Samarium Cobalt 2:17 series (Sm2Co17) magnet is prepared by powder metallurgy technique. Different parameters for sintering and heat treatment process such as sintering time, temperature, furnace atmosphere and heating rate were tested in order to achieve the highest density for Samarium Cobalt 2:17 series that could be obtained. To analyze and evaluate the microstructure and particle size of fabricated magnets, scanning electron microscopy (SEM) and X-ray diffraction (XRD) tests were used. Results show that sintering temperatures and furnace atmosphere are among the most important parameters that affecting on the density of the samples and consequently the magnetic properties. It is showed that the highest density of 7.98 g/cm3 (%95 of theoretical density) has been obtained from initial particles with the size of 3 to 6 µm and sintering temperature of 11950C with a rate of 17˚C/min for 1 hr in vacuum condition.
INVESTIGATION OF OPTIMIZED PROCESS PARAMETERS ON DENSIFICATION OF SAMARIUM CO...ijeljournal
The aim of this study is to investigate the effect of different process parameters on densification of
Samarium Cobalt 1:5 series (SmCo5) magnet by powder metallurgy technique. Different parameters for
sintering and heat treatment process such as particle size, load of press, sintering time and temperature,
furnace atmosphere and heating rate were tested in order to achieve the highest density. To analyze and
evaluate the microstructure and particle size of manufactured magnets scanning electron microscopy
(SEM) and X-ray diffraction (XRD) tests were conducted. Results of different tests showed that sintering
temperature as well as furnace atmosphere is among the most important parameters affecting on final
density of the samples. Investigations illustrated that highest density could be obtained with the sintering
of green bodies which made from initial particles with the size of 3 to 6 µm in vacuum condition at 1135˚C
for 30 min by rapid heating at the shortest time.
Improving Fracture Toughness of Mullite Ceramics with Metal ReinforcementsIJRES Journal
Mullite/Metal composite ceramics were fabricated by the use of mechanical milling and pressureless sintering. Al2O3 + 10 vol.% of Co, Ni, or Ti were mixed and milled during 12 h at 300 rpm in a horizontal mill, then with the powder mixture it was conformed cylindrical samples by uniaxial pressing using 300 MPa. Pressed samples were sintered during 2 h in an electrical furnace at 1500°C. During sintered it was used an argon atmosphere inside the furnace in order to inhibit metal oxidation. XRD results indicate that alumina and metals retain its crystalline structure. Measurements of densities indicate that they were achieved relative densities between 90% and 98% in the manufacture composites. Optical microscopy observations show mullite’s microstructure with very fine and homogeneous distributions of metal particles. Used metals (Co, Ni and Ti) to reinforce mullite, have yielded favorable results improving the fracture toughness of the mullite. However, it should be made more dense materials with them to better explore this potential.
INVESTIGATION OF OPTIMIZED PROCESS PARAMETERS ON DENSIFICATION OF SAMARIUM CO...ijeljournal
The aim of this study is to investigate the effect of different process parameters on densification of
Samarium Cobalt 1:5 series (SmCo5) magnet by powder metallurgy technique. Different parameters for
sintering and heat treatment process such as particle size, load of press, sintering time and temperature,
furnace atmosphere and heating rate were tested in order to achieve the highest density. To analyze and
evaluate the microstructure and particle size of manufactured magnets scanning electron microscopy
(SEM) and X-ray diffraction (XRD) tests were conducted. Results of different tests showed that sintering
temperature as well as furnace atmosphere is among the most important parameters affecting on final
density of the samples. Investigations illustrated that highest density could be obtained with the sintering
of green bodies which made from initial particles with the size of 3 to 6 µm in vacuum condition at 1135˚C
for 30 min by rapid heating at the shortest time.
Improving Fracture Toughness of Mullite Ceramics with Metal ReinforcementsIJRES Journal
Mullite/Metal composite ceramics were fabricated by the use of mechanical milling and pressureless sintering. Al2O3 + 10 vol.% of Co, Ni, or Ti were mixed and milled during 12 h at 300 rpm in a horizontal mill, then with the powder mixture it was conformed cylindrical samples by uniaxial pressing using 300 MPa. Pressed samples were sintered during 2 h in an electrical furnace at 1500°C. During sintered it was used an argon atmosphere inside the furnace in order to inhibit metal oxidation. XRD results indicate that alumina and metals retain its crystalline structure. Measurements of densities indicate that they were achieved relative densities between 90% and 98% in the manufacture composites. Optical microscopy observations show mullite’s microstructure with very fine and homogeneous distributions of metal particles. Used metals (Co, Ni and Ti) to reinforce mullite, have yielded favorable results improving the fracture toughness of the mullite. However, it should be made more dense materials with them to better explore this potential.
Synthesis and Study on Structural, Morphological and Magnetic properties of n...Editor IJCATR
Mn3O4 nanoparticles were prepared by co-precipitation method followed by annealing of samples at 300 °C for 2 hours. The
samples were characterized to find the structural, functional, optical, morphological, compositional and magnetic properties by PXRD,
FTIR, Micro-Raman, HRSEM, TEM, XPS, EDX and VSM respectively. Structural studies by PXRD indicate that the annealing has
strongly influenced the phase transition showing two coexisting phases of Mn2O3 and Mn3O4. Micro-Raman spectra showed the
presence of A1g mode of vibration corresponding to Mn3O4 phase. Magnetic studies of the as synthesized Mn3O4 nanoparticles depict
paramagnetic behavior at room temperature.
