Hassan Abdollah Pour - Academia.edu (original) (raw)
Papers by Hassan Abdollah Pour
Materials
The aim of the present study is to investigate the role of Ti on corrosion and the wear propertie... more The aim of the present study is to investigate the role of Ti on corrosion and the wear properties of Mg-5Sn-xTi (x = 0, 0.15, 0.75, 1.5 wt.%) alloys. The samples were fabricated by conventional casting followed by hot extrusion, and the studies were examined by means of a pin-on-disc tribometer at various loads of 6, 10, and 20 N with constant sliding velocities of 0.04 m/s at ambient temperature. The corrosion performance, using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), was studied in a basic solution containing 3.5 wt.% NaCl. The observation indicated a drop in the wear rate with an increase in Ti, while the average coefficient of friction was raised in higher Ti contents compared to the base material. The sample with 0.75 wt.% Ti exhibited superior wear properties at 6 and 10 N of normal force, while the sample with 0.15 wt.% Ti presented better wear resistance for 20 N. Electrochemical test observations demonstrated that the Ti deteriorated ...
Physics of Metals and Metallography, 2020
As magnesium and its alloys are almost 35% lighter than aluminum alloys, they are ideal candidate... more As magnesium and its alloys are almost 35% lighter than aluminum alloys, they are ideal candidates for automotive and aerospace industries. In this research, multipass friction stir processing (FSP) was used to produce Mg-based surface nanocomposite with SiO2 particles. Microstructure features such as grain size and particle distribution were investigated. The reactions between magnesium and nanoparticles and the relation between microstructure and hardness, wear resistance, and corrosion behaviour were also studies. The mean grain size of the composite after four passes reduced by 82%, its hardness increased by 29%, and its wear resistance increased more than 34.6% compared with Mg-base alloy. Furthermore, this composite had the best corrosion resistance as a result of fine grain size.
International Journal of Minerals, Metallurgy and Materials, 2020
The main aim of this study was to investigate liquation cracking in the heat-affected zone (HAZ) ... more The main aim of this study was to investigate liquation cracking in the heat-affected zone (HAZ) of the IN939 superalloy upon tungsten inert gas welding. A solid solution and age-hardenable filler metals were further studied. On the pre-weld heat-treated samples, upon solving the secondary γ′ particles in the matrix, primary γ′ particles grew in the base metal to "ogdoadically diced cubes" of about 2 μm in side length. The pre-weld heat treatment reduced the hardness of the base metal to about 310 HV. Microstructural studies using optical and field-emission scanning electron microscopy revealed that the IN939 alloy was susceptible to liquation cracking in the HAZ. The constitutional melting of the secondary, eutectic, and Zr-rich phases promoted the liquation cracking in the HAZ. The microstructure of the weld fusion zones showed the presence of fine spheroidal γ′ particles with a size of about 0.2 μm. The phases increased the hardness of the weld pools after the post-weld heat treatment to about 350 and 380 HV for the Hastelloy X and IN718 filler metals, respectively. Application of a suitable solid solution filler metal could partially reduce the liquation cracking in the HAZ of IN939 alloy.
Environmental Nanotechnology, Monitoring & Management, 2020
Present work introduces the fabrication of antibacterial nanofibers composite of poly(vinyl aceta... more Present work introduces the fabrication of antibacterial nanofibers composite of poly(vinyl acetate) doped with in situsynthesized rice grain-shaped ZnS nanoparticles using electrospinning technique. FE-SEM and TEM analyses revealed that the ZnS nanoparticles were uniformly incorporated inside the polymer nanofibers. The antibacterial activity of as-fabricated nanofibers composite was investigated under indoor light activation towards Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria. Such strategy for immobilizing ceramic nanoparticles inside polymer nanofibers might be helpful to overcome the photocorrosion and recovery problems of ZnS-based materials.
