mechanisms for coated materials included cracking and removal of material, while uncoated steels experienced plastic deformation and cutting.
An Experimental Investigation on Effect of Elevated Temperatures on M35 grade...IJERD Editor
In the event of sudden fire break out, the concrete elements such as columns, beams etc. are
subjected to extreme temperatures. The assessment of their performance after fire becomes necessary to decide
upon its fitness and required repair measures. Hence, it is important to understand the changes in the concrete
properties due to its exposure to extreme temperatures. It is important to know the effect of elevated temperature
on the properties of concrete. In this project thesis work experimental investigation is carried out to study the
effects of elevated temperatures on the compressive strength of normal concrete and on concrete by partial
replacement of cement with various percentages of fly ash. In the present study a concrete mix M35 and is taken.
In the normal concrete, cement is replaced with (0, 5, 10, 15, 20 and 25%) fly ash.The compressive strength of
concrete with various percentages of fly ash (0%to 25%) are subjected to temperatures (400 to 6000C), for
different time periods (30 and 60min) which were tested for 28 days and 56 days of curing. The samples are
cured in water and later exposed to various temperatures with various time periods. After heating the samples in
electrical furnace to the desired temperatures .They are allowed to cool to the room temperatures and tested
under compression. The average of the readings obtained is recorded and presented in various tables. This study
shows that the compressive strength of fly ash (0%to 10%) concrete is more than the normal concrete at room
temperatures and elevated temperatures and also compared to compressive strength of fly ash (15%to 25%)
concrete.
Comparison of fatigue parameters of alkali activated and ordinary portland ce...eSAT Publishing House
This document compares the fatigue parameters of alkali-activated concrete and ordinary Portland cement concrete. It presents results of static and cyclic fatigue tests on both materials. Under static testing, the compressive strength of alkali-activated concrete was measured over time up to 90 days. Under cyclic fatigue testing, the stress versus number of cycles to failure (S-N curves) were obtained for both concretes in three-point bending tests. The alkali-activated concrete showed a flatter S-N curve with many specimens surviving over 2 million cycles even at high stresses, indicating better fatigue resistance compared to ordinary Portland cement concrete. The results were discussed in terms of using the different concrete types in fatigue-prone applications.
Corrosion Measursement, Friction testing and XRD Analysis of Single Layer CrN...IJAEMSJORNAL
The purpose of present study was to investigate the erosive corrosive wear behavior of single layer (CrN) coatings on AISI 304 Stainless Steel samples with varying coating thickness (0-200 nm) in the range of 50 nm. The slurry jet erosive test was conducted on Slurry Jet Erosion Tester in saline slurry (3.5wt% salt) under the different working conditions with varying impact velocity (10-25 m/s), impingement angle (30°-75°) and erodent discharge (160-280 gm/min). Corrosion tests were conducted in 3.5 wt. % NaCl solution using a Potentiostat, in order to analyze the corrosion behavior of the coated samples in sea water environment. Coefficient of friction was measured using a Scratch Tester. XRD analysis of the eroded samples indicated the presence of both CrN and Cr2N (200) in the coatings.
EROSION PROTECTION OF PULVERIZED BOILER COAL PREPARATION EQUIPMENTMilos Djukic
This document summarizes research on erosion protection materials for pulverized coal preparation equipment in fossil fuel power plants. Samples were tested with different erosion protection materials applied, including two metal alloy coatings applied via cold spraying and one alloy applied via weld overlay. Following erosion testing, the samples were analyzed to compare erosion damage profiles and weight loss. Microstructural analysis found that the weld overlay sample showed the best erosion resistance for the given test conditions, with the cold spray coatings also demonstrating good bonding quality to the substrate. Further testing is needed to determine the best erosion protection methods for different equipment and operating conditions.
Taguchi analysis of single layer CrN coatings on AISI 304 Stainless Steel to ...IJAEMSJORNAL
This document summarizes a study investigating the erosive corrosive wear behavior of single layer chromium nitride (CrN) coatings on AISI 304 stainless steel samples. Taguchi analysis was used to test coated and uncoated samples under varying impact velocity, impingement angle, and erodent discharge. The results showed that CrN coatings reduced the wear rate by nearly 2 times compared to uncoated samples. Taguchi analysis identified that among coated samples, erodent discharge was the most significant factor affecting wear rate, followed by coating thickness and impingement angle, with impact velocity being the least significant. For uncoated samples, impact velocity was the most significant factor. The optimum parameters for minimum wear rate
Surface modification to improve friction and gallingBrunocss
This document summarizes a study that investigated different surface modification techniques for reducing galling in forming tools used on austenitic stainless steel. The techniques included plasma nitriding with different gas mixtures, PVD coatings of TiN and WC/C, and polishing to different surface roughnesses. Tribological testing found that plasma nitriding and polishing improved galling properties compared to untreated tool steel. A WC/C coating significantly reduced friction and galling, but some coating spallation occurred under dry conditions. Finer polishing to a roughness of Ra=0.05 μm provided the best galling resistance, with little material transfer even at high loads. The study suggests a combination of nitriding, pol
The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
Review on Erosion and Corrosion Studies on Steel WeldmentsIRJET Journal
This document provides an extensive literature review on erosion and corrosion studies carried out on various grades of steel weldments. It discusses different types of erosion and corrosion, parameters that affect erosion rates like particle size and impact angle. Methods to analyze erosion and corrosion rates like weight loss tests and SEM imaging are also summarized. The review focuses on erosion and corrosion behavior of carbon steels like A106 grade steel typically used in pipes under various environmental conditions like chemicals and high temperatures.
An equiaxed, submicron grain size distribution was generated in an Al (0.1 wt.% Sc) alloy by
processing through equal channel angular pressing followed by a low temperature pre-
ageing heat treatment. The alloy was subsequently annealed for various times at 300, 350,
400 and 450° C for investigating the thermal stability of the deformation microstructure. It
was found that up to 400° C, the submicron grain structure coarsens slowly and uniformly by
a process of continuous recrystallization.
Influence of phase transformation on the work hardening characteristics of Pb...iosrjce
IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of mechanical and civil engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in mechanical and civil engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Comparison of Fatigue Characteristic for AISI 1039 Steel with Surface Treatmentijceronline
Wear and fatigue resistance in steel components used in various industries can be improved by surface treatments. Coatings systems which are used for improving the mechanical properties, generally, decreased the components fatigue life due to micro cracks, that propagate through the substrate , it is possible to improve the fatigue resistance of a component by the application of shot peening treatment, whose compressive residual stresses delay or eliminate the initiation and propagation of fatigue cracks. The aim of this study is to obtain the fatigue limit of untreated, shot peened, and hard chromium coating of medium carbon steel AISI 1039 and comparison between them. Fatigue tests were carried out using small samples with 4 mm diameter, with hard chromium layer of (47.1) µm thick. Rotating-bending fatigue test was carried out on samples after shot peening with steel balls of about 20 minutes peening time. Experimental results showed that hard chromium electroplating decreased the fatigue life and fatigue limit in comparison with the uncoated steel. As the highest thickness for coating was 23µm. On the other hand, Shot peening Results indicated that the fatigue strengths of samples are increased and the highest fatigue limit was (298.566Mpa) after treated the samples by shot peening for 20 minutes.
Effect of PVD Coating and Carburizing on Wear Characteristics of Low Carbon S...IJERD Editor
Wear is a relative cyclic motion with small amplitude which occurs between two oscillating
surfaces, depending upon the loading conditions, material properties and environment. Surface Engineering
such as surface treatment, coating and surface modifications are employed to minimise the friction and improve
wear resistance of steel. In this work the low carbon steel substrate is coated with Al2O3 by using physical
vapour deposition process and the other sampling material is heat treated by carburizing process. In the present
study, the wear resistance of heat treated and coated steels were evaluated through the pin-on-disk using
variable loads and wear is measured by the wear track width and wear graphs are shown for coated material and
heat treated material. Finally, the comparison is concluded by observing the variations in wear characteristics
between the two samples. Furthermore morphological study of wear is made for in-depth analysis
HVOF Sprayed WC-Cocr Coating on Mild Steel: Microstructure and Wear Evaluationiosrjce
IOSR Journal of Applied Physics (IOSR-JAP) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of physics and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in applied physics. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
The document describes an experiment to determine how corrosion affects the geometric characteristics and theoretical ultimate load-capacity of steel samples. Steel samples were subjected to accelerated electrochemical corrosion in cycles and measured after each cycle. The corrosion caused a non-linear decrease in diameter along the sample length. Theoretical calculations using these geometric data showed that while corrosion caused a slight decrease, it significantly reduced the ultimate load-capacity. The results provide insight into how corrosion progressively impacts steel strength over time.
