Nader Parvin | AmirKabir University Of Technology (original) (raw)

Papers by Nader Parvin

Journal of Physics D, May 13, 2021

These days, magnetic nanoparticles (MNPs), especially cobalt ferrite MNPs, have attracted the att... more These days, magnetic nanoparticles (MNPs), especially cobalt ferrite MNPs, have attracted the attention of many scientists in many applications, e.g. cancer treatment, due to their good magnetic properties. In this study, firstly the Ni x Co1−x Fe2O4 MNPs (x = 0, 0.25, 0.5, and 0.75) were prepared through the sol–gel technique. The resulting particles were then coated with polyethylene glycol (PEG) polymer to obtain a core/shell structure. The x-ray diffraction and Fourier-transform infrared spectroscopy results illustrated that CoFe2O4 MNPs were successfully synthesized. Vibrating-sample magnetometer and (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bro-mide) assay results illustrated that the Ni0.5Co0.5Fe2O4 sample had the best saturation magnetization (71.68 emu g−1) and coercivity (∼500 Oe) values. Subsequently, the appropriate amount of PEG was found to be 15% wt/vol. The toxicity test showed that a concentration of 100 μg ml−1 of particles kept 96% of the cells alive. The particle size of the core/shelled MNPs was obtained to be ∼25 nm via a transmission electron microscopy image. Finally, it was observed that the Ni0.5Co0.5Fe2O4 sample coated with 15% wt/vol. PEG can be potentially used for hyperthermia.

Materials & Design, 2009

Severe deformation processing is an emerging technique, for the production of submicron grain str... more Severe deformation processing is an emerging technique, for the production of submicron grain structures in metallic material, which involves plastic deformation to ultra-high strains. An ultra-fine grained (UFG) material was prepared from an IF steel sheet using Accumulative Roll Bonding (ARB) process. After initial preparing to achieve good sheet bonding, ten cycles of ARB at 500 °C were successfully performed. Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM) were used for the characterization of subgrain and grain structures of ARB processed samples. The mechanical attributes after rolling and cooling were examined. Also, the fracture surfaces were studied by Scanning Electron Microscopy (SEM). It was concluded that metal’s tensile strengths increased by 334% while the ductility dropped from a pre-rolled value of 50.5% to 2.6%. The rolling process was stopped in cycle 10, when cracking of the edges became pronounced.

In this research, infiltration behavior of W-Ag composite compacts with Nickel and Cobalt as addi... more In this research, infiltration behavior of W-Ag composite compacts with Nickel and Cobalt as additives has been investigated. Nickel and Cobalt were added to Tungsten powder by two distinct methods: mixing elementally and reduction of salt solution. The coated Tungsten powders were compacted under controlled pressures to make porous skeleton with 32-37 vol. % porosity. Infiltration process was carried out at 1100 ̊C under a reducing atmosphere for 1h. The effect of additives on infiltration of Ag and density were evaluated by SEM and Archimedes methods. Properties of the specimens were compared following two distinct processes namely: I) sintering simultaneously with infiltration process and II) sintering prior to infiltration (pre-sintering process). It was found that specimens which were pre-sintered and then infiltrated with molten silver represent higher hardness and finer microstructure than the specimens infiltrated simultaneously with sintering.

The fundamental objective of this work is an observation the influence of accumulative roll bondi... more The fundamental objective of this work is an observation the influence of accumulative roll bonding (ARB) on grain refinement and their induced mechanical properties of interstitial free steel strips. To that end, a number of ARB was carried out at 500˚C, with 50% reduction in area of each rolling pass. The process was stopped when cracking of the edges became pronounced. The results indicate that both the ultimate grain size achieved, as well as the degree of bonding, depend on the number of ARB pass and total reduction of area. The average grain size measured using SEM and optical microscopy was about 225nm. The mechanical properties after rolling and cooling were obtained. Hardness of the samples was obtained using micro hardness tests. For all samples the hardness distribution along the thickness was directly proportional to the mean grain size. Furthermore, the effect of wire brushing on samples was investigated showing an increase of 7 HV induced by wire brushing.