Journal of Materials Engineering and Performance, 2020
Filler metals play an important role in reducing the weld cracking in nickel-based superalloys. I... more Filler metals play an important role in reducing the weld cracking in nickel-based superalloys. In order to improve the welding conditions of IN939 superalloy, a wide range of solid solutions and age-hardenable filler metals were investigated in this study. Five solid solutions (HAYNES 230, IN625, IN617, HAS-TELLOY X, HAYNES 25) and two precipitation-strengthened alloys (IN718, HAYNES C-263) were used as filler metal to weld IN939 superalloy via gas-tungsten-arc welding. Microstructural studies were performed using optical microscopy and field-emission scanning electron microscopy. The results revealed that IN939 alloy is susceptible to liquation cracking in the heat-affected zone. In addition, the primary c¢ particles had grown into ''ogdoadically diced cubes'' of about of 2 lm in side length. The microstructure of the weld pool made with various filler metals was observed to be made up of fine spherical c¢ particles with a diameter of about 0.2 lm. The study of mechanical properties and thermodynamic behavior of the weld showed that the filler metals with lower concentrations of (Al + Ti + Nb + Ta + Mo + W) than the base metal can effectively attenuate the PWHT cracking. We found that optimal IN939 alloy weld performance can be achieved using HAYNES C-263 as filler metal, followed by IN617 and then IN625.
Metallurgical and Materials Transactions A, 2020
Microstructure and phase transformations were investigated in the weld fusion zone (WFZ) of tungs... more Microstructure and phase transformations were investigated in the weld fusion zone (WFZ) of tungsten inert gas (TIG)-welded IN939 nickel-based superalloy with IN718 and IN625 alloys used as filler metal. The optical and field-emission scanning electron microscopy (FESEM) and also energy dispersive spectroscopy (EDS) were utilized for the microstructural study of the WFZ. The microstructural examination showed that the Nb and Ti elements were microsegregated in the inter-dendrite region, causing a significant concentration gradient between the core and the inter-dendrite region within the WFZ. Observations indicated the formation of the (Nb, Ti) C carbide phases in the solidification process. With a thickness of about 0.2 μ m, some plate-like δ phase was observed in the WFZ of both samples upon heat treatment at 750 °C. The results of X-ray diffraction analysis (XRD) confirmed the presence of the δ phase in the WFZ. However, the δ phase disappeared at temperatures beyond 1000 °C. The occurrence of phase transformation during the solidification process was identified by differential thermal analysis (DTA). The WFZ was seen to solidify in the temperature range of 1370°C to 1270°C.
Engineering Research Express, 2019
![Research paper thumbnail of Effect of current density on Ni-Mo electrodeposition using EMIM [Br]](https://attachments.academia-assets.com/118435047/thumbnails/1.jpg)
](Surface Engineering, 2019
This study was conducted to investigate the current density impact on the Ni-Mo electrodeposit an... more This study was conducted to investigate the current density impact on the Ni-Mo electrodeposit and on its catalytic activity of methanol oxidation in an alkaline solution. For this purpose, Ni-Mo coatings with good electrocatalytic properties were achieved by electrodeposition in the modified Watts bath containing 1-ethyl-3-methyl imidazolium bromide (EMIM [Br]) ionic liquid. The results showed that a 1-6 A dm −2 increase in the current density could decline the Mo content in the Ni-Mo/Ni coatings. The XRD patterns demonstrate that an amorphous coating formed with increasing the current density. Moreover, it was found that the catalytic performance of Ni-Mo coatings was significantly enhanced in the presence of methanol. Based on the obtained results, the Ni-Mo coating obtained at the current density of 3.5 A dm −2 and in the presence of EMIM [Br] showed a higher anodic current density, lower onset oxidation potential, and better catalytic performance.
Materials Research Express, 2019
Magnesium-based hybrid composites are light and have better mechanical and tribological propertie... more Magnesium-based hybrid composites are light and have better mechanical and tribological properties than magnesium. In this research, AZ31B–SiO2–graphite hybrid surface composite was produced by multipass friction stir processing (FSP). The effect of FSP passes on microstructure, microhardness, wear resistance, and corrosion resistance of the composite was investigated and compared with friction stir processed (FSPed) AZ31B and as-received AZ31B. The results indicated that after 4 passes, SiO2 and graphite particles properly dispersed in the microstructure and grain growth was restricted due to the pinning effect of these particles; therefore, the mean grain size of the composite decreased by 80% compared with as-received AZ31B. The microhardness of the composite increased about 18% compared with as-received AZ31B and microhardness variation decreased in the stir zone, which indicates more homogeneity in grain size and particle distribution by increasing FSP passes. Furthermore, the investigation of strengthening mechanisms showed that grain size decrease, due to recrystallization and pinning effect of particles, had more influence on increasing composite hardness than dispersion hardening. The wear resistance of the composite which underwent 4 passes was 33% more than as-received AZ31B. It also had the highest corrosion resistance due to more stability of the passive film as a result of fine grain size.