IRJET- Experimental Investigation on Concrete by Partial Replacement of Coars...IRJET Journal
This document presents the results of an experimental study investigating the effects of partially replacing coarse aggregate with cinder in concrete. M30 concrete mixes were designed using the ISI method. Cubes and cylinders were cast with 0%, 20%, 40%, 60%, 80%, and 100% replacement of coarse aggregate with cinder and tested for compressive strength, split tensile strength, and flexural strength at 7 and 28 days. The results showed that compressive strength, split tensile strength, and flexural strength generally decreased as the cinder replacement ratio increased. The highest strengths were obtained with 40-60% cinder replacement. Overall, partially replacing coarse aggregate with cinder produced lightweight concrete with reasonably good strength.
The document investigates the effect of deep cryogenic treatment (DCT) on the microstructure and properties of an AE42 magnesium alloy. Key findings include:
1) DCT for 4-16 hours reduced the volume fraction of the brittle Al4RE phase in the alloy microstructure. The longest DCT time of 16 hours produced the lowest Al4RE content.
2) UTS and ductility increased with DCT, attributed to dissolution of the brittle Al4RE phase, while YS saw a marginal rise. The 16-hour DCT alloy achieved the best tensile properties.
3) Creep resistance decreased with DCT due to reduced amounts of the thermally stable Al
MICROSTRUCTURAL CHARACTERIZATION AND HOT EROSION BEHAVIOR OF CRC-NICR COATED ...IAEME Publication
Erosion behavior of the High Velocity Oxygen Fuel (HVOF) deposited CrC - NiCr coating on stainless steel was evaluated. Th e solid particle erosion stu dy was conducted using an air jet erosion test rig at a velocity 60m/sec and impingement angle 60 ° , 75 ° and 90 ° , on HVOF spray coated steel at 600 ° C. Microstructure, chemical composition, phases present in the coating on the steel substrate was studied by using Scanning Electron Microscope (SEM) and X - Ray Diffraction method. The Hardness is gradually increasing with increasing content of Cr 3 C 2 particles in all three samples. The erosion mechanism of coatings was also discussed and erosion rate is maximum at impingement angle 75 °
The document discusses concrete durability strategies for the Rion-Antirion Bridge project in Greece, which requires concrete structures to withstand corrosion for 120 years in a marine environment. To achieve this, high-quality concrete was used with specifications exceeding contractual requirements. Testing showed the concrete had low chloride ion permeability and diffusion coefficients, validating its ability to prevent corrosion over 120 years. Strategies included using slag cement, low water-to-cement ratios, and increased concrete covers in more exposed zones to protect reinforcing steel from chlorides.
Destructive and Non- Destructive Testing for Concrete in Sudan - A Comparativ...iosrjce
IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of mechanical and civil engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in mechanical and civil engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
This document summarizes a study on the effects of yttrium on the mechanical properties and chemical stability of the passive film on an aluminide coating applied to 1045 steel. Samples were prepared with and without the addition of yttrium. Nanoindentation tests found that the yttrium-containing coating had greater hardness and elasticity than the yttrium-free coating. Scratch tests also showed that the passive film on the yttrium coating had a higher critical load, indicating greater resistance to failure. Electron work function measurements demonstrated that the passive film on the yttrium coating was more chemically stable. The addition of yttrium improved both the mechanical properties and chemical stability of the passive film, enhancing corrosion and
A Review on Mechanical and Wear Properties of Heat Treated SteelIJSRD
This Review Paper describes effects of heat treatment on various material by varying process parameters and by using different types of heat treatment process. The heat treatment includes heating & cooling operations or the sequence of two or more such operations applied to any material in order to modify metallurgical structure and alter its physical, mechanical and chemical properties. This Review paper shows progress and research in the field of heat treatment process. Different types of heat treatment processes such as annealing, normalising, nitriding, hardening, tempering carburising used & available in recent time. This paper deals with important progress work on heat treatment and its process parameters.
Non Destructive Testing of Concrete CubesAvishek Ghosh
This document summarizes a presentation on non-destructive testing of concrete cubes under varied curing conditions. The presentation discusses rebound hammer testing and ultrasonic pulse velocity testing conducted on concrete cubes cured under four different curing regimes to determine compressive strength and detect voids. Key findings include the 14 days curing regime achieved the target compressive strength, placement of transducers impacts void detection by ultrasonic pulse velocity, and rebound hammer strengths were slightly lower than compressive strengths. The presentation concludes with references for further information.
Effect of Nano-Tio2addition on Mechanical Properties of Concrete and Corrosio...IJERA Editor
Concrete science is a multidisciplinary area of research where nanotechnology potentially offers the opportunity to enhance the understanding of concrete behavior, to engineer its properties and to lower production and ecological cost of construction materials. The main objective of this research was to evaluate the effect of nanoTiO2on compressive strength,bond strength and corrosion behavior of reinforcement bars. It has been found that the compressive strength, bond strength and corrosion resistance was increased with increasing nano-TiO2to 1.5wt. % as replacement of cement. Beyond this value, these properties decrease.
The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology
Corrosion Inhibition of Carbon Steel In Sulfuric Acid by Sodium CaprylateIJERA Editor
The interaction of a sodium salt of octanoic acid, sodium caprylate (SC), with a carbon steel (CS) surface was
investigated, using range of experimental techniques. It was shown that SC acts as a good CS general corrosion
inhibitor, yielding a maximum corrosion inhibition efficiency of 77%. This high inhibition efficiency is
maintained even at higher temperatures. It was determined that SC inhibits both partial corrosion reactions, and
can thus be considered to be a mixed-type inhibitor. The adsorption of SC on the CS surface was described by
the Langmuir adsorption isotherm. It was found that this process is spontaneous, irreversible and driven by the
entropy gain. The CS surface morphology was studied by SEM and it was demonstrated that SC is a very
effective general corrosion inhibitor of CS. This also was confirmed by contact angle measurements which
showed that the CS surface became more hydrophobic when the SC was added to the solution.
Corrosion Inhibition of Carbon Steel In Sulfuric Acid by Sodium CaprylateIJERA Editor
The interaction of a sodium salt of octanoic acid, sodium caprylate (SC), with a carbon steel (CS) surface was
investigated, using range of experimental techniques. It was shown that SC acts as a good CS general corrosion
inhibitor, yielding a maximum corrosion inhibition efficiency of 77%. This high inhibition efficiency is
maintained even at higher temperatures. It was determined that SC inhibits both partial corrosion reactions, and
can thus be considered to be a mixed-type inhibitor. The adsorption of SC on the CS surface was described by
the Langmuir adsorption isotherm. It was found that this process is spontaneous, irreversible and driven by the
entropy gain. The CS surface morphology was studied by SEM and it was demonstrated that SC is a very
effective general corrosion inhibitor of CS. This also was confirmed by contact angle measurements which
showed that the CS surface became more hydrophobic when the SC was added to the solution.
Review on Erosion and Corrosion Studies on Steel WeldmentsIRJET Journal
This document provides an extensive literature review on erosion and corrosion studies carried out on various grades of steel weldments. It discusses different types of erosion and corrosion, parameters that affect erosion rates like particle size and impact angle. Methods to analyze erosion and corrosion rates like weight loss tests and SEM imaging are also summarized. The review focuses on erosion and corrosion behavior of carbon steels like A106 grade steel typically used in pipes under various environmental conditions like chemicals and high temperatures.
An equiaxed, submicron grain size distribution was generated in an Al (0.1 wt.% Sc) alloy by
processing through equal channel angular pressing followed by a low temperature pre-
ageing heat treatment. The alloy was subsequently annealed for various times at 300, 350,
400 and 450° C for investigating the thermal stability of the deformation microstructure. It
was found that up to 400° C, the submicron grain structure coarsens slowly and uniformly by
a process of continuous recrystallization.
Influence of phase transformation on the work hardening characteristics of Pb...iosrjce
IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of mechanical and civil engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in mechanical and civil engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Comparison of Fatigue Characteristic for AISI 1039 Steel with Surface Treatmentijceronline
Wear and fatigue resistance in steel components used in various industries can be improved by surface treatments. Coatings systems which are used for improving the mechanical properties, generally, decreased the components fatigue life due to micro cracks, that propagate through the substrate , it is possible to improve the fatigue resistance of a component by the application of shot peening treatment, whose compressive residual stresses delay or eliminate the initiation and propagation of fatigue cracks. The aim of this study is to obtain the fatigue limit of untreated, shot peened, and hard chromium coating of medium carbon steel AISI 1039 and comparison between them. Fatigue tests were carried out using small samples with 4 mm diameter, with hard chromium layer of (47.1) µm thick. Rotating-bending fatigue test was carried out on samples after shot peening with steel balls of about 20 minutes peening time. Experimental results showed that hard chromium electroplating decreased the fatigue life and fatigue limit in comparison with the uncoated steel. As the highest thickness for coating was 23µm. On the other hand, Shot peening Results indicated that the fatigue strengths of samples are increased and the highest fatigue limit was (298.566Mpa) after treated the samples by shot peening for 20 minutes.