Structural, Electrical and Magnetotransport properties of La0.7Ca0.2Sr0.1MnO3...IOSR Journals
The sample of manganite perovskite oxide La0.7Ca0.2Sr0.1MnO3 has been prepared by solution combustion synthesis. The synthesized sample has been pelletized and further sintered at 8000C for 8 hours. The XRD pattern reveals that the samples are of single phase nature with orthorhombic structure and the diffraction patterns can be indexed with the pbnm space groups. The crystallite sizes calculated from broadening of XRD peaks using Scherrer’s formula were about 18 nm. Resistivity measurements were performed in the temperature range 2K under 3, 5, 10 and 14 T field using PPMS. Magnetoresistance shows a shift in metal-insulator transition temperature from ~213 K at zero field to ~250 K at 14T. MR value decreases as the temperature increases and at 300 K maximum value of MR is found to be ~ 22% for an applied field of 14 T. MR of ~ 28% is observed at 230 K. MR of ~ 35% is observed at 150 K in an applied field of 14 T and MR has negative sign
Carbon Nanotubes Effect for Polymer Materials on Break Down Voltage IJECEIAES
Epoxy resin composites reinforced to different types of carbon nano-particles have been fabricated. Carbon black (20, 30 and 40 wt. %), graphene (0.5 to 4 wt. %) and carbon nanotubes (CNT) (0.5 to 2 wt. %) were added with different weight percentages to epoxy. The dielectric strength of composites was tested in several conditions such as (dry, wet, low salinity and high salinity). The mechanical characterization showed that the nano-composite Polymer enhanced by using these particles in the tensile strength. Thermal gravimetric analysis shows effect of these nano-particles on the thermal structure of epoxy resin. Scanning Electron Microscopic test is used to characterize the dispersion of carbon nano-particles and to analysis the fractured parts in the nano scale.
The main objective of my research project is the development of an innovative method of dielectric constant reduction with the use of controlled internal porosity in LTCC structures. For this purpose, an experimental glass-ceramic green tape (doped with starch as pore former) was created.
Effect of sintering time on the particle size and dielectric properties of La...ijceronline
International Journal of Computational Engineering Research (IJCER) is dedicated to protecting personal information and will make every reasonable effort to handle collected information appropriately. All information collected, as well as related requests, will be handled as carefully and efficiently as possible in accordance with IJCER standards for integrity and objectivity.
Study on hardening mechanisms in aluminium alloysIJERA Editor
The Al-Zn-Mg alloys are most commonly used age-hardenable aluminium alloys. The hardening mechanism is
further enhanced in addition of Sc. Sc additions to aluminium alloys are more promising. Due to the
heterogeneous distribution of nano-sized Al3Sc precipitates hardening effect can be accelerated. Mainly,
highlight on hardening mechanism in Al-Zn-Mg alloys with Sc effect is to study. In addition, several
characterisations have been done to age-hardening measurements at elevated temperatures from 120oC to 180
oC. The ageing kinetics has also been calculated from Arrhenius equation. Furthermore, friction stir processing
(FSP) can be introduced to surface modification process and hardened the cast aluminium alloys. In this study,
hardening mechanism can be evaluated by Vicker’s hardness measurement and mechanical testing is present
task.
Study on hardening mechanisms in aluminium alloysIJERA Editor
The Al-Zn-Mg alloys are most commonly used age-hardenable aluminium alloys. The hardening mechanism is
further enhanced in addition of Sc. Sc additions to aluminium alloys are more promising. Due to the
heterogeneous distribution of nano-sized Al3Sc precipitates hardening effect can be accelerated. Mainly,
highlight on hardening mechanism in Al-Zn-Mg alloys with Sc effect is to study. In addition, several
characterisations have been done to age-hardening measurements at elevated temperatures from 120oC to 180
oC. The ageing kinetics has also been calculated from Arrhenius equation. Furthermore, friction stir processing
(FSP) can be introduced to surface modification process and hardened the cast aluminium alloys. In this study,
hardening mechanism can be evaluated by Vicker’s hardness measurement and mechanical testing is present
task.
SiC and ZrO2 Weigh Percentage Effects on Microstructure of Al Based Matrix Co...INFOGAIN PUBLICATION
SiC and ZrO2 particle are succesfully reaction synthesized from powder of Al, ZrO2 and SiC using spark plasma sintering method. The XRD of sintered composite and microstructure of the aas-sintered products. With the ZrO2 content increasing, the grains are remarkably refined and the and the ZrO2 and nano SiC particles are dispersing more uniformly in Al matrix, forming a homogeneous structure with the least porosity.
Preparation and Investigation on Properties of Cryogenically Solidified Nano ...IJERA Editor
In the present work, AL-alloy containing 12% silicon (LM 13) matrix nano composites were fabricated in sand moulds by using copper end blocks of copper end chill thickness 10 &15 nm with cryogenic effect . The size of the reinforcement (NanoZro2) ranges from 50-80nm being added ranges from 3 to 15 wt % in steps of 3 wt % . Cryogenically solidified Nano Metal Matrix Composites were compressed by using hydraulic compression machine. Specimens were prepared according to ASTM standards and tested for their strength, hardness and fracture toughness. Micro structural studies of the fabricated Nano Composites indicate that there is uniform distributions of reinforcements in the matrix materials (LM 13). An increasing trend of hardness, UTS & fracture toughness has been observed. The best results have been obtained at 12 wt %. The results were further justified by comparing two copper end chill thickness 10 &15 mm. Finally the Volumetric Heat Capacity of the cryo-chill is identified as an important parameter which affects mechanical properties.