Surface and Coatings Technology, 2018
In this investigation, nickel (Ni)-coated WC-12Co powder was produced using an electroless nickel... more In this investigation, nickel (Ni)-coated WC-12Co powder was produced using an electroless nickel-phosphorus (Ni-P) plating process and then used as a feedstock material for laser cladding of AISI 321 stainless steel substrate. The correlations that exist between key operational parameters of the process (i.e., laser power, scanning speed, powder feeding rate) and geometrical characteristics for single claddings (i.e. height, width, dilution, and wetting angle) were predicted and analyzed by regression analysis method (RA). A processing window for laser cladding of Ni-coated WC-12Co powder on AISI 321 stainless steel was developed based on an empirical-statistical model and the processing window was compared with that for laser cladding of commercial WC-12Co powder without nickel coating. Furthermore, the influence of using Ni-coated WC-12Co powder on the microstructure and microhardness was investigated and compared with those of laser cladded commercial WC-12Co claddings. The results showed that the use of Ni-coated WC-12Co powder could significantly reduce the porosity percentage and lead to high-quality claddings.
Ceramics International, 2018
In this study, the oxidation behavior of WC-12Co and electroless Ni/WC-Co coatings is investigate... more In this study, the oxidation behavior of WC-12Co and electroless Ni/WC-Co coatings is investigated by Thermogravimetric analysis (TGA), X-Ray Diffraction (XRD), and scanning electron microscope (SEM). Time dependence of weight gain showed a linear behavior for WC-Co coating and a parabolic-like behavior for Ni/WC-Co coating. This behavior is related to the reaction-controlled and diffusion-controlled oxidation processes in the WC-Co and Ni/WC-Co coatings, respectively. Oxidation resistance of coatings was determined by phase composition and formation mechanism of the protective oxide layer. The results demonstrated that the use of Ni/WC-Co powder could reduce significantly the porosity and cracks and lead to a compact and protective (Ni, Co)WO 4 layer. The apparent activation energy was measured to be about 98.3 and 229.4kJ/mol for WC-Co and Ni/WC-Co coatings, respectively.
Materials Research Express, 2019
Journal of Materials Research and Technology, 2019
High-purity porous nanostructured silicon particles were successfully produced from quartzite roc... more High-purity porous nanostructured silicon particles were successfully produced from quartzite rock via the multi-step processing route including primary acid leaching of crashed quartzite feedstock, wet blending of quartzite and magnesium powder, reduction, and final multi-stage hydrometallurgical purification of the products. Laboratory-grade silica was also treated for comparison. The effect of silica purity, reactants' molar ratios (Mg:SiO 2), and hydrometallurgical refining on reaction products were investigated and discussed through the results of X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) equipped with energy dispersive spectroscopy (EDS) and inductively coupled plasma-mass spectrometry (ICP-MS). The results indicated that the combination of primary acid treatment, combustion synthesis in controlled atmosphere, and final special acid leaching process is an efficient route for the production of porous nanostructured elemental silicon particles with a uniform structure that can be used in several applications in the energy sector with or without further processing.
International Journal of Refractory Metals and Hard Materials, 2019
This research investigates the wear performance of WC-12Co and electroless Ni/WC-Co deposits at h... more This research investigates the wear performance of WC-12Co and electroless Ni/WC-Co deposits at high temperature. Dry sliding wear experiments were carried out for coated and uncoated steel substrate against alumina pin. The microstructure and wear performance of laser-cladded WC-Co and Ni/WC-Co were characterized by X-ray diffraction pattern (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) techniques. The mass reduction, friction coefficient, and wear rate of Ni/WC-Co deposits were measured and found to be significantly lower than WC-Co coatings. Due to the presence of Ni coating around the particle of the Ni/WC-Co coating, it showed a lower microhardness, more homogeneous microstructure, and a higher wear performance compared to WC-Co coating. The results of this paper indicated that the dominant mechanisms in wearing distance were adhesive, abrasive, and pulling out from the particles.