Effect of PVD Coating and Carburizing on Wear Characteristics of Low Carbon S...IJERD Editor
Wear is a relative cyclic motion with small amplitude which occurs between two oscillating
surfaces, depending upon the loading conditions, material properties and environment. Surface Engineering
such as surface treatment, coating and surface modifications are employed to minimise the friction and improve
wear resistance of steel. In this work the low carbon steel substrate is coated with Al2O3 by using physical
vapour deposition process and the other sampling material is heat treated by carburizing process. In the present
study, the wear resistance of heat treated and coated steels were evaluated through the pin-on-disk using
variable loads and wear is measured by the wear track width and wear graphs are shown for coated material and
heat treated material. Finally, the comparison is concluded by observing the variations in wear characteristics
between the two samples. Furthermore morphological study of wear is made for in-depth analysis
HVOF Sprayed WC-Cocr Coating on Mild Steel: Microstructure and Wear Evaluationiosrjce
IOSR Journal of Applied Physics (IOSR-JAP) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of physics and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in applied physics. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
The document describes an experiment to determine how corrosion affects the geometric characteristics and theoretical ultimate load-capacity of steel samples. Steel samples were subjected to accelerated electrochemical corrosion in cycles and measured after each cycle. The corrosion caused a non-linear decrease in diameter along the sample length. Theoretical calculations using these geometric data showed that while corrosion caused a slight decrease, it significantly reduced the ultimate load-capacity. The results provide insight into how corrosion progressively impacts steel strength over time.
IRJET- Experimental Investigation on Concrete by Partial Replacement of Coars...IRJET Journal
This document presents the results of an experimental study investigating the effects of partially replacing coarse aggregate with cinder in concrete. M30 concrete mixes were designed using the ISI method. Cubes and cylinders were cast with 0%, 20%, 40%, 60%, 80%, and 100% replacement of coarse aggregate with cinder and tested for compressive strength, split tensile strength, and flexural strength at 7 and 28 days. The results showed that compressive strength, split tensile strength, and flexural strength generally decreased as the cinder replacement ratio increased. The highest strengths were obtained with 40-60% cinder replacement. Overall, partially replacing coarse aggregate with cinder produced lightweight concrete with reasonably good strength.
The document investigates the effect of deep cryogenic treatment (DCT) on the microstructure and properties of an AE42 magnesium alloy. Key findings include:
1) DCT for 4-16 hours reduced the volume fraction of the brittle Al4RE phase in the alloy microstructure. The longest DCT time of 16 hours produced the lowest Al4RE content.
2) UTS and ductility increased with DCT, attributed to dissolution of the brittle Al4RE phase, while YS saw a marginal rise. The 16-hour DCT alloy achieved the best tensile properties.
3) Creep resistance decreased with DCT due to reduced amounts of the thermally stable Al
MICROSTRUCTURAL CHARACTERIZATION AND HOT EROSION BEHAVIOR OF CRC-NICR COATED ...IAEME Publication
Erosion behavior of the High Velocity Oxygen Fuel (HVOF) deposited CrC - NiCr coating on stainless steel was evaluated. Th e solid particle erosion stu dy was conducted using an air jet erosion test rig at a velocity 60m/sec and impingement angle 60 ° , 75 ° and 90 ° , on HVOF spray coated steel at 600 ° C. Microstructure, chemical composition, phases present in the coating on the steel substrate was studied by using Scanning Electron Microscope (SEM) and X - Ray Diffraction method. The Hardness is gradually increasing with increasing content of Cr 3 C 2 particles in all three samples. The erosion mechanism of coatings was also discussed and erosion rate is maximum at impingement angle 75 °
The document discusses concrete durability strategies for the Rion-Antirion Bridge project in Greece, which requires concrete structures to withstand corrosion for 120 years in a marine environment. To achieve this, high-quality concrete was used with specifications exceeding contractual requirements. Testing showed the concrete had low chloride ion permeability and diffusion coefficients, validating its ability to prevent corrosion over 120 years. Strategies included using slag cement, low water-to-cement ratios, and increased concrete covers in more exposed zones to protect reinforcing steel from chlorides.
Destructive and Non- Destructive Testing for Concrete in Sudan - A Comparativ...iosrjce
IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of mechanical and civil engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in mechanical and civil engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
This document summarizes a study on the effects of yttrium on the mechanical properties and chemical stability of the passive film on an aluminide coating applied to 1045 steel. Samples were prepared with and without the addition of yttrium. Nanoindentation tests found that the yttrium-containing coating had greater hardness and elasticity than the yttrium-free coating. Scratch tests also showed that the passive film on the yttrium coating had a higher critical load, indicating greater resistance to failure. Electron work function measurements demonstrated that the passive film on the yttrium coating was more chemically stable. The addition of yttrium improved both the mechanical properties and chemical stability of the passive film, enhancing corrosion and
A Review on Mechanical and Wear Properties of Heat Treated SteelIJSRD
This Review Paper describes effects of heat treatment on various material by varying process parameters and by using different types of heat treatment process. The heat treatment includes heating & cooling operations or the sequence of two or more such operations applied to any material in order to modify metallurgical structure and alter its physical, mechanical and chemical properties. This Review paper shows progress and research in the field of heat treatment process. Different types of heat treatment processes such as annealing, normalising, nitriding, hardening, tempering carburising used & available in recent time. This paper deals with important progress work on heat treatment and its process parameters.
Non Destructive Testing of Concrete CubesAvishek Ghosh
This document summarizes a presentation on non-destructive testing of concrete cubes under varied curing conditions. The presentation discusses rebound hammer testing and ultrasonic pulse velocity testing conducted on concrete cubes cured under four different curing regimes to determine compressive strength and detect voids. Key findings include the 14 days curing regime achieved the target compressive strength, placement of transducers impacts void detection by ultrasonic pulse velocity, and rebound hammer strengths were slightly lower than compressive strengths. The presentation concludes with references for further information.
Effect of Nano-Tio2addition on Mechanical Properties of Concrete and Corrosio...IJERA Editor
Concrete science is a multidisciplinary area of research where nanotechnology potentially offers the opportunity to enhance the understanding of concrete behavior, to engineer its properties and to lower production and ecological cost of construction materials. The main objective of this research was to evaluate the effect of nanoTiO2on compressive strength,bond strength and corrosion behavior of reinforcement bars. It has been found that the compressive strength, bond strength and corrosion resistance was increased with increasing nano-TiO2to 1.5wt. % as replacement of cement. Beyond this value, these properties decrease.
The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology
Corrosion Inhibition of Carbon Steel In Sulfuric Acid by Sodium CaprylateIJERA Editor
The interaction of a sodium salt of octanoic acid, sodium caprylate (SC), with a carbon steel (CS) surface was
investigated, using range of experimental techniques. It was shown that SC acts as a good CS general corrosion
inhibitor, yielding a maximum corrosion inhibition efficiency of 77%. This high inhibition efficiency is
maintained even at higher temperatures. It was determined that SC inhibits both partial corrosion reactions, and
can thus be considered to be a mixed-type inhibitor. The adsorption of SC on the CS surface was described by
the Langmuir adsorption isotherm. It was found that this process is spontaneous, irreversible and driven by the
entropy gain. The CS surface morphology was studied by SEM and it was demonstrated that SC is a very
effective general corrosion inhibitor of CS. This also was confirmed by contact angle measurements which
showed that the CS surface became more hydrophobic when the SC was added to the solution.
Corrosion Inhibition of Carbon Steel In Sulfuric Acid by Sodium CaprylateIJERA Editor
The interaction of a sodium salt of octanoic acid, sodium caprylate (SC), with a carbon steel (CS) surface was
investigated, using range of experimental techniques. It was shown that SC acts as a good CS general corrosion
inhibitor, yielding a maximum corrosion inhibition efficiency of 77%. This high inhibition efficiency is
maintained even at higher temperatures. It was determined that SC inhibits both partial corrosion reactions, and
can thus be considered to be a mixed-type inhibitor. The adsorption of SC on the CS surface was described by
the Langmuir adsorption isotherm. It was found that this process is spontaneous, irreversible and driven by the
entropy gain. The CS surface morphology was studied by SEM and it was demonstrated that SC is a very
effective general corrosion inhibitor of CS. This also was confirmed by contact angle measurements which
showed that the CS surface became more hydrophobic when the SC was added to the solution.
Correlation between the Interface Width and the Adhesion Strength of Copper F...IOSRJAP
1) The document examines how applying a negative bias voltage to carbon steel substrates during copper film deposition via magnetron sputtering affects the adhesion strength and interface width between the film and substrate.