Synthesis and Study on Structural, Morphological and Magnetic properties of n...Editor IJCATR
Mn3O4 nanoparticles were prepared by co-precipitation method followed by annealing of samples at 300 °C for 2 hours. The
samples were characterized to find the structural, functional, optical, morphological, compositional and magnetic properties by PXRD,
FTIR, Micro-Raman, HRSEM, TEM, XPS, EDX and VSM respectively. Structural studies by PXRD indicate that the annealing has
strongly influenced the phase transition showing two coexisting phases of Mn2O3 and Mn3O4. Micro-Raman spectra showed the
presence of A1g mode of vibration corresponding to Mn3O4 phase. Magnetic studies of the as synthesized Mn3O4 nanoparticles depict
paramagnetic behavior at room temperature.
Structural, Electrical and Magnetotransport properties of La0.7Ca0.2Sr0.1MnO3...IOSR Journals
The sample of manganite perovskite oxide La0.7Ca0.2Sr0.1MnO3 has been prepared by solution combustion synthesis. The synthesized sample has been pelletized and further sintered at 8000C for 8 hours. The XRD pattern reveals that the samples are of single phase nature with orthorhombic structure and the diffraction patterns can be indexed with the pbnm space groups. The crystallite sizes calculated from broadening of XRD peaks using Scherrer’s formula were about 18 nm. Resistivity measurements were performed in the temperature range 2K under 3, 5, 10 and 14 T field using PPMS. Magnetoresistance shows a shift in metal-insulator transition temperature from ~213 K at zero field to ~250 K at 14T. MR value decreases as the temperature increases and at 300 K maximum value of MR is found to be ~ 22% for an applied field of 14 T. MR of ~ 28% is observed at 230 K. MR of ~ 35% is observed at 150 K in an applied field of 14 T and MR has negative sign
Carbon Nanotubes Effect for Polymer Materials on Break Down Voltage IJECEIAES
Epoxy resin composites reinforced to different types of carbon nano-particles have been fabricated. Carbon black (20, 30 and 40 wt. %), graphene (0.5 to 4 wt. %) and carbon nanotubes (CNT) (0.5 to 2 wt. %) were added with different weight percentages to epoxy. The dielectric strength of composites was tested in several conditions such as (dry, wet, low salinity and high salinity). The mechanical characterization showed that the nano-composite Polymer enhanced by using these particles in the tensile strength. Thermal gravimetric analysis shows effect of these nano-particles on the thermal structure of epoxy resin. Scanning Electron Microscopic test is used to characterize the dispersion of carbon nano-particles and to analysis the fractured parts in the nano scale.
The main objective of my research project is the development of an innovative method of dielectric constant reduction with the use of controlled internal porosity in LTCC structures. For this purpose, an experimental glass-ceramic green tape (doped with starch as pore former) was created.
Effect of sintering time on the particle size and dielectric properties of La...ijceronline
International Journal of Computational Engineering Research (IJCER) is dedicated to protecting personal information and will make every reasonable effort to handle collected information appropriately. All information collected, as well as related requests, will be handled as carefully and efficiently as possible in accordance with IJCER standards for integrity and objectivity.
Study on hardening mechanisms in aluminium alloysIJERA Editor
The Al-Zn-Mg alloys are most commonly used age-hardenable aluminium alloys. The hardening mechanism is
further enhanced in addition of Sc. Sc additions to aluminium alloys are more promising. Due to the
heterogeneous distribution of nano-sized Al3Sc precipitates hardening effect can be accelerated. Mainly,
highlight on hardening mechanism in Al-Zn-Mg alloys with Sc effect is to study. In addition, several
characterisations have been done to age-hardening measurements at elevated temperatures from 120oC to 180
oC. The ageing kinetics has also been calculated from Arrhenius equation. Furthermore, friction stir processing
(FSP) can be introduced to surface modification process and hardened the cast aluminium alloys. In this study,
hardening mechanism can be evaluated by Vicker’s hardness measurement and mechanical testing is present
task.
Study on hardening mechanisms in aluminium alloysIJERA Editor
The Al-Zn-Mg alloys are most commonly used age-hardenable aluminium alloys. The hardening mechanism is
further enhanced in addition of Sc. Sc additions to aluminium alloys are more promising. Due to the
heterogeneous distribution of nano-sized Al3Sc precipitates hardening effect can be accelerated. Mainly,
highlight on hardening mechanism in Al-Zn-Mg alloys with Sc effect is to study. In addition, several
characterisations have been done to age-hardening measurements at elevated temperatures from 120oC to 180
oC. The ageing kinetics has also been calculated from Arrhenius equation. Furthermore, friction stir processing
(FSP) can be introduced to surface modification process and hardened the cast aluminium alloys. In this study,
hardening mechanism can be evaluated by Vicker’s hardness measurement and mechanical testing is present
task.
SiC and ZrO2 Weigh Percentage Effects on Microstructure of Al Based Matrix Co...INFOGAIN PUBLICATION
SiC and ZrO2 particle are succesfully reaction synthesized from powder of Al, ZrO2 and SiC using spark plasma sintering method. The XRD of sintered composite and microstructure of the aas-sintered products. With the ZrO2 content increasing, the grains are remarkably refined and the and the ZrO2 and nano SiC particles are dispersing more uniformly in Al matrix, forming a homogeneous structure with the least porosity.
Preparation and Investigation on Properties of Cryogenically Solidified Nano ...IJERA Editor
In the present work, AL-alloy containing 12% silicon (LM 13) matrix nano composites were fabricated in sand moulds by using copper end blocks of copper end chill thickness 10 &15 nm with cryogenic effect . The size of the reinforcement (NanoZro2) ranges from 50-80nm being added ranges from 3 to 15 wt % in steps of 3 wt % . Cryogenically solidified Nano Metal Matrix Composites were compressed by using hydraulic compression machine. Specimens were prepared according to ASTM standards and tested for their strength, hardness and fracture toughness. Micro structural studies of the fabricated Nano Composites indicate that there is uniform distributions of reinforcements in the matrix materials (LM 13). An increasing trend of hardness, UTS & fracture toughness has been observed. The best results have been obtained at 12 wt %. The results were further justified by comparing two copper end chill thickness 10 &15 mm. Finally the Volumetric Heat Capacity of the cryo-chill is identified as an important parameter which affects mechanical properties.