Journal of Magnetism and Magnetic Materials, 2018
Nanocrystalline CoZr x Fe 2-x O 4 (0 ≤ x ≤ 0.3 in a step of 0.05) powders were synthesized by Pec... more Nanocrystalline CoZr x Fe 2-x O 4 (0 ≤ x ≤ 0.3 in a step of 0.05) powders were synthesized by Pechini sol-gel method. The dry gel was grinded and calcined at 700 °C in a static air atmosphere for 1 h. Some tests such as thermo gravimetric analysis (TGA) combined with differential analysis (DTA), fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and vibrating sample magnetometer (VSM) were carried out to investigate the thermal behaviour, structural bonds identification, crystallographic properties, morphology and magnetic properties of the obtained powders. X-ray diffraction revealed a single-phase cubic spinel structure for all samples, where the crystallite size decreases; the lattice parameter simultaneously increases with substitution of Zr. The results of FE-SEM showed that the particle size is in the 20-70 nm range. The magnetic properties such as saturation magnetization (Ms), remanent magnetization (Mr) and coercivity (Hc) were measured from the hysteresis loops. The greatest amount of saturation magnetization for CoZr 0.05 Fe 1.95 O 4 sample was 67.9 emu.g-1 .
Optics & Laser Technology, 2017
In this article, Ti-6Al-4V powder alloy was directly deposited on Ti-6Al-4V substrate using laser... more In this article, Ti-6Al-4V powder alloy was directly deposited on Ti-6Al-4V substrate using laser cladding process. In this process, some key parameters such as laser power (P), laser scanning rate (V) and powder feeding rate (F) play important roles. Using linear regression analysis, this paper develops the empiricalstatistical relation between these key parameters and geometrical characteristics of single clad tracks (i.e. clad height, clad width, penetration depth, wetting angle, and dilution) as a combined parameter (P a V b F c). The results indicated that the clad width linearly depended on PV À1/3 and powder feeding rate had no effect on it. The dilution controlled by a combined parameter as VF À1/2 and laser power was a dispensable factor. However, laser power was the dominant factor for the clad height, penetration depth, and wetting angle so that they were proportional to PV À1 F 1/4 , PVF À1/8 , and P 3/4 V À1 F À1/4 , respectively. Based on the results of correlation coefficient (R > 0.9) and analysis of residuals, it was confirmed that these empirical-statistical relations were in good agreement with the measured values of single clad tracks. Finally, these relations led to the design of a processing map that can predict the geometrical characteristics of the single clad tracks based on the key parameters.
Journal of Alloys and Compounds, 2017
In this study, the effect of accumulative roll bonding (ARB) process on the microstructure, defor... more In this study, the effect of accumulative roll bonding (ARB) process on the microstructure, deformation texture and mechanical properties of AA2024 strip was investigated. Microstructural observations were done by electron backscattering diffraction (EBSD) technique and scanning electron microscopy (SEM). Also, mechanical properties were performed by uniaxial tensile and microhardness tests. It was observed that accumulative roll bonding is a promising process for production of nano/ultrafine grained (NG/UFG) 2024 aluminum alloy after seventh ARB cycles, reaching grain sizes of smaller than 120 nm. The fraction of high angle grain boundaries and mean misorientation is represented increased by increasing the strain during the ARB process and reached to a saturated value of 64% and 25.37°, respectively. Deformation texture evolution demonstrated that the formation of nano shear bands at the final ARB cycle was facilitated by the formation of Brass {011}<211> and Goss {011}<100> components. By increasing the number of ARB cycles, the yield strength, tensile strength and microhardness of the ARB processed sample improved and reached to 345 MPa, 450 MPa and 141 HV after 7 cycles, respectively, which were 2.65, 2.40 and 2.23 times higher than obtained values for initial materials, i.e. 130 MPa, 188 MPa and 63.5 HV. After the tensile test, debonding can be observed especially in the interface formed in the last cycle. Observations revealed that the failure mode in the accumulatively roll bonded AA2024 strip was a shear ductile rupture with elongated shallow shear dimples.