2) Adhesion strength, measured via scratch testing, increased with higher bias voltage. The critical load reached 18.5g at -600V bias compared to 9.5g for an unbiased substrate.
3) Interface width, measured by Auger electron spectroscopy, also increased with higher bias voltage. The width was 335nm at -600V bias versus 180nm for an unbiased substrate.
4) The results suggest that bias voltage promotes diffusion and mixing at the interface, widening it. This, along
Interface characterizations of diamond coated tools by scratch testing and si...The University of Alabama
1. Micro-scratch tests were conducted on diamond-coated tungsten-carbide substrates to investigate coating adhesion. Acoustic emission signals and fluctuations in tangential force indicated when coating delamination occurred, around a critical normal load of 4-6 Newtons.
2. A finite element model with a cohesive interface was developed to simulate the scratch process and evaluate interface properties based on the experimental critical load. Adjusting the cohesive properties approximated the measured critical load.
3. Scratch simulations showed high compressive and tensile stresses developed in the coating near the slider at delamination onset, around 4 Newtons normal load, consistent with experimental observations. The model can be used to evaluate adhesion of different diamond
Behavior of carbon steel in simulated concrete pore solutions of air-entraine...Adriana de Araujo
In Brazil, the air-entrained concrete has been extensively used as structural walls of housing units. Some of these units built recently in urban areas were inspected. Upon inspection, a significant variation of the potential corrosion measurement was obtained and reddish stains on the surface of the reinforcement were also observed, indicating active state of corrosion. Not always the concrete was fully carbonated and a chloride contamination was not detected. The occurrence of crevice corrosion was pointed as a possible cause of the premature corrosion as a non-uniform contact of the concrete with the reinforcement surface was detected.
In order to better understand the occurrence of premature corrosion of the inspected reinforcement, a complementary study was conducted at the laboratory to characterize air-entrained concretes and evaluate the behavior of steel bars immersed in solutions that simulate the water in the pores of these concrete and compare them to the pore solution of an ordinary Portland concrete.
The steel bars were evaluated under three conditions: blasted, corroded and galvanized. An intentional crevice was introduced on one of the bars. The behavior of the bars was monitored by visual examination and by electrochemical measurements. Finally, the corrosion rate was calculated. Tests on concrete specimens were also conducted to validate the results.
The characterization tests showed an inferior quality of the air-entrained concretes, having both high concentrations of pores, many of them fully interconnected. This justified the high deep carbonation observed in a short period of time and a variable electrical resistivity detected in the field.
The pore-solution immersion tests showed the higher corrosion susceptibility of metallic reinforcement in air-entrained concretes especially at the crevice areas. In the studied air-entrained concretes, the corrosion occurred preferentially under the sealant applied on the bar extremities. In one of them, corrosion was also observed on the free surface of the blasted bars. The corrosion was also observed in the air-entrained concrete specimens, confirming the tests solution results.
Analyzing Adhesion of Epoxy/Steel Interlayer in Scratch TestIJERA Editor
The document summarizes a study that investigated how different parameters affect the adhesion strength of epoxy adhesives bonded to zinc-plated mild steel. Scratch tests were performed using two epoxy adhesives and zinc-plated mild steel adherends treated with different surface treatments. A Taguchi experimental design was used to test combinations of surface treatment, adhesive type, blade angle, and adhesive thickness. Results found that surface treatment and thickness were the most influential parameters, affecting scratch force by 52.4% and 19.9% respectively, and scratch energy by 44.0% and 25.6% respectively.
Investigation on the behaviour of alfa composite in pre and post heat treated...eSAT Journals
Abstract
Of the many types of particulate reinforcements fly ash is one type that is being used from the recent past to develop the composites. In the current research fly ash is reinforced in the aluminium alloy AA2024 to develop ALFA (ALuminium Fly Ash) composites. The stir casting technique is employed in the development of the said composite as this technique is economical and would produce a composite with fairly uniform distribution of the fly ash reinforcement in the alloy matrix. The fly ash was added in 2.5 and 5% by weight to the molten metal. Increase in the percentage weight of fly ash reinforcement resulted improvement in the mechanical properties. The composite is tested for hardness, tensile strength and wear performance under pre-heat treatment, as quenched and in peak hardened conditions. The peak hardened composite showed a superior hardness, tensile strength and wear resistance than the others.
Keywords: stir casting, fly ash composites, heat treatment, and characterization
Erosive Corrosive Wear Performance of Single Layer CrN Coatings on AISI 304 S...IJAEMSJORNAL
The purpose of present study was to investigate the erosive corrosive wear behavior of single layer (CrN) coatings on AISI 304 Stainless Steel samples with varying coating thickness (0-200 nm) in the range of 50 nm. The slurry jet erosive test was conducted on Slurry Jet Erosion Tester in saline slurry (3.5wt% salt) under the different working conditions with varying impact velocity (10-25 m/s), impingement angle (30°-75°) and erodent discharge (160-280 gm/min). Steady state analysis was applied to find optimum parameters for the minimization of erosion rate of various coated and uncoated samples. The finding of steady state condition tests indicated that the erosion rate increased with the increase in impact velocity and erodent discharge but decreased with the increase in coating thickness. The results also indicated that erodent discharge was the most significant factor, followed by impingement angle and impact velocity for the CrN coated samples. The SEM characterization of the eroded samples was carried out in order to analyze the topography of the eroded surface to investigate the wear mechanisms induced by slurry jet erosion test.
Effect of dilution on microstructure and hardness of a nickel-base hardfacing...RAMASUBBU VELAYUTHAM
1) The document examines the effect of dilution on the microstructure and hardness of a nickel-base hardfacing alloy deposited on an austenitic stainless steel substrate.
2) Electron probe microanalysis revealed considerable dilution of the hardfacing alloy by the substrate material within the first 2.5mm of the deposit, altering the chemistry, microstructure, and decreasing the hardness in this region.
3) Beyond 2.5mm from the interface, the hardness increases to levels comparable to the undiluted alloy as subsequent deposit layers approach, due to decreasing dilution effects farther from the substrate.
The document summarizes a study that investigated the spark plasma sinterability and dry sliding wear resistance of tungsten carbide (WC) densified with cobalt (Co), cobalt-nickel (Co+Ni), and cobalt-nickel-chromium (Co+Ni+Cr) binders. Dilatometric spark plasma sintering tests showed that partial substitutions of Co with Ni or Ni+Cr decreased sinterability, with Ni+Cr having a greater negative effect. However, isothermal sintering under pressure was affected little by the substitutions. Testing found the materials were very resistant to dry sliding wear, with WC-Co+Ni+Cr exhibiting the greatest hardness and wear resistance due to its higher
1) The document investigates the effect of cation and anion sizes on the charge storage capabilities of graphite nanosheets as electrode materials for electrochemical double layer capacitors.
2) Scanning electron microscope images confirm the layered structure of the graphite nanosheets used, which are 12nm thick with 3.36 Angstrom spacing between layers.
3) Electrochemical measurements using cyclic voltammetry and impedance spectroscopy indicate that the graphite electrodes exhibited better charge storage and delivery in 3M NaCl electrolyte compared to NaOH and KOH electrolytes, due to the smaller ion sizes matching better with the graphite structure.
This document discusses research on improving the rolling contact fatigue wear resistance of train track alloy steel through laser processing of biomimetic coupling units on the steel surface. Key points:
1) Biomimetic units with different striation angles (30°, 45°, 60°) were created on alloy steel samples using laser remelting to mimic structures found in nature.
2) Testing found the samples with units had significantly less mass loss than untreated samples when subjected to rolling contact fatigue wear testing, indicating better wear resistance.
3) Samples with 30° and 60° striation units performed best, with mass loss reductions of 85% and 86.3% respectively, compared to 73.9% for the 45
Erosion wear behaviour of plasma sprayed ni crsibEbe Nezer G
The document discusses several studies on erosion wear behavior and coatings:
1) One study examines the erosion wear behavior of a plasma sprayed NiCrSiB/Al2O3 composite coating on AISI 304 steel. Testing found the coating protects the substrate at 30° and 90° impact angles.
2) Another study evaluates the cavitation erosion and corrosion resistance of WC-CoCr and FeCrSiBMn coatings deposited by HVOF spraying. The WC-CoCr coating showed better resistance in NaCl solution.