This work studied the effect of applying pulse current
(ton=off=1s) on the electrodeposition of silver nanoparticles on
carbon sphere surface as a substrate. The electrolyte is made of 0.1
M KNO3, 0.1 M KCN and 0.01M AgNO3. The pH value has been
adjusted in the alkaline region of 9.1 with the help of K(NO3)
addition. Experiments were carried out at room temperature for
periods up to 12 minutes. The cell is fitted with a mechanical stirrer
to keep the electrolyte in a dynamic state. Product(s) was
characterized with the help of SEM and EDX and field emission.
Results obtained show that silver nanoparticles has successfully
electrodeposited under pulse current conditions with a particle size
of 100–400 nm after 2 minutes. Deposition takes place on certain
accessible sites of the carbon surface of the substrate forming a
monolayer of scattered silver nanoparticles. Formation of macro
particles with larger diameter and multilayer in thickness takes
place with continuous deposition of silver nanoparticles on the
formerly deposited silver. Pulse current helps management of the
monolayer deposition as compared to the steady DC application
with respect to particle diameter and number of layers.
Electrospun Nanofibers Reinforced Aluminium Matrix Composites, A Trial to Imp...IJAMSE Journal
A comparison between TiO2 nanofibers and carbon nanofibers as fibers reinforced metal matrix composites with respect to mechanical properties improvements have been made in this paper. Al and Mg have been chosen as metal matrices. The used carbon and ceramic nanofibers (Titanium Oxide) were successfully synthesized using electrospinning technique. Various weight percentage of calcined
electrospun TiO2 and carbon nanofibers (1, 3, 5 and 10%) were mixed with metal matrix and fabricated by route of powder metallurgy using High Frequency Induction heat Sintering (HFIHS). Mechanical properties of the sintered composites have been investigated. The manufactured pellets were tested for compression test, hardness and microstructures by the field emission scanning electron microscopes (FESEM), which reveals the homogeneous distribution of nanofibers in the Al/Mg matrices. In addition,
energy-dispersive X-ray spectroscopy (EDS) was employed to obtain the chemical analysis of each composite. The result shows that, the ultimate compressive strength increased to 415 MPa at 5% TiO2, which is 13.5% more than the pure Al. The hardness increased up to 64% in case of using the ceramic nanofibers as reinforcement. While using CNFs as reinforcement to the Al matrix deteriorates the
mechanical properties.
6th International Conference on Machine Learning & Applications (CMLA 2024)ClaraZara1
6th International Conference on Machine Learning & Applications (CMLA 2024) will provide an excellent international forum for sharing knowledge and results in theory, methodology and applications of on Machine Learning & Applications.
Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...Dr.Costas Sachpazis
Terzaghi's soil bearing capacity theory, developed by Karl Terzaghi, is a fundamental principle in geotechnical engineering used to determine the bearing capacity of shallow foundations. This theory provides a method to calculate the ultimate bearing capacity of soil, which is the maximum load per unit area that the soil can support without undergoing shear failure. The Calculation HTML Code included.
Student information management system project report ii.pdfKamal Acharya
Our project explains about the student management. This project mainly explains the various actions related to student details. This project shows some ease in adding, editing and deleting the student details. It also provides a less time consuming process for viewing, adding, editing and deleting the marks of the students.
CW RADAR, FMCW RADAR, FMCW ALTIMETER, AND THEIR PARAMETERSveerababupersonal22
It consists of cw radar and fmcw radar ,range measurement,if amplifier and fmcw altimeterThe CW radar operates using continuous wave transmission, while the FMCW radar employs frequency-modulated continuous wave technology. Range measurement is a crucial aspect of radar systems, providing information about the distance to a target. The IF amplifier plays a key role in signal processing, amplifying intermediate frequency signals for further analysis. The FMCW altimeter utilizes frequency-modulated continuous wave technology to accurately measure altitude above a reference point.
Cosmetic shop management system project report.pdfKamal Acharya
Buying new cosmetic products is difficult. It can even be scary for those who have sensitive skin and are prone to skin trouble. The information needed to alleviate this problem is on the back of each product, but it's thought to interpret those ingredient lists unless you have a background in chemistry.
Instead of buying and hoping for the best, we can use data science to help us predict which products may be good fits for us. It includes various function programs to do the above mentioned tasks.
Data file handling has been effectively used in the program.
The automated cosmetic shop management system should deal with the automation of general workflow and administration process of the shop. The main processes of the system focus on customer's request where the system is able to search the most appropriate products and deliver it to the customers. It should help the employees to quickly identify the list of cosmetic product that have reached the minimum quantity and also keep a track of expired date for each cosmetic product. It should help the employees to find the rack number in which the product is placed.It is also Faster and more efficient way.
NUMERICAL SIMULATIONS OF HEAT AND MASS TRANSFER IN CONDENSING HEAT EXCHANGERS...ssuser7dcef0
Power plants release a large amount of water vapor into the
atmosphere through the stack. The flue gas can be a potential
source for obtaining much needed cooling water for a power
plant. If a power plant could recover and reuse a portion of this
moisture, it could reduce its total cooling water intake
requirement. One of the most practical way to recover water
from flue gas is to use a condensing heat exchanger. The power
plant could also recover latent heat due to condensation as well
as sensible heat due to lowering the flue gas exit temperature.
Additionally, harmful acids released from the stack can be
reduced in a condensing heat exchanger by acid condensation. reduced in a condensing heat exchanger by acid condensation.