Metal Science and Heat Treatment, 2014
Materials
The aim of the present study is to investigate the role of Ti on corrosion and the wear propertie... more The aim of the present study is to investigate the role of Ti on corrosion and the wear properties of Mg-5Sn-xTi (x = 0, 0.15, 0.75, 1.5 wt.%) alloys. The samples were fabricated by conventional casting followed by hot extrusion, and the studies were examined by means of a pin-on-disc tribometer at various loads of 6, 10, and 20 N with constant sliding velocities of 0.04 m/s at ambient temperature. The corrosion performance, using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), was studied in a basic solution containing 3.5 wt.% NaCl. The observation indicated a drop in the wear rate with an increase in Ti, while the average coefficient of friction was raised in higher Ti contents compared to the base material. The sample with 0.75 wt.% Ti exhibited superior wear properties at 6 and 10 N of normal force, while the sample with 0.15 wt.% Ti presented better wear resistance for 20 N. Electrochemical test observations demonstrated that the Ti deteriorated ...
Physics of Metals and Metallography, 2020
As magnesium and its alloys are almost 35% lighter than aluminum alloys, they are ideal candidate... more As magnesium and its alloys are almost 35% lighter than aluminum alloys, they are ideal candidates for automotive and aerospace industries. In this research, multipass friction stir processing (FSP) was used to produce Mg-based surface nanocomposite with SiO2 particles. Microstructure features such as grain size and particle distribution were investigated. The reactions between magnesium and nanoparticles and the relation between microstructure and hardness, wear resistance, and corrosion behaviour were also studies. The mean grain size of the composite after four passes reduced by 82%, its hardness increased by 29%, and its wear resistance increased more than 34.6% compared with Mg-base alloy. Furthermore, this composite had the best corrosion resistance as a result of fine grain size.
International Journal of Minerals, Metallurgy and Materials, 2020
The main aim of this study was to investigate liquation cracking in the heat-affected zone (HAZ) ... more The main aim of this study was to investigate liquation cracking in the heat-affected zone (HAZ) of the IN939 superalloy upon tungsten inert gas welding. A solid solution and age-hardenable filler metals were further studied. On the pre-weld heat-treated samples, upon solving the secondary γ′ particles in the matrix, primary γ′ particles grew in the base metal to "ogdoadically diced cubes" of about 2 μm in side length. The pre-weld heat treatment reduced the hardness of the base metal to about 310 HV. Microstructural studies using optical and field-emission scanning electron microscopy revealed that the IN939 alloy was susceptible to liquation cracking in the HAZ. The constitutional melting of the secondary, eutectic, and Zr-rich phases promoted the liquation cracking in the HAZ. The microstructure of the weld fusion zones showed the presence of fine spheroidal γ′ particles with a size of about 0.2 μm. The phases increased the hardness of the weld pools after the post-weld heat treatment to about 350 and 380 HV for the Hastelloy X and IN718 filler metals, respectively. Application of a suitable solid solution filler metal could partially reduce the liquation cracking in the HAZ of IN939 alloy.
Environmental Nanotechnology, Monitoring & Management, 2020
Present work introduces the fabrication of antibacterial nanofibers composite of poly(vinyl aceta... more Present work introduces the fabrication of antibacterial nanofibers composite of poly(vinyl acetate) doped with in situsynthesized rice grain-shaped ZnS nanoparticles using electrospinning technique. FE-SEM and TEM analyses revealed that the ZnS nanoparticles were uniformly incorporated inside the polymer nanofibers. The antibacterial activity of as-fabricated nanofibers composite was investigated under indoor light activation towards Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria. Such strategy for immobilizing ceramic nanoparticles inside polymer nanofibers might be helpful to overcome the photocorrosion and recovery problems of ZnS-based materials.