Journal of Alloys and Compounds, 2010

ABSTRACT Nanostructured oxide dispersion strengthened (ODS) Fe-based alloys manufactured by mecha... more ABSTRACT Nanostructured oxide dispersion strengthened (ODS) Fe-based alloys manufactured by mechanical alloying (MA) are generally considered to be promising candidate materials for high-temperature applications up to at least 1100°C because of their excellent creep strength and good oxidation resistance. However, a key issue with these alloys is the difficulty in using fusion welding techniques to join components due to oxide particle agglomeration and loss in the weld zone and the disruption and discontinuity in the grain structure introduced at the bond. In this study, the evolution of microstructure has been comprehensively studied in friction stir welds in a ferritic ODS alloy. Initially, electron backscattering diffraction (EBSD) was used to analyze the grain orientation, the grain boundary geometries and recrystallization behaviour. It suggested that deformation heterogeneities were introduced during the friction stirring process which facilitated the onset of recrystallization. Transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) were used to observe the effects of the friction stir welding (FSW) process on the grain structure and the distribution of Y2O3 and other particles in the metal substrates in the FSW and adjacent regions, after the alloys had been recrystallized at temperatures up to 1380°C for 1h in air. The results show that fine-equiaxed grains and a uniform distribution of oxide particles were present in the friction stirred region but that the grain boundaries in the parent metal were pinned by particles. Friction stirring appeared to release these boundaries and allowed secondary recrystallization to occur after further heat treatment. The FSW process appears to be a promising technique for joining ferritic ODS alloys in the form of sheet and tube.

Materials Science Forum, 2006

Investigations of the behavior of ultrafine-grained (UFG) materials manufactured by severe plasti... more Investigations of the behavior of ultrafine-grained (UFG) materials manufactured by severe plastic deformation (SPD) have been greatly motivated by the expectations that they may have unique properties as well as by the desire to understand the fundamental mechanisms underlying the specific properties associated with extreme grain refinement. Although the concurrent improvement of both strength and ductility is possible via SPD, the most commonly observed high strength of UFG materials is paired with a very limited uniform elongation. Based on the dislocation kinetics and its relation with the Consid ere instability, an attempt is made to provide a unified view for the hardening behaviour and early macroscopic strain localization.

Journal of Materials Science

The cold sintering process was applied as a suitable method to produce high relative density (&am... more The cold sintering process was applied as a suitable method to produce high relative density (> 90%) ZnO/MoS2 nanocomposite. The cold sintering process was done at 170 °C, 480 MPa for 45 min to fabricate ZnO/MoS2 nanocomposite in a bulk form containing 1–5% MoS2. In addition to examining the effective parameters of the process, the proper solvents in cold sintering of ZnO/MoS2 nanocomposite were investigated. The XRD, FTIR, and RAMAN results affirmed the removal of added solvent and the absence of any secondary phase or unknown component in the cold-sintered ZnO/MoS2 nanocomposite. The SEM and EDX results illustrated that to improve the MoS2 nanoparticle homogeneous distribution through the ZnO powders, a new three-component solvent (acetic acid-DMSO-water) with enhanced viscosity should be exerted. Increasing MoS2 nanoparticles resulted in a slight reduction in the final density of the nanocomposite as 5% MoS2 decreased the relative density from 95.2 to 90.9%. The TGA/DTA curves proved that the thermal stability of the fabricated nanocomposite was up to 450 °C. Alongside the bulk form of the produced nanocomposite, UV–visible investigations illustrated that the MoS2 nanoparticles enhanced the ZnO substrate's visible light absorption, indicating the potential of the cold-sintered ZnO/MoS2 nanocomposite for development in optical applications.

The ZnO/MoS2 nanocomposites were fabricated by a cold sintering process using a three-component s... more The ZnO/MoS2 nanocomposites were fabricated by a cold sintering process using a three-component solvent to produce high-density bulks (>90%). The effect of 1-5% MoS2 nanoparticles on mechanical properties (strength, elastic modulus, fracture toughness, and hardness) and tribological properties (mass loss, friction of coefficient, and wear rate) of the material was investigated. The 1% MoS2 improved the hardness and fracture toughness of nanocomposite by 2.22 GPa and 2.33 MPa√m, respectively, with a 23% enhancement in the wear resistance by 1.55×10 −5 mm 3 /N.m. Further increase in the nanoparticle's value caused a reduction in mechanical properties; however, the nanocomposite's friction coefficient was proportionally reduced with MoS2 enhancement up to 0.26. The MoS2 nanoparticles, despite the formation of smoother surfaces, have progressed the adhesive mechanism.

Materials Chemistry and Physics

Synthesis and Sintering

A novel Mg-0.7Ca alloy was prepared by the mechanical alloying (MA) process. Different variables ... more A novel Mg-0.7Ca alloy was prepared by the mechanical alloying (MA) process. Different variables were examined in order to obtain the optimum sample with the best milling behavior and potential sinterability. The structural studies were carried out using X-ray Diffractometer (XRD) and scanning electron microscopy (SEM). Crystallite size and lattice strain of the milled samples were examined by Scherrer and Williamson-Hall methods in order to finalize the investigation. The optimum milling time was found to be 60 minutes. In addition, a starch-containing sample with a fraction of 2.5 weight percent seemed to have the best microstructural properties, based on SEM observations and crystallite size assessments. Due discussions about the effective phenomena during the mechanical alloying were also included.