Condensation of vapors in flue gas is a complicated
phenomenon since heat and mass transfer of water vapor and
various acids simultaneously occur in the presence of noncondensable
gases such as nitrogen and oxygen. Design of a
condenser depends on the knowledge and understanding of the
heat and mass transfer processes. A computer program for
numerical simulations of water (H2O) and sulfuric acid (H2SO4)
condensation in a flue gas condensing heat exchanger was
developed using MATLAB. Governing equations based on
mass and energy balances for the system were derived to
predict variables such as flue gas exit temperature, cooling
water outlet temperature, mole fraction and condensation rates
of water and sulfuric acid vapors. The equations were solved
using an iterative solution technique with calculations of heat
and mass transfer coefficients and physical properties.
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
(CNN)s, to adversarial attacks and presents a proactive training technique designed to counter them. We
introduce a novel volumization algorithm, which transforms 2D images into 3D volumetric representations.
When combined with 3D convolution and deep curriculum learning optimization (CLO), itsignificantly improves
the immunity of models against localized universal attacks by up to 40%. We evaluate our proposed approach
using contemporary CNN architectures and the modified Canadian Institute for Advanced Research (CIFAR-10
and CIFAR-100) and ImageNet Large Scale Visual Recognition Challenge (ILSVRC12) datasets, showcasing
accuracy improvements over previous techniques. The results indicate that the combination of the volumetric
input and curriculum learning holds significant promise for mitigating adversarial attacks without necessitating
adversary training.
Overview of the fundamental roles in Hydropower generation and the components involved in wider Electrical Engineering.
This paper presents the design and construction of hydroelectric dams from the hydrologist’s survey of the valley before construction, all aspects and involved disciplines, fluid dynamics, structural engineering, generation and mains frequency regulation to the very transmission of power through the network in the United Kingdom.
Author: Robbie Edward Sayers
Collaborators and co editors: Charlie Sims and Connor Healey.
(C) 2024 Robbie E. Sayers
AKS UNIVERSITY Satna Final Year Project By OM Hardaha.pdf
Investigation of Optimized Process Parameters on Densification of Samarium Cobalt 2:17 Series (SM2CO17) Magnets
1. International Journal of Electromagnetic ( IJEL ),Vol 2, No 1
1
INVESTIGATION OF OPTIMIZED PROCESS
PARAMETERS ON DENSIFICATION OF
SAMARIUM COBALT 2:17 SERIES (SM2CO17)
MAGNETS
Alireza Taherizadeh1
, Sirus. Javadpour1
and Habibollah Alikhani2
1
School of Materials Science and Engineering, Shiraz University, Shiraz, Iran
2
School of Material Science and Engineering, Sahand University of Technology. Iran
ABSTRACT
Samarium Cobalt 2:17 series (Sm2Co17) magnet is prepared by powder metallurgy technique. Different
parameters for sintering and heat treatment process such as sintering time, temperature, furnace
atmosphere and heating rate were tested in order to achieve the highest density for Samarium Cobalt 2:17
series that could be obtained. To analyze and evaluate the microstructure and particle size of fabricated
magnets, scanning electron microscopy (SEM) and X-ray diffraction (XRD) tests were used. Results show
that sintering temperatures and furnace atmosphere are among the most important parameters that
affecting on the density of the samples and consequently the magnetic properties. It is showed that the
highest density of 7.98 g/cm3
(%95 of theoretical density) has been obtained from initial particles with the
size of 3 to 6 µm and sintering temperature of 11950
C with a rate of 17˚C/min for 1 hr in vacuum condition.
KEYWORDS
Samarium Cobalt, rare earth permanent magnet, powder metallurgy, heat treatment.
1. INTRODUCTION
Samarium Cobalt (Sm2Co17) magnets are ideal materials for applications such as microwave
tubes, sensors and servo motors because of their high magnetic properties, thermal stability and
appropriate corrosion resistance. Among all the rare earth permanent magnets, Samarium Cobalt
2:17 series have the highest Curie temperature and the maximum value of saturation
magnetization at high temperatures [1-8]. Samarium Cobalt magnets are usually manufactured by
powder metallurgy technique. They are brittle and show a high thermal and corrosion resistance
[10-13]. They are also relatively expensive because of the rarity of the elements in their
composition. Manufacturing process of Samarium Cobalt by powder metallurgy is as following:
Preparing initial alloy, powder milling, mixing powder, pressing and magnetic orientation,
sintering and homogenization process, heat treatment, machining operation and finally
magnetization [9,10,14,15]. Adding Iron to a limit extent to this composition by replacing Cobalt
atoms increases the maximum energy BH)max, magnetic saturation (Ms) and magnetic remanence
(Br), and it is because of Iron atoms have higher magnetic moments than the Cobalt atoms.
However, if the limit is exceeded, magnetic coercivity would be decreased. The Curie
temperature reduction is one of the problems that happen when Iron is added to the main
composition [18-23]. Copper in the composition makes it more difficult for domain walls to move
thus increases the magnetic saturation. Copper also decreases the eutectic temperature of the
composition [10,24,25]. Adding Zirconium increases anisotropy and magnetic coercivity,
however adding too much will also reduce the magnetic properties [26,27].
2. International Journal of Electromagnetic ( IJEL ),Vol 2, No 1
2
Grain size and dislocation density are two important microstructural factors which affect the
magnetic properties. It has been proved experimentally that magnetic coercivity has a direct
relation with 0.5
(where is dislocation density) [28,29]. However, when the grain size is small,
grain boundaries increase and it greatly improves coercivity due to the fact that grain boundaries
lock magnetic domain walls. Therefore by reducing the size of particles, single domains are
produced and consequently the magnetic coercivity decreases to zero. In this case a
superparamagnetic material is made [30,31].