Journal of Materials Engineering and Performance, 2020
Filler metals play an important role in reducing the weld cracking in nickel-based superalloys. I... more Filler metals play an important role in reducing the weld cracking in nickel-based superalloys. In order to improve the welding conditions of IN939 superalloy, a wide range of solid solutions and age-hardenable filler metals were investigated in this study. Five solid solutions (HAYNES 230, IN625, IN617, HAS-TELLOY X, HAYNES 25) and two precipitation-strengthened alloys (IN718, HAYNES C-263) were used as filler metal to weld IN939 superalloy via gas-tungsten-arc welding. Microstructural studies were performed using optical microscopy and field-emission scanning electron microscopy. The results revealed that IN939 alloy is susceptible to liquation cracking in the heat-affected zone. In addition, the primary c¢ particles had grown into ''ogdoadically diced cubes'' of about of 2 lm in side length. The microstructure of the weld pool made with various filler metals was observed to be made up of fine spherical c¢ particles with a diameter of about 0.2 lm. The study of mechanical properties and thermodynamic behavior of the weld showed that the filler metals with lower concentrations of (Al + Ti + Nb + Ta + Mo + W) than the base metal can effectively attenuate the PWHT cracking. We found that optimal IN939 alloy weld performance can be achieved using HAYNES C-263 as filler metal, followed by IN617 and then IN625.
Metallurgical and Materials Transactions A, 2020
Microstructure and phase transformations were investigated in the weld fusion zone (WFZ) of tungs... more Microstructure and phase transformations were investigated in the weld fusion zone (WFZ) of tungsten inert gas (TIG)-welded IN939 nickel-based superalloy with IN718 and IN625 alloys used as filler metal. The optical and field-emission scanning electron microscopy (FESEM) and also energy dispersive spectroscopy (EDS) were utilized for the microstructural study of the WFZ. The microstructural examination showed that the Nb and Ti elements were microsegregated in the inter-dendrite region, causing a significant concentration gradient between the core and the inter-dendrite region within the WFZ. Observations indicated the formation of the (Nb, Ti) C carbide phases in the solidification process. With a thickness of about 0.2 μ m, some plate-like δ phase was observed in the WFZ of both samples upon heat treatment at 750 °C. The results of X-ray diffraction analysis (XRD) confirmed the presence of the δ phase in the WFZ. However, the δ phase disappeared at temperatures beyond 1000 °C. The occurrence of phase transformation during the solidification process was identified by differential thermal analysis (DTA). The WFZ was seen to solidify in the temperature range of 1370°C to 1270°C.
Engineering Research Express, 2019
Surface Engineering, 2019
This study was conducted to investigate the current density impact on the Ni-Mo electrodeposit an... more This study was conducted to investigate the current density impact on the Ni-Mo electrodeposit and on its catalytic activity of methanol oxidation in an alkaline solution. For this purpose, Ni-Mo coatings with good electrocatalytic properties were achieved by electrodeposition in the modified Watts bath containing 1-ethyl-3-methyl imidazolium bromide (EMIM [Br]) ionic liquid. The results showed that a 1-6 A dm −2 increase in the current density could decline the Mo content in the Ni-Mo/Ni coatings. The XRD patterns demonstrate that an amorphous coating formed with increasing the current density. Moreover, it was found that the catalytic performance of Ni-Mo coatings was significantly enhanced in the presence of methanol. Based on the obtained results, the Ni-Mo coating obtained at the current density of 3.5 A dm −2 and in the presence of EMIM [Br] showed a higher anodic current density, lower onset oxidation potential, and better catalytic performance.
Materials Research Express, 2019
Magnesium-based hybrid composites are light and have better mechanical and tribological propertie... more Magnesium-based hybrid composites are light and have better mechanical and tribological properties than magnesium. In this research, AZ31B–SiO2–graphite hybrid surface composite was produced by multipass friction stir processing (FSP). The effect of FSP passes on microstructure, microhardness, wear resistance, and corrosion resistance of the composite was investigated and compared with friction stir processed (FSPed) AZ31B and as-received AZ31B. The results indicated that after 4 passes, SiO2 and graphite particles properly dispersed in the microstructure and grain growth was restricted due to the pinning effect of these particles; therefore, the mean grain size of the composite decreased by 80% compared with as-received AZ31B. The microhardness of the composite increased about 18% compared with as-received AZ31B and microhardness variation decreased in the stir zone, which indicates more homogeneity in grain size and particle distribution by increasing FSP passes. Furthermore, the investigation of strengthening mechanisms showed that grain size decrease, due to recrystallization and pinning effect of particles, had more influence on increasing composite hardness than dispersion hardening. The wear resistance of the composite which underwent 4 passes was 33% more than as-received AZ31B. It also had the highest corrosion resistance due to more stability of the passive film as a result of fine grain size.