3) A third study optimizes NiCrSiB/WC-Co coatings deposited by HVOF using Taguchi methods. Testing identified standoff distance and powder
Experimental Studies on the Prediction of Corrosion Levels in Reinforced TMT ...IRJET Journal
The document summarizes experimental studies on predicting corrosion levels in reinforced TMT bars in normal vibrated concrete (NVC) and self-consolidating concrete (SCC) exposed to a marine environment. Specimens of NVC and SCC with TMT bars embedded were immersed in de-ionized water with varying concentrations of NaCl and MgSO4 for curing periods of 28, 45, 60, and 90 days. Corrosion levels in the TMT bars after curing were then predicted by measuring potential differences between points on the specimens using a saturated calomel electrode and open circuit potential method. The studies aimed to investigate corrosion levels in TMT bars in NVC and SCC exposed to the marine environment
This document summarizes a study on the effect of chromium content on the microstructure and wear resistance of Fe-Cr-C hard facing layers. Hard facing layers containing various amounts of chromium were deposited on mild steel using shielded metal arc welding. Testing found that microstructure consisted of primary (Cr, Fe)7C3 carbides and eutectic phases. Higher chromium content refined the carbides. Wear resistance testing found that higher chromium, carbon, and silicon content resulted in higher hardness and less wear. Electrode I, with higher amounts of these elements, exhibited less wear than Electrode II. In conclusion, chromium content significantly affects microstructure and wear resistance, with higher chromium improving hardness and wear performance of Fe
Creep is defined as the plastic deformation under sustain load. Creep strain depends
primarily on the duration of sustained loading. It has been widely acknowledged that creep of
concrete is greatly influenced by the surrounding ambient. Creep induces the deflection of the
structural member with time. Hence the study on creep of concrete is necessary to prevent failure. A
concrete cylinder is casted for two different grades and the load of 40% of its compressive strength
is applied constantly. Creep is measured with time. A time - dependent creep is provided in a graph
showing its variation.
A Review Study of Investigation on Titanium Alloy Coatings for Wear Resistanc...IRJET Journal
This document summarizes a review study investigating titanium alloy coatings deposited via physical vapor deposition (PVD) for improved wear resistance. PVD was identified as a cost-effective coating method that provides benefits like superior wear and corrosion resistance as well as low friction. The coatings were deposited on mild steel substrates for pump shaft applications. Characterization techniques like X-ray diffraction and ball-on-disc testing were used to analyze the coatings. The literature review discussed various coating materials, deposition methods, and experimental factors related to evaluating PVD coatings for wear resistance.
Amorphous-nano-crystalline silicon composite thin films (a-nc-Si:H) samples were synthesized by
Plasma Enhanced Chemical Vapor Deposition technique. The measurement of DC conductivities was
accomplished using Dielectric spectroscopy (Impedance Spectroscopy) in wide frequency and temperature range.
In analysis of impedance data, two approaches were tested: the Debye type equivalent circuit with two parallel R
and CPEs (constant phase elements) and modified one, with tree parallel R and CPEs including crystal grain
boundary effects. It was found that the later better fits to experimental results properly describes crystal grains
dielectric effect and hydrogen concentration indicating presence of strain. The amorphous matrix showed larger
resistance and lower capacity than nano-crystal phase. Also it was found that composite silicon thin film cannot
be properly described by equivalent circuit only with resistors and constant phase elements in serial relation
Presentation of IEEE Slovenia CIS (Computational Intelligence Society) Chapte...University of Maribor
Slides from talk presenting:
Aleš Zamuda: Presentation of IEEE Slovenia CIS (Computational Intelligence Society) Chapter and Networking.
Presentation at IcETRAN 2024 session:
"Inter-Society Networking Panel GRSS/MTT-S/CIS
Panel Session: Promoting Connection and Cooperation"
IEEE Slovenia GRSS
IEEE Serbia and Montenegro MTT-S
IEEE Slovenia CIS
11TH INTERNATIONAL CONFERENCE ON ELECTRICAL, ELECTRONIC AND COMPUTING ENGINEERING
3-6 June 2024, Niš, Serbia
Introduction- e - waste – definition - sources of e-waste– hazardous substances in e-waste - effects of e-waste on environment and human health- need for e-waste management– e-waste handling rules - waste minimization techniques for managing e-waste – recycling of e-waste - disposal treatment methods of e- waste – mechanism of extraction of precious metal from leaching solution-global Scenario of E-waste – E-waste in India- case studies.
Optimizing Gradle Builds - Gradle DPE Tour Berlin 2024Sinan KOZAK
Sinan from the Delivery Hero mobile infrastructure engineering team shares a deep dive into performance acceleration with Gradle build cache optimizations. Sinan shares their journey into solving complex build-cache problems that affect Gradle builds. By understanding the challenges and solutions found in our journey, we aim to demonstrate the possibilities for faster builds. The case study reveals how overlapping outputs and cache misconfigurations led to significant increases in build times, especially as the project scaled up with numerous modules using Paparazzi tests. The journey from diagnosing to defeating cache issues offers invaluable lessons on maintaining cache integrity without sacrificing functionality.
Embedded machine learning-based road conditions and driving behavior monitoringIJECEIAES
Car accident rates have increased in recent years, resulting in losses in human lives, properties, and other financial costs. An embedded machine learning-based system is developed to address this critical issue. The system can monitor road conditions, detect driving patterns, and identify aggressive driving behaviors. The system is based on neural networks trained on a comprehensive dataset of driving events, driving styles, and road conditions. The system effectively detects potential risks and helps mitigate the frequency and impact of accidents. The primary goal is to ensure the safety of drivers and vehicles. Collecting data involved gathering information on three key road events: normal street and normal drive, speed bumps, circular yellow speed bumps, and three aggressive driving actions: sudden start, sudden stop, and sudden entry. The gathered data is processed and analyzed using a machine learning system designed for limited power and memory devices. The developed system resulted in 91.9% accuracy, 93.6% precision, and 92% recall. The achieved inference time on an Arduino Nano 33 BLE Sense with a 32-bit CPU running at 64 MHz is 34 ms and requires 2.6 kB peak RAM and 139.9 kB program flash memory, making it suitable for resource-constrained embedded systems.
Literature Review Basics and Understanding Reference Management.pptxDr Ramhari Poudyal
Three-day training on academic research focuses on analytical tools at United Technical College, supported by the University Grant Commission, Nepal. 24-26 May 2024
A SYSTEMATIC RISK ASSESSMENT APPROACH FOR SECURING THE SMART IRRIGATION SYSTEMSIJNSA Journal
The smart irrigation system represents an innovative approach to optimize water usage in agricultural and landscaping practices. The integration of cutting-edge technologies, including sensors, actuators, and data analysis, empowers this system to provide accurate monitoring and control of irrigation processes by leveraging real-time environmental conditions. The main objective of a smart irrigation system is to optimize water efficiency, minimize expenses, and foster the adoption of sustainable water management methods. This paper conducts a systematic risk assessment by exploring the key components/assets and their functionalities in the smart irrigation system. The crucial role of sensors in gathering data on soil moisture, weather patterns, and plant well-being is emphasized in this system. These sensors enable intelligent decision-making in irrigation scheduling and water distribution, leading to enhanced water efficiency and sustainable water management practices. Actuators enable automated control of irrigation devices, ensuring precise and targeted water delivery to plants. Additionally, the paper addresses the potential threat and vulnerabilities associated with smart irrigation systems. It discusses limitations of the system, such as power constraints and computational capabilities, and calculates the potential security risks. The paper suggests possible risk treatment methods for effective secure system operation. In conclusion, the paper emphasizes the significant benefits of implementing smart irrigation systems, including improved water conservation, increased crop yield, and reduced environmental impact. Additionally, based on the security analysis conducted, the paper recommends the implementation of countermeasures and security approaches to address vulnerabilities and ensure the integrity and reliability of the system. By incorporating these measures, smart irrigation technology can revolutionize water management practices in agriculture, promoting sustainability, resource efficiency, and safeguarding against potential security threats.
KuberTENes Birthday Bash Guadalajara - K8sGPT first impressionsVictor Morales
K8sGPT is a tool that analyzes and diagnoses Kubernetes clusters. This presentation was used to share the requirements and dependencies to deploy K8sGPT in a local environment.
CHINA’S GEO-ECONOMIC OUTREACH IN CENTRAL ASIAN COUNTRIES AND FUTURE PROSPECTjpsjournal1
The rivalry between prominent international actors for dominance over Central Asia's hydrocarbon
reserves and the ancient silk trade route, along with China's diplomatic endeavours in the area, has been
referred to as the "New Great Game." This research centres on the power struggle, considering
geopolitical, geostrategic, and geoeconomic variables. Topics including trade, political hegemony, oil
politics, and conventional and nontraditional security are all explored and explained by the researcher.
Using Mackinder's Heartland, Spykman Rimland, and Hegemonic Stability theories, examines China's role
in Central Asia. This study adheres to the empirical epistemological method and has taken care of
objectivity. This study analyze primary and secondary research documents critically to elaborate role of
china’s geo economic outreach in central Asian countries and its future prospect. China is thriving in trade,
pipeline politics, and winning states, according to this study, thanks to important instruments like the
Shanghai Cooperation Organisation and the Belt and Road Economic Initiative. According to this study,
China is seeing significant success in commerce, pipeline politics, and gaining influence on other
governments. This success may be attributed to the effective utilisation of key tools such as the Shanghai
Cooperation Organisation and the Belt and Road Economic Initiative.