In Samarium Cobalt 2:17 series the main matrix is the Sm2(CoFe)17, a phase with rhombohedral
unit cell. The matrix increases the magnetic saturation of the system which is surrounded by
Sm(CoFe)5, a Cu-rich phase with hexagonal unit cell. This grain boundary phase increases the
magnetic coercivity of the system which works by domain boundaries pinning mechanism.
Nevertheless, both cellular and lamellar phases with hexagonal unit cell also exist at phase
boundaries. A Zr-rich phase is precipitated on cellular phase. This phase also makes an easy
diffusion path for Copper atoms motion [32-39].
It has been reported that density of a sample has direct proportion to magnetic properties.
Achieving a high dense body requires some factors such as apparent density, particle size, particle
size distribution, particle shape, powder purity and etc [40]. In this paper the effective parameters
such as size of the powders, pressing load, furnace atmosphere, heating rate, sintering time and
temperature and heat treatment cycles on developing a full dense Samarium Cobalt 2:17 series
magnet were investigated. The theoretical density of SmCo magnets have been reported 8.2-8.4
gr/cm3
[42]. In each step of fabrication, the density was measured by Archimedes method
precisely.
2. EXPERIMENTAL
2.1. Analyzing the powders
X-ray fluorescence (XRF) analysis (BRUKER, S4PIONEER, Germany) using Rhodium anode
was used to determine the elements and the weight percent of them which are existing in primary
material. Results are shown in table 1.
Table1. Result of element analysis of initial compound 2:17 series
Phases available in the powders and samples were determined by X- ray diffraction (XRD)
analysis (Bruker, D8 advance, Germany) using Cu Kα radiation (λ=1.5406 Å), equipped with
X'Pert HighScore for data analyzing.
3. International Journal of Electromagnetic ( IJEL ),Vol 2, No 1
3
Size and shape of particles were examined by scanning electron microscopy (SEM; stereo SCAN,
S360 version V03.03, England). The powders were sputtered by gold in order to improve the
quality of SEM micrographs.
2.2. Development of the samples
To make a single domain Samarium Cobalt magnet by powder metallurgy technique, initial size
of powders should be at least less than 10 µm. Ball milling was performed in a planetary mill
having steel balls with diameter 10 and 20 mm. This process was done under the Argon
atmosphere with purity of 99.9% and velocity of 350-450 rpm for 1-2 hours. The powder/ball
weight ratio was set from 1 to 20. Then, samples were formed with a hydraulic uniaxial press
with the pressure of 40 to 60 kg/cm2
in the presence of magnetic field with intensity of 1.5 to 2
Tesla to align the magnetic particles [18,27,32,42-44]. Afterward, samples were encapsulated in
the vacuumed high purity quartz tubes for sintering and homogenization process.
2.3 Sintering, homogenization and heat treatment processes of the samples
Sintering process of Samarium Cobalt 2:17 series magnet took place at a temperature range of
1180-1250 ˚C for different time intervals. After sintering, homogenization process took placed in
order to form the secondary phases with composition of SmCo5 throughout the matrix phase of
the Sm2Co17. The temperature of this process was about 15-25˚C lower than sintering
temperature. Immediately after homogenization process, quenching was performed in a cold
water to prevent the decomposition of secondary phase. Next, Samples were heated up to 850˚C
and kept at this temperature for 8 hours, finally the temperature reduced to 400˚C during 11
hours. These heat treatments were done for precipitating the Cu-rich phase on matrix grain
boundaries enhancing the magnetic remanence [45-47].
3. RESULTS AND DISCUSSION
3.1. Effect of particle size on final density
Size of initial powder and size distributions are two effective factors on densification. The coarse
particles increase porosity size; therefore, density would be decreased. Achieving a single domain
particle is desirable. Since the particles with average size of 5 µm have single domain behavior
[44,50], milling was done on the powders to reach to this particle size. Image Analyzer software
was used to obtain the particle size distribution of the initial powders. The results from SEM
micrographs Fig. 1 and 2 show that most of the green powder size were between 20 to 40 µm.
Milling process was continued to obtain single domain grains with size of 3 to 6 µm [18].
Afterward, pressing was performed in the presence of a magnetic field. It aligned all the particles
that their easy axis had the same direction of applied magnetic field in a specific direction. Then,
sintering was done at 1200˚C with 15ºC/min heating rate and 1 hr soaking time. After pressing
and sintering process density of the samples were measured. Table 2 shows the effects of particle
size on final density of the samples. The results show that the 2:17 series powders, milling for 2
hours at 400 rpm have the best result. SEM micrographs show that the shapes of particles were
changed to spherical during milling process. Spherical shape is more suitable for pressing and has
less and smaller porosities, hence better density would be obtained.
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Table2. Effect of particle size on final density of 2:17 series
Fig1. SEM micrographs of green powder of 2:17 series before milling (magnification:1000)
Fig 2. SEM micrographs of green powder of 2:17 series after two hours milling (magnification:1000)
3.2. Effect of pressing pressure
Pressing pressure is one of the important parameters affecting the green and final density of the
sample. Low pressing pressure decreases the density and high pressing pressure makes problems
such as rapid degradation of the mold, misaligning of the powder and cracking the sample.
Therefore, choosing the optimum pressure is necessary. In this way, different pressures were
tested to determine the optimum pressure and results are showed in table 3 versus final density of
the samples. Results show that the appropriate pressure is 50 kg/cm2
. Pressures above 50 kg/cm2
would make crack in the sample or decreases the final density and pressures less than 50 kg/cm2
may prevent densification in particles and reduce the final density of the samples.