Surface and Coatings Technology, 2018
In this investigation, nickel (Ni)-coated WC-12Co powder was produced using an electroless nickel... more In this investigation, nickel (Ni)-coated WC-12Co powder was produced using an electroless nickel-phosphorus (Ni-P) plating process and then used as a feedstock material for laser cladding of AISI 321 stainless steel substrate. The correlations that exist between key operational parameters of the process (i.e., laser power, scanning speed, powder feeding rate) and geometrical characteristics for single claddings (i.e. height, width, dilution, and wetting angle) were predicted and analyzed by regression analysis method (RA). A processing window for laser cladding of Ni-coated WC-12Co powder on AISI 321 stainless steel was developed based on an empirical-statistical model and the processing window was compared with that for laser cladding of commercial WC-12Co powder without nickel coating. Furthermore, the influence of using Ni-coated WC-12Co powder on the microstructure and microhardness was investigated and compared with those of laser cladded commercial WC-12Co claddings. The results showed that the use of Ni-coated WC-12Co powder could significantly reduce the porosity percentage and lead to high-quality claddings.
Ceramics International, 2018
In this study, the oxidation behavior of WC-12Co and electroless Ni/WC-Co coatings is investigate... more In this study, the oxidation behavior of WC-12Co and electroless Ni/WC-Co coatings is investigated by Thermogravimetric analysis (TGA), X-Ray Diffraction (XRD), and scanning electron microscope (SEM). Time dependence of weight gain showed a linear behavior for WC-Co coating and a parabolic-like behavior for Ni/WC-Co coating. This behavior is related to the reaction-controlled and diffusion-controlled oxidation processes in the WC-Co and Ni/WC-Co coatings, respectively. Oxidation resistance of coatings was determined by phase composition and formation mechanism of the protective oxide layer. The results demonstrated that the use of Ni/WC-Co powder could reduce significantly the porosity and cracks and lead to a compact and protective (Ni, Co)WO 4 layer. The apparent activation energy was measured to be about 98.3 and 229.4kJ/mol for WC-Co and Ni/WC-Co coatings, respectively.
Materials Research Express, 2019
Journal of Materials Research and Technology, 2019
High-purity porous nanostructured silicon particles were successfully produced from quartzite roc... more High-purity porous nanostructured silicon particles were successfully produced from quartzite rock via the multi-step processing route including primary acid leaching of crashed quartzite feedstock, wet blending of quartzite and magnesium powder, reduction, and final multi-stage hydrometallurgical purification of the products. Laboratory-grade silica was also treated for comparison. The effect of silica purity, reactants' molar ratios (Mg:SiO 2), and hydrometallurgical refining on reaction products were investigated and discussed through the results of X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) equipped with energy dispersive spectroscopy (EDS) and inductively coupled plasma-mass spectrometry (ICP-MS). The results indicated that the combination of primary acid treatment, combustion synthesis in controlled atmosphere, and final special acid leaching process is an efficient route for the production of porous nanostructured elemental silicon particles with a uniform structure that can be used in several applications in the energy sector with or without further processing.
International Journal of Refractory Metals and Hard Materials, 2019
This research investigates the wear performance of WC-12Co and electroless Ni/WC-Co deposits at h... more This research investigates the wear performance of WC-12Co and electroless Ni/WC-Co deposits at high temperature. Dry sliding wear experiments were carried out for coated and uncoated steel substrate against alumina pin. The microstructure and wear performance of laser-cladded WC-Co and Ni/WC-Co were characterized by X-ray diffraction pattern (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) techniques. The mass reduction, friction coefficient, and wear rate of Ni/WC-Co deposits were measured and found to be significantly lower than WC-Co coatings. Due to the presence of Ni coating around the particle of the Ni/WC-Co coating, it showed a lower microhardness, more homogeneous microstructure, and a higher wear performance compared to WC-Co coating. The results of this paper indicated that the dominant mechanisms in wearing distance were adhesive, abrasive, and pulling out from the particles.