2. V.A. de Souza, A. Neville / Wear 255 (2003) 146–156 147
Table 1
Different coating compositions used in the work by Wentzel and Allen
[15]
Grade Binder Composition (wt.%)
WC Ni Cr Co
C6 Co 94 0 0 6
V6 Ni 94 6 0 0
V7 Ni–Cr 94 5.4 0.6 0
P6 Ni–Cr–Co 94 3.0 0.6 2.4
With the increased use of cermet coatings and solid cer-
mets in applications where corrosion can play a part in the
degradation process, it is becoming increasingly important
to be able to assess the effects of the joint erosion and cor-
rosion processes. Work in this area has therefore increased
since the start of the 1990s. Wentzel and Allen [15] inves-
tigated the behaviour of tungsten carbide hard metals with
different binders subjected to erosion–corrosion (using a
slurry of silica and water with 7 mass% of solids at 6.5 m/s)
using gravimetric and potentiodynamic techniques. In this
work four compositions were used in order to evaluate the
binder influence on the material performance (Table 1). It
was concluded that no simple relationship exists between
the erosion–corrosion performance and any one material
property. The slurry erosion resistance was improved by
alloying of the single component Co and Ni matrices. No
improvement in erosion–corrosion resistance was reported
by increasing the passivation of the binder.
Toma et al. [16] in a recent study of six thermal spray coat-
ings found that addition of Cr to a Co matrix in WC–Co cer-
mets increased resistance to erosion–corrosion. Work by the
authors [17–19] on the pure corrosion resistance of WC–Co
and WC–Co–Cr coatings also showed that the Cr changed
the principal mechanism of corrosion. Toma et al. also re-
ported that replacing some of the WC with another hard
phase particle (Cr3C2) can add resistance to the material in
terms of erosion performance. To optimise corrosion perfor-
mance the study concluded that a move from CoCr to NiCr
binders was effective.
In this paper the electrochemical behaviour of WC–Co–Cr
thermal sprayed coating is reported in severe impingement
conditions. The effect of the impinging jet on the corrosion
response is discussed. Through application of cathodic pro-
tection (CP) the effects of erosion, corrosion and interac-
tions between erosion and corrosion can be determined. In
the paper the relative importance of corrosion and erosion
effects in the material loss are discussed.
2. Experimental methods
The coating studied in this work is a Super D-Gun thermal
sprayed coating of the WC–Co–Cr generic type.
Characterisation of the coating microstructure was carried
out using light and scanning electron microscopy (SEM).
The environmental SEM is equipped with a LaB6 gun,
and is capable of operating as a conventional high-vacuum
SEM, or under low vacuum in ESEM mode. The ESEM
is fully equipped with a range of secondary electron (SE)
and back-scattered electron (BSE) detectors with an energy
dispersive X-ray (EDX) chemical analysis facility. Correc-
tions for atomic number, absorption and fluorescence (ZAF)
are achieved through a virtual standard calibration routine.
The crystalline phases of the coating were identified using
X-ray diffraction (XRD) and measurements were made
on a Siemens D500 diffractometer with copper radiation
K␣1+K␣2 and a scintillation counter (point detector), which
produces a θ versus 2θ scan (Bragg Brentano geometry).
The impingement apparatus comprised a liquid–solid jet
generated using a recirculating rig as shown in Fig. 1 and
described elsewhere [19]. The rig comprised a dual nozzle
system. The velocity of the jet for this study was kept con-
stant at 17 m/s. The solid loading in the 3.5% NaCl fluid
was varied at two levels of 200 and 500 mg/l. The sand size
distribution is given in Table 2. The temperature of the liq-
uid was 18 ◦C. For all tests the angle of impingement was
90◦. The surface area of the samples exposed to the jet was
3.8 cm2.
Electrochemical analysis was used in conjunction with
weight-loss analysis to determine the total material loss
(TWL) and to isolate the contributions due to pure corrosion
(C) and pure erosion (E). The corrosion rate was measured
in situ using a three-electrode electrochemical cell compris-
ing a Ag/AgCl reference electrode connected by means of a
salt bridge and a platinum counter electrode. DC anodic po-
larisation tests (in static conditions or under the impinging
jet) involved scanning the potential of the working electrode
(the specimen under examination) from the free corrosion
potential (Ecorr) in the more noble (positive) direction at a
fixed rate of 0.25 mV/s. The potential was scanned in the
positive direction until the current flowing in the external
circuit between the working and counter electrodes reached
a value of 500 A/cm2. The anodic polarisation tests were
started after 30 min exposure to static saline solution or the
impinging jet.
To measure changes in the corrosion rate as a func-
tion of solid loading on exposure period to the impinging
jet linear polarisation tests were conducted. In these tests
the potential of the working electrode (the sample under
erosion–corrosion) was shifted at a rate of 15 mV/min from
Table 2
Sand size distribution for the HST congleton silica sand used in
erosion–corrosion impingement tests
Sand size (mm) Percentage of total mass
<160 1
160 15
180 37
250 21
300 20
>425 7
3. 148 V.A. de Souza, A. Neville / Wear 255 (2003) 146–156
Fig. 1. (a) The rig configuration used in the experiments and (b) the electrochemical set up on the nozzle.
0.05 V negative to the free corrosion potential to 0.05 V
positive to the free corrosion potential. The applied poten-
tial is then a linear function of the current density in the
external cell and changes in the polarisation resistance (Rp)
can be calculated using the slope E/ I. In conjunction
with these measurements the free corrosion potential (Ecorr)
was also measured as a function of the solid loading.
In order to isolate the erosion component of material
loss, the weight loss was measured after exposure to the
impinging jet with applied CP which minimised the corro-
sion current on the sample. Calculations of the equilibrium
electrode potential for the Co/Co2+ reaction [20] confirmed
that application of −0.8 V (SCE) as the protection potential
was sufficiently near to the equilibrium electrode potential
to reduce corrosion effects to a negligible level. However,
the potential is not in the regime where hydrogen evolution
would be a potential complication at the cathode interface.
The CP was applied by potentiostatic means and involved
maintaining the potential of the working electrode at a con-
stant value of either −0.5 or −0.8 V against the saturated
calomel electrode (0.755 V Ag/AgCl).
Following all liquid–solid tests the surface was examined
using light and SEM to determine the extent of degradation
and to identify the material loss mechanisms.
3. Results
3.1. Coating characterisation
Fig. 2 shows an image of the coating microstructure where
the hard phase particles (light) are clear. The coating clearly
shows a lamellar structure produced by the layers built up
during the spraying process. The thickness of the coating is
250–300 m. The hard phase particles are typically 1–2 m
in size. The mean hardness of the coating is 1435 HV with
a standard deviation of 312 HV.
Table 3 shows the results of seven EDX measurements
taken over the surface of the coating. Each EDX measure-
ment was taken from a region of 500 m × 500 m. From
this it is clear that there is little spatial variation in the com-
position of the coating. The coating is nominally a WC–12%
Co–6% Cr. The oxygen content is approximately 1%.
The XRD trace for the coating is shown in Fig. 3. The
main constituents of the coating are identified. In compari-
son with WC–Co–Cr coatings sprayed using the HVOF pro-
cess, as reported in other work [17,18], it is evident that the
coating comprises a more complex microstructure. There is
evidence of decarburisation which has led to formation of
Fig. 2. Microstructure of the coating showing the hard phase particles
and the lamellar structure.
4. V.A. de Souza, A. Neville / Wear 255 (2003) 146–156 149
Table 3
EDX measurements on regions of 500 m×500 m on the coating surface
Element
(wt.%)
Sample number
1 2 3 4 5 6 7
C 2.5 2.6 3.1 3.5 3.7 3.5 3.5
O 0.9 0.8 1.0 0.1 0.7 1.1 0.9
Cr 5.8 5.7 5.6 5.9 6.0 5.8 5.9
Co 11.4 10.6 11.0 11.4 11.2 11.4 11.3
W 79.4 80.3 79.3 79.1 78.4 78.3 78.5
tungsten carbide forms other than simply the tungsten mono-
carbide species as well as phases. The amorphous phases
identified by the broad peaks in the 2θ range from 35◦ to
45◦ represent the dissolution of Co to form Co3W3O [7].
However, a residual amount of Co as metal is present which
was confirmed by XPS by Souza and Neville [21]. Also the
broad peaks could be accounted for by the (W, Cr)2C and
WC(1−x) phases.