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Table3. Relation of pressing pressure versus final density of 2:17 series
3.3. Effect of furnace atmosphere on final density
Diffusion in solids significantly increases at high temperature; therefore, unwanted phases may be
formed or the formation of desired phases may be prevented. This phenomenon is very important
for Samarium Cobalt magnets due to the high chemical activity of elements in their composition
[9,10]. For this purpose, samples were sintered at 1200˚C for 60 minutes under four different
atmospheric conditions. In the first case, sintering process took place under air atmosphere and
then quenched in cold water. In this case, the measured density was 5.20 g/cm3
. In the next case,
sample was sintered under hydrogen atmosphere. Since there was no possibility of quenching
owing to hydrogen atmosphere, sample was cooled in the furnace. The sample appearance was
good at first but within a few days sample was fully destroyed because of the formation of cracks.
The final density was decreased to 4.63 g/cm3
. In the third case, sample was placed in quartz tube
and sintered under argon atmosphere with purity of 99.999%. In this case, the measured density
was 7.67 g/cm3
. In the last case, sample was placed in quartz tube with vacuum conditions. The
density was increased to 7.95 g/cm3
. Because of the high reactivity of elements in the
composition such as Samarium and Zirconium, in the first case the surface was completely
oxidized. Surface oxidation can be considered as important cause for the coercive force loss of
powders. Due to the presence of open pores or microcracks, the oxidation rate of massive bodies
can be increased. In the second case because of high tendency of rare earth elements to absorb
hydrogen at high temperature and releasing hydrogen from pores during cooling [45], sample was
bloated and eventually destroyed. For the third case sublimation of slight percentage of alloying
elements such as Samarium and accumulation of water vapor in the powders as well as argon gas
at high temperature increases vapor pressure in quartz tube so that high pressure gases penetrated
into the pores of sample and prevent fully densification. Therefore, the vacuum is the best choice
for high temperature process.
3.4. Effect of heating rate on final density
Thermal shock, thermal expansion and outgassing process mainly have been discussed elsewhere,
when studying heating rate of Samarium Cobalt magnet [44]. Apart from these parameters, grain
growth with increasing time and temperature are two other important issues. In permanent
magnets based on rare earth elements which magnetic properties are based on domain walls
pinning mechanism, grain growth should be prevented through reducing time and temperature of
sintering process [51]. In order to obtain appropriate heating rate, the thermal process of
Samarium Cobalt 2:17 series was conducted in three different conditions. The temperature of the
samples A, B and C was raised from room temperature to 1200˚C in 190, 130 and 70 minutes
respectively. They were kept at this temperature for 1 hour. Figure 3 showed that the samples can
be reached to appropriate density by rapid heating. If heating rate would be too slow, desired
density could not be obtained. Higher heating rate would prevent Samarium sublimation and
decreases inner pressure of the tube so that makes it possible to reach higher density.
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Fig3. Effect of heating rate on final density of Samarium Cobalt 2:17 series, sample A, B and C
3.5. Effect of sintering temperature on final density
Sintering helps to homogenize the microstructure and increase the densification of samples.
Sintering time and temperature have many effects on grain size [51]. In order to analyze effects of
sintering temperature on final density and also choosing the most appropriate temperature,
samples were sintered at 5 different temperatures between 1180 to 1250˚C for 1 hour at same
conditions.
In the first case, sintering process took place by heating the sample to 1250˚C. The sample lost its
shape totally and the density was 7.05 g/cm3
. In the second case, sintering took place by heating
the sample to 1220˚C. The sample deformed from its original shape and the density was 7.75
g/cm3
. In the next case, sintering took place by heating the sample to 1205˚C. In addition, only
the edge of sample lost their original shape and the density measured 7.90 g/cm3
. Afterward, for
the next one, sintering took place by heating the sample to 1195˚C. The sample retained its
original shape and the density increased to 7.97 g/cm3
. Finally, for the last case, sintering took
place by heating the sample to 1180˚ C. In this sense, the sample also retained its original shape
but the density decreased to 7.91 g/cm3
. One can see from fig. 4 that in low sintering
temperatures, high density has been obtained. By increasing sintering time and temperature, grain
size increases more than the single domain size. The sample which sintered at 1195˚C had higher
density than all samples, so it can be concluded that the best sintering temperature for Samarium
Cobalt 2:17 series is 1195˚C.
Fig4. Final density of Samarium Cobalt 2:17 series based on sintering temperature
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3.6. Effect of homogenization temperature on final density
The purpose of homogenization is to produce highly supersaturated single phase alloy. The
solution temperature has a main effect on coercivity of Samarium Cobalt magnets. The
relationship between diffusion coefficient D and temperature T can be described as in Eq.(1):
D=D0e-Q/RT
(1)
Where, D0 is a constant, Q is activation energy and R is gas constant. With the same solution
time, higher T leads to higher D, which is beneficial for the solution of different phases and is
easier to obtain a highly supersaturated single phase.
Homogenization process took place in order to make a fully Sm2(CoFe)17 matrix in the sample.
Homogenization temperature is usually 15 to 25˚C lower than sintering temperature [45]. To
study the effect of homogenization temperature on final density and choosing the best
temperature, samples were sintered at 1195˚C for 1hour and kept at five different homogenizing
temperatures between 1165 to 1180˚C for another 1 hour.
First sample, homogenized at 1185˚C. In this case density was 7.80 g/cm3
. For the second one,
sample homogenized at 1180˚C and the density reached to 7.80 g/cm3
. In the next case, sample
was homogenized at 1175˚C and the density increased to 7.93 g/cm3
. In the fourth case, sample
homogenized at 1170˚C and the density decreased to 7.83 g/cm3
. Finally, the last sample was
homogenized at 1165˚C and the density reached to its minimum at 7.76 g/cm3
. Consequently, a
temperature of 1175˚C was found to be the best homogenizing temperature.