Proceedings of the Institution of Mechanical Engineers. Part L. Journal of Materials: Design and Applications, 2017

Journal of Physics D, May 13, 2021

These days, magnetic nanoparticles (MNPs), especially cobalt ferrite MNPs, have attracted the att... more These days, magnetic nanoparticles (MNPs), especially cobalt ferrite MNPs, have attracted the attention of many scientists in many applications, e.g. cancer treatment, due to their good magnetic properties. In this study, firstly the Ni x Co1−x Fe2O4 MNPs (x = 0, 0.25, 0.5, and 0.75) were prepared through the sol–gel technique. The resulting particles were then coated with polyethylene glycol (PEG) polymer to obtain a core/shell structure. The x-ray diffraction and Fourier-transform infrared spectroscopy results illustrated that CoFe2O4 MNPs were successfully synthesized. Vibrating-sample magnetometer and (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bro-mide) assay results illustrated that the Ni0.5Co0.5Fe2O4 sample had the best saturation magnetization (71.68 emu g−1) and coercivity (∼500 Oe) values. Subsequently, the appropriate amount of PEG was found to be 15% wt/vol. The toxicity test showed that a concentration of 100 μg ml−1 of particles kept 96% of the cells alive. The particle size of the core/shelled MNPs was obtained to be ∼25 nm via a transmission electron microscopy image. Finally, it was observed that the Ni0.5Co0.5Fe2O4 sample coated with 15% wt/vol. PEG can be potentially used for hyperthermia.

Materials & Design, 2009

Severe deformation processing is an emerging technique, for the production of submicron grain str... more Severe deformation processing is an emerging technique, for the production of submicron grain structures in metallic material, which involves plastic deformation to ultra-high strains. An ultra-fine grained (UFG) material was prepared from an IF steel sheet using Accumulative Roll Bonding (ARB) process. After initial preparing to achieve good sheet bonding, ten cycles of ARB at 500 °C were successfully performed. Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM) were used for the characterization of subgrain and grain structures of ARB processed samples. The mechanical attributes after rolling and cooling were examined. Also, the fracture surfaces were studied by Scanning Electron Microscopy (SEM). It was concluded that metal’s tensile strengths increased by 334% while the ductility dropped from a pre-rolled value of 50.5% to 2.6%. The rolling process was stopped in cycle 10, when cracking of the edges became pronounced.

In this research, infiltration behavior of W-Ag composite compacts with Nickel and Cobalt as addi... more In this research, infiltration behavior of W-Ag composite compacts with Nickel and Cobalt as additives has been investigated. Nickel and Cobalt were added to Tungsten powder by two distinct methods: mixing elementally and reduction of salt solution. The coated Tungsten powders were compacted under controlled pressures to make porous skeleton with 32-37 vol. % porosity. Infiltration process was carried out at 1100 ̊C under a reducing atmosphere for 1h. The effect of additives on infiltration of Ag and density were evaluated by SEM and Archimedes methods. Properties of the specimens were compared following two distinct processes namely: I) sintering simultaneously with infiltration process and II) sintering prior to infiltration (pre-sintering process). It was found that specimens which were pre-sintered and then infiltrated with molten silver represent higher hardness and finer microstructure than the specimens infiltrated simultaneously with sintering.

The fundamental objective of this work is an observation the influence of accumulative roll bondi... more The fundamental objective of this work is an observation the influence of accumulative roll bonding (ARB) on grain refinement and their induced mechanical properties of interstitial free steel strips. To that end, a number of ARB was carried out at 500˚C, with 50% reduction in area of each rolling pass. The process was stopped when cracking of the edges became pronounced. The results indicate that both the ultimate grain size achieved, as well as the degree of bonding, depend on the number of ARB pass and total reduction of area. The average grain size measured using SEM and optical microscopy was about 225nm. The mechanical properties after rolling and cooling were obtained. Hardness of the samples was obtained using micro hardness tests. For all samples the hardness distribution along the thickness was directly proportional to the mean grain size. Furthermore, the effect of wire brushing on samples was investigated showing an increase of 7 HV induced by wire brushing.

Journal of Alloys and Compounds, 2010

ABSTRACT Nanostructured oxide dispersion strengthened (ODS) Fe-based alloys manufactured by mecha... more ABSTRACT Nanostructured oxide dispersion strengthened (ODS) Fe-based alloys manufactured by mechanical alloying (MA) are generally considered to be promising candidate materials for high-temperature applications up to at least 1100°C because of their excellent creep strength and good oxidation resistance. However, a key issue with these alloys is the difficulty in using fusion welding techniques to join components due to oxide particle agglomeration and loss in the weld zone and the disruption and discontinuity in the grain structure introduced at the bond. In this study, the evolution of microstructure has been comprehensively studied in friction stir welds in a ferritic ODS alloy. Initially, electron backscattering diffraction (