3.2. Corrosion characteristics
3.2.1. Static conditions
The Ecorr of the coating in static 3.5% NaCl, measured
prior to starting the anodic polarisation curve, was consistent
at 285 ± 15 mV.
Fig. 4 shows the anodic polarisation curve for the
WC–CoCr coating in static 3.5% NaCl at 18 ◦C. For com-
parison the high grade superduplex stainless steel and the
UNS S31603 austenitic stainless steel anodic polarisation
curves under identical conditions are presented. It can be
seen that there are some similarities to the stainless steel
response and some contrasting features. The most important
contrasting feature is the rise in current at the potential near
to Ecorr on the coating compared with the extremely low
values of current (<1 A/cm2) exhibited by both stainless
Fig. 3. XRD trace from the as-received coating.
Fig. 4. Anodic polarisation curve measured on WC–Co–Cr coating in
static conditions compared with UNS S32760 (superduplex) and UNS
S31603 (austenitic) stainless steels.
steels. This is indicative of some corrosion activity existing
on the coating compared with the truly passive response of
both stainless steels. The breakdown potential exhibited on
UNS S32760 and UNS S31603 at 1 and 0.3 V, respectively,
is characteristic of passivity breakdown and represents the
potential at which localised corrosion is forced to occur. On
the coating it is clear that two such potentials are exhibited
at 0.55 and 0.93 V and these are related to localised corro-
sion at the carbide/binder interfaces and pitting of the CoCr
binder, respectively, as reported in another communication
[17]. From the anodic polarisation curve, it is possible to
determine a dissolution rate for the material through ex-
trapolation of the E–log I curve when plotted in the region
near to (from 50 mV to not more than 200 mV) Ecorr. This
5. 150 V.A. de Souza, A. Neville / Wear 255 (2003) 146–156
Fig. 5. Localised corrosion attack around the interface between the hard
phase particles and the matrix after anodic polarisation in static 3.5%
NaCl at 18 ◦C.
enables the corrosion current density to be determined and
for the coating in static conditions this is 1.3 A/cm2. Whilst
this is an extremely low value of corrosion current the im-
portant aspect to remember is that the coating comprises a
(W, Cr)2C and -WC(1−x) (which will have extremely low
electrochemical activity) and corrosion proceeds primarily
by dissolution of the Co phase in the first instance. This was
confirmed by ICP in [21]. The exposed area of the matrix is
much less than the ceramic phase (see Fig. 2) and, as such,
these corrosion currents (calculated from the total exposed
cermet surface) give underestimated dissolution rates (in
terms of thickness) for the metal phase. This is evident from
Fig. 5 where it is clear that severe localised dissolution of
the binder around the hard phase particle/matrix interface
has occurred. There are obvious implications for the role
of corrosion in erosion–corrosion when the integrity of the
bond can be lost through binder dissolution.
Measurement of the linear polarisation characteristics of
the WC–Co–Cr coating in static conditions produced the
E/ I value for Rp of 3500 . By assuming the values for
βa, βc of 0.1 V in Eq. (1) for calculation of the corrosion
Fig. 6. The free corrosion potential (Ecorr) as a function of solid loading under impingement conditions at 17 m/s and at normal impact angle. Solution
is 3.5% NaCl at 18 ◦C.
rate, the icorr value can be estimated. The resulting icorr value
is calculated
E
I
=
βaβc
2.3icorr(βa + βc)
= Rp (1)
to be 6.08 A which, for the specimen area of 3.8 cm2 is a
corrosion current density of 1.6 A/cm2. This value is very
close to the value determined by anodic polarisation in static
3.5% NaCl.
3.2.2. Corrosion characteristics under impingement free
corrosion potential
The free corrosion potential as a function of solid loading
is shown in Fig. 6. On subjecting the sample to impingement
(with no solids) there is a shift in the positive direction of
15 mV from the value recorded in static conditions. There
is then only a very small shift of <10 mV from the value at
zero solids (with impingement of liquid only) to the values
at 100 mg/l. This is in contrast to the response of stainless
steels under impingement as will be discussed later in the
paper. At between 100 and 200 mg/l there is the largest shift
in the active direction and beyond that solid loading only
very small active shifts are recorded.
3.2.3. Anodic polarisation
Fig. 7 shows the forward anodic polarisation curves for
the WC–Co–Cr coating in static conditions and under im-
pingement at 200 and 500 mg/l solids. As stated previously
in static conditions there are very low currents in the region
near to Ecorr and this is manifested in a very low icorr. Un-
der impingement at 200 mg/l the currents are larger over the
entire potential range. In the region near to Ecorr the cor-
rosion current densities can be determined and from Tafel
extrapolation the values in Table 4 are determined. This in-
dicates that there is a large effect of the impingement on
the corrosion current density—depolarisation of the anodic
dissolution reaction.
6. V.A. de Souza, A. Neville / Wear 255 (2003) 146–156 151
Fig. 7. Anodic polarisation curves under impingement conditions for the
WC–Co–Cr coating in 3.5% NaCl at 17 m/s at 18 ◦C.
Table 4
Corrosion current densities measured as a function of solid loading under
impingement
Condition Corrosion current
density, icorr (A/cm2)
Static 1.3
Liquid–solid impingement, 200 mg/l solids 5.8
Liquid–solid impingement, 500 mg/l solids 21.8
3.2.4. Linear polarisation
Fig. 8 shows the values of Rp ( E/ I) determined for
the five solid loadings from 0 to 500 mg/l. In comparing
the value for Rp between static conditions and impingement
with no solids there is no significant difference. However,
on addition of 100 mg/l solids to the impinging stream there
is a significant decrease in the Rp value. The largest changes
of Rp occur at the solid loadings up to 200 mg/l after which
the Rp becomes much less dependent on solid loading.
Fig. 8. Polarisation resistance (Rp) calculated from the linear polarisation measurements across a potential range of ±50 mV from the free corrosion
potential over a range of solid loadings from 0 to 500 mg/l.
3.2.5. Cathodic polarisation
Depolarisation of the cathodic reaction is clear as the
WC–Co–Cr coating is subjected to erosion–corrosion as
shown in Fig. 9. In static conditions a small region between
−0.8 and −1 V exists where the current rises much less as a
function of potential signifying some partial diffusion con-
trol. The addition of solids to the slurry stream (200 and
500 mg/l) increases the cathodic current density measured
at each potential compared to the static condition. The sig-
nificance of these curves is in the determination of the opti-
mum potential for application of CP. This will be discussed
in great detail in Section 4.
3.3. Erosion–corrosion material loss
3.3.1. Volume loss
Fig. 10 shows the total volume loss recorded for the coat-
ing and the two stainless steels at two solid loadings, 200
and 500 mg/l, respectively. As expected the stainless steels
have a lower resistance to erosion–corrosion than the cer-
met coating. The coating exhibits an enhanced performance
margin over the materials UNS S31603 and UNS S32760
as the solid loading increases. At 200 mg/l solid loading the
coating exhibited a mass loss of 64 and 76% of the UNS
S31603 and UNS S32760 value, respectively, at 500 mg/l
the figures were lower at 55 and 68%, respectively, thus in-
creasing the margin.
3.3.2. Material loss mechanisms
Fig. 11 shows the surface of the WC–Co–Cr coating
after erosion–corrosion for 8 h at two solid loadings and
three regions on the surface are clearly defined on each
surface. Region 1 is the central zone where the surface is
dulled considerably due to the erosion–corrosion damage.
This ‘dulling’ of the surface is due to the development of
craters which appear as macro pits on the surface. These are
7. 152 V.A. de Souza, A. Neville / Wear 255 (2003) 146–156
Fig. 9. Cathodic polarisation curves measured in static and liquid–solid impingement conditions.
Fig. 10. Total volume loss measured for the coating and the two stainless steels under liquid–solid impingement.
Fig. 11. Wear scar on the surface of WC–Co–Cr after exposure to the
impingement with overall surface image with three different regions.
evident on surfaces without and with CP applied and hence
are a mechanical feature of the damage. Fig. 12a shows the
boundary between the central dull region and the concen-
tric ring described as the erosion ‘halo’ (Region 2) in the
literature [22,23]. Inside Region 1 the damage reflects the
fact that impacts are nominally at high angle and it can be
seen that there is extensive brittle fracture and removal of
the hard phase particles (Fig. 12b). Region 3 is the outer af-
fected zone where damage due to impingement is still clear
but there are clear differences when compared to Region 1.
Fig. 12c shows the surface of Region 3 and it is clear that
there is directionality associated with the damage. There
is evidence of material (matrix) flow along the direction of
the flow out from the central zone. There is far less evi-
dence of hard particle removal than in Region 1 although
there are still sites where macro-cracking is observable.