3.7. Heat treatments
Sintering and heat treatment are the most important steps in the production of sintered Samarium
Cobalt magnets. The aim of sintering is, on one side, achievement of a high density without
opened connecting pores whereas, on the other hand, the growth of crystal grains should be
avoided. Open pores cause intrinsic oxidation and, therefore, reduce the magnetic remanence. The
growth of crystal grains directly reduces the coercivity, making the nucleation of reversed
domains easier. The heat treatment after sintering must be chosen to correspond to the chemical
composition of the alloy, and its purpose is to obtain a microstructure that improves coercivity.
Magnetic remanence at the end of homogenization process reaches to its required value. In
addition, heat treatments should be done in order to increase the coercivity of the samples. In fact
before quenching the solid is composed of single 2:17 phase which has low value of coercivity
and energy product, so that a heat treatment of 850˚C for 8 hours was employed on the quenched
sample to form a multiphase solid with cellular microstructure around the grain boundaries [46].
Afterward, the temperature reduced to 400˚C for 11 hours. Slow cooling may form some deposits
around domain walls [47]. Figure 5 represents the whole procedure for heat treatment of
Samarium Cobalt 2:17 series magnets.
Fig5. Typical temperature profile for sintering and heat treatment for Sm2Co17 [27].
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3.8. Phase analysis of Samarium Cobalt 2:17 series
Figure 6 represented the result of XRD patterns of Samarium Cobalt 2:17 series initial
composition. It shows that SmCo5 and Sm2Co17 phases exist in the powders.
Fig6. XRD analysis of initial composition of Samarium Cobalt 2:17 series magnet
Sintering of Samarium Cobalt permanent magnets was applied for integrating and densification of
green bodies. After sintering, homogenization is needed to uniform the microstructure. As can be
seen in fig. 7, after sintering and homogenization process represents that Sm2Co17 phase has
formed in samples [45]. Fig 8 represents that after heat treating in addition to Sm2Co17 phase,
SmCo5 phase also has been formed. The combination of these two phases causes the pinning
mechanism of magnetic domain walls and increases the magnetic properties [52].
Fig7. X-ray diffraction analysis of Samarium Cobalt 2:17 series after sintering at 1190˚C and
homogenization at 1175˚ C before heat treatment
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Fig8. XRD analysis of Samarium Cobalt 2:17 series after heat treatments at 850˚C for 8 hours and reducing
to 400˚ C for 11 hours. SmCo5 phase has been formed in Sm2Co17 phase
Finally for magnetizing the samples, an external magnetic field which is 2 to 3 times stronger
than the residual field with a magnitude of 2.5 to 3.5 Tesla was applied throughout the ring.
Hystograph model MESSTECHIK BROCKAUS was used to measure the magnetic properties of
sintered samples. Fig 9 is hysteresis curve for a Samarium Cobalt 2:17 series which is first
sintered at 1190˚C and homogenization at 1175˚ C and then heat treated at 850˚C for 8 hours and
finally its temperature is reduced to 400˚ C for 11 hours.
Fig9. Hysteresis curve for a sintered Samarium Cobalt 2:17 series after heat treatments at 850˚C for 8 hours
and reducing to 400˚ C for 11 hours.
4. CONCLUSIONS
The density of Sm2(Co0.67Fe0.23Cu0.07Zr0.03)17 compound varied by controlling the grain size and
the highest density was obtained by using a 3-6 µm green powder. SEM micrographs showed that
the shapes of particles were changed to spherical which was found to be more suitable for
obtaining high density. The highest density achieved by sintering at 1195˚C with a rate of
17˚C/min under the vacuum conditions. Meanwhile, the sample reached to the appropriate density
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by rapid heating at the shortest time. Consequently, a temperature of 1175˚C was found to be the
best homogenizing temperature. Heat treatment process in 850˚C kept for 8 hours to form 1:5
phase at grain boundaries and then reduced to 400˚C in the course of 11 hours was done to
increase the coercivity. Deposits around magnetic domain walls were formed by applying slow
cooling rates.
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AUTHORS
Sirus Javadpour is a Professor at Materials Science and Engineering Department,
Shiraz University, Iran. He received the Ph.D. in Maryland University, USA. His
current research interests include development of fibrous and nanocomposites, bio-
materials, electro-ceramics and the advanced materials.
Alireza Taherizadeh has received his M.Sc. degree in Materials Science and
Engineering (Ceramics and Electroceramics) from Shiraz University, where he
completed his thesis entitled “Manufacturing, investigation and improvement on
magnetic properties of Sm2Co17 and SmCo5 magnets” which was mainly carried
out in the Electroceramics lab at the Department of Materials Engineering, under the
supervision of Prof. Dr. Sirus Javadpour. Since his master's graduation in February
2013, He has been employed as full-time research assistant in Steel Institute of
Isfahan University of Technology, Isfahan, Iran. ‘His field of expertise includes
synthesis and characterization of materials and nanomaterials by novel methods,
ceramics, composites and magnetic materials.
13. International Journal of Electromagnetic ( IJEL ),Vol 2, No 1
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Habibollah Alikhani has received his MSc. Degree degree in Nanotechnology from
Sahand University of Technology. He completed his thesis entitled “The effect of
surface roughness of Inconel 738 superalloy substrate on nano- structured yttria-
stabilized zirconia coating by electrophoretic deposition (EPD)”. He has a good
corporation with Dr Javadpour and his research group. His interesting fields
includes: electromagnetic materials, Zirconia ceramics, nanoparticle and nano-
fabrication.