Journal of Magnetism and Magnetic Materials, 2018
Nanocrystalline CoZr x Fe 2-x O 4 (0 ≤ x ≤ 0.3 in a step of 0.05) powders were synthesized by Pec... more Nanocrystalline CoZr x Fe 2-x O 4 (0 ≤ x ≤ 0.3 in a step of 0.05) powders were synthesized by Pechini sol-gel method. The dry gel was grinded and calcined at 700 °C in a static air atmosphere for 1 h. Some tests such as thermo gravimetric analysis (TGA) combined with differential analysis (DTA), fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and vibrating sample magnetometer (VSM) were carried out to investigate the thermal behaviour, structural bonds identification, crystallographic properties, morphology and magnetic properties of the obtained powders. X-ray diffraction revealed a single-phase cubic spinel structure for all samples, where the crystallite size decreases; the lattice parameter simultaneously increases with substitution of Zr. The results of FE-SEM showed that the particle size is in the 20-70 nm range. The magnetic properties such as saturation magnetization (Ms), remanent magnetization (Mr) and coercivity (Hc) were measured from the hysteresis loops. The greatest amount of saturation magnetization for CoZr 0.05 Fe 1.95 O 4 sample was 67.9 emu.g-1 .
Optics & Laser Technology, 2017
In this article, Ti-6Al-4V powder alloy was directly deposited on Ti-6Al-4V substrate using laser... more In this article, Ti-6Al-4V powder alloy was directly deposited on Ti-6Al-4V substrate using laser cladding process. In this process, some key parameters such as laser power (P), laser scanning rate (V) and powder feeding rate (F) play important roles. Using linear regression analysis, this paper develops the empiricalstatistical relation between these key parameters and geometrical characteristics of single clad tracks (i.e. clad height, clad width, penetration depth, wetting angle, and dilution) as a combined parameter (P a V b F c). The results indicated that the clad width linearly depended on PV À1/3 and powder feeding rate had no effect on it. The dilution controlled by a combined parameter as VF À1/2 and laser power was a dispensable factor. However, laser power was the dominant factor for the clad height, penetration depth, and wetting angle so that they were proportional to PV À1 F 1/4 , PVF À1/8 , and P 3/4 V À1 F À1/4 , respectively. Based on the results of correlation coefficient (R > 0.9) and analysis of residuals, it was confirmed that these empirical-statistical relations were in good agreement with the measured values of single clad tracks. Finally, these relations led to the design of a processing map that can predict the geometrical characteristics of the single clad tracks based on the key parameters.
Journal of Alloys and Compounds, 2017
In this study, the effect of accumulative roll bonding (ARB) process on the microstructure, defor... more In this study, the effect of accumulative roll bonding (ARB) process on the microstructure, deformation texture and mechanical properties of AA2024 strip was investigated. Microstructural observations were done by electron backscattering diffraction (EBSD) technique and scanning electron microscopy (SEM). Also, mechanical properties were performed by uniaxial tensile and microhardness tests. It was observed that accumulative roll bonding is a promising process for production of nano/ultrafine grained (NG/UFG) 2024 aluminum alloy after seventh ARB cycles, reaching grain sizes of smaller than 120 nm. The fraction of high angle grain boundaries and mean misorientation is represented increased by increasing the strain during the ARB process and reached to a saturated value of 64% and 25.37°, respectively. Deformation texture evolution demonstrated that the formation of nano shear bands at the final ARB cycle was facilitated by the formation of Brass {011}<211> and Goss {011}<100> components. By increasing the number of ARB cycles, the yield strength, tensile strength and microhardness of the ARB processed sample improved and reached to 345 MPa, 450 MPa and 141 HV after 7 cycles, respectively, which were 2.65, 2.40 and 2.23 times higher than obtained values for initial materials, i.e. 130 MPa, 188 MPa and 63.5 HV. After the tensile test, debonding can be observed especially in the interface formed in the last cycle. Observations revealed that the failure mode in the accumulatively roll bonded AA2024 strip was a shear ductile rupture with elongated shallow shear dimples.
Metal Science and Heat Treatment, 2014