8. V.A. de Souza, A. Neville / Wear 255 (2003) 146–156 153
Fig. 12. Damage in: (a) Region 1; (b) Region 2; (c) Region 3; (d) shows the form of the wear scar profile typically found on eroded surfaces of
WC–Co–Cr coating when exposed to liquid–solid impingement at 500 mg/l solids for 8 h.
Fig. 13. CP currents for WC–Co–Cr under liquid–solid impingement for 200 mg/l solids at −0.5 and −0.8 V (SCE).
Fig. 12d shows the profile of the wear scar determined from
profilometry.
3.3.3. Application of CP
Fig. 13 shows the CP currents as a function of time with
200 mg/l solids over the 8 h test period at two potentials:
−0.5 and −0.8 V. The magnitude of the current is increased
as the overpotential for the applied CP potential increases.
Also, as the solid loading increases the amount of current
required to maintain the CP potential increases as illustrated
by the total charge during CP figures in Table 5.
Table 5
Total charge during CP under impingement for 8 h period
Applied CP potential
(V) (SCE)
Total charge during CP (C)
200 mg/l solids 500 mg/l solids
−0.5 90.4 139.1
−0.8 646 812.8
9. 154 V.A. de Souza, A. Neville / Wear 255 (2003) 146–156
Fig. 14. Weight losses for WC–Co–Cr for liquid–solid impingement without and with applied CP.
Fig. 14 shows the reduction in material loss measured in
the presence of applied CP compared with the material loss
measured with no applied CP. It can be seen that there is
a significant effect at both solid loadings of applying CP at
the level of −0.8 V. At −0.5 V the effect is slightly more
complicated and will be discussed later.
4. Discussion
The use of thermal spray coatings for reducing material
degradation in tribo-corrosion environments has increased
in recent years and successful applications in pump compo-
nents, valves and other equipment subjected to impinging
solid-laden stream are commonplace. However, there is still
a need to define the limitations for WC–Co–Cr and other
cermet coatings, especially where corrosion and joint ero-
sion/corrosion mechanisms can affect performance. It has
been demonstrated in the previous work by the authors that
localised corrosion attack at carbide/matrix interfaces can
lead to loss of support for carbides and also dissolution of
carbides when the local environment becomes aggressive
during localised corrosion. In this current paper the em-
phasis is on investigating how corrosion and erosion inter-
act and the test methodology has been devised with this in
mind.
4.1. Overall performance
WC–Co–Cr from the thermal spray process investigated
in this study showed superior resistance to erosion–corrosion
than both of the stainless steels (UNS S31603 and
UNS S32760) as expected. As the conditions of the
erosion–corrosion became more severe (increased solid
loading) the difference between the cermet and stainless
steels was enhanced. Hawthorne et al. [12] found ratios of
UNS S31603/WC–Co–Cr of almost 6:1 in slurry impinge-
ment tests which is much greater than those experienced
here but it is important to note that the slurry used in their
tests was not corrosive and the solid loadings were 9.1 wt.%
compared with the 500 mg/l (0.05%) in this study and
also the difference in composition between the D-Gun and
HVOF coatings can account for the difference in wear rates.
It is apparent from the nature of the wear scar on
WC–Co–Cr (showing highest degradation at a nominal 90◦
angle) in contrast to the stainless steels, as reported else-
where [23] that the material loss mechanisms are somewhat
different and some analogies can be made from considera-
tion of ductile and brittle material behaviour as was defined
in dry erosion in the early work of Finnie [24]. Considering
the transport of particles in this dilute liquid–solid stream, it
is apparent that at the centre of the jet (Region 1 in Fig. 11)
the particles will nominally impact at 90◦. On moving out
from the centre of the jet the surface will be exposed to
impacts at a lower angle and due to squeeze film effects the
particles may not indeed impact at all. If the mechanical
degradation laws relationships for dry erosion, established
first by Finnie [24] are transferred across to liquid–solid
impingement it may be assumed that for a ductile material
the highest loss of depth will occur out from the centre
(normally at an angle of around 30◦) and for stainless steels
the “w” shape confirms this to be the case. Also, for the
more brittle WC–Co–Cr the material loss is highest at 90◦.
The “u” shape of the wear scar confirms this to be the case.
4.2. Corrosion/erosion interactions
Application of CP at −0.8 V (SCE) was effective at both
solid loadings of reducing the corrosion component of the
damage to a negligible level as was proved to be the case
in [22]. At this level of CP the erosion damage is isolated
and it can be seen that at 200 and 500 mg/l the damage is
very much dominated by erosion processes. For 200 mg/l
E/TWL is 0.836 and at 500 mg/l it is 0.877. Hence as the
10. V.A. de Souza, A. Neville / Wear 255 (2003) 146–156 155
solids level increases the damage becomes more and more
dominated by erosion processes. This was in contrast to the
situation in solids-free impingement of an HVOF WC–CoCr
coating where the damage was dominated by corrosion
and corrosion-related (synergistic) processes [20]. Erosion,
playing a large part of the damage in slurry impingement
is often the case in aggressive conditions and it has been
shown to be the same on drill bit material (Stellite X-40)
[19] but on austenitic stainless steels the opposite was the
case [23] and corrosion became a higher proportion of the
damage as the solid loading increased. This was apparently
due to the crucial repassivation events which occur on solid
impact on stainless steels and the corrosion damage is criti-
cally affected by the ability to repassivate once damage has
occurred.
In terms of corrosion it is interesting to note that the
effect of erosion processes on corrosion of the cermet is
significant and that corrosion rates are increased by a fac-
tor of 4.46 at 200 mg/l solids and 16.8 at 500 mg/l solids
compared to static corrosion rates. It is known from XPS
that Cr in the coating forms oxide (Cr2O3) which will pre-
vent substantial charge transfer [21]. It is therefore likely
that under E/C the oxide on the metal phase is removed
and corrosion (at a rate greater than in static conditions)
can proceed. Hence impingement by impacting solids will
have the effect of removing any passive film on the binder
and render the material active and enable charge transfer.
Hence the large factor of Ce is in line with what would be
expected for this type of binder. Table 6 shows the values
of the components of material loss (TWL) according to
TWL = E + C + Ce + Ec (2)
where E is the pure erosion material loss determined through
application of CP, C and Ce are the static corrosion com-
ponent and the effect of erosion on corrosion, respectively,
and Ec the effect of corrosion on erosion (often referred
to as the synergy).
Corrosion measurements under erosion–corrosion condi-
tions have been conducted in this study using polarisation
techniques and then Tafel extrapolation to evaluate the cor-
rosion current density at the free corrosion potential. The
corrosion current densities established from these measure-
ments were used to evaluate the components of corrosion
damage in Table 6. As part of this investigation Rp mea-
surements were made at various solid loadings and it was
shown that the Rp decreased as the solid loading increased.
The trend was in line with the increase icorr measured
during impingement at 200 and 500 mg/l solids. However,
Table 6
Components of material loss (mg) attributed to different degradation
processes on WC–Co–Cr under liquid–solid impingement in 3.5% NaCl
E C Ce Ec
200 mg/l 5.1 0.04 0.15 0.81
500 mg/l 11.5 0.04 0.67 0.89
there is an important consideration to be made in that the
ratio of icorr at the two solid loadings does not match the
ratio of 1/Rp values at the two solid loadings. This therefore
indicates that for Rp measurements to give a good approx-
imation to the corrosion rates then the values of βa and βc
must be established under erosion–corrosion conditions and
these cannot be routinely assumed to be constant. Otherwise
erroneously low changes in corrosion current as a function
of solid loading would be estimated.
Interestingly at −0.5 V applied CP the damage was re-
duced at the lower solid loading of 200 mg/l to a comparable
value at −0.8 V but at the higher solid loading the applied
potential of −0.5 V was not effective in reducing the cor-
rosion component of damage. Two links to electrochemical
measurements can be made in this respect. Firstly the free
corrosion potential at 500 mg/l is more negative than at
200 mg/l and hence the CP overpotential is reduced and as
such the CP efficiency would be expected to drop. Also, as
the solid loading increases the corrosion current increases
and so the amount of current required to protect the surface
increases and cannot be sustained at −0.5 V. Hence it can be
deduced that for erosion–corrosion the choice of potential is
vital.
5. Conclusions
The study has demonstrated the following:
• WC–CoCr thermal sprayed coatings can provide good
protection against wear and corrosion in liquid–solid im-
pingement when compared with stainless steels.
• The mechanisms of damage are dominated by erosion
processes but corrosion is affected by erosion processes
and is more important at the lower solid levels.
• Monitoring of corrosion rates requires care to be taken in
interpreting linear polarisation data.
• CP can offer protection from erosion–corrosion damage—
the extent of the protection depends on the erosion–
corrosion severity.
Acknowledgements
The authors acknowledge Weir Pumps Ltd., Glasgow and
Greenhey Engineering Services, England, for the financial
support provided to V.A. de Souza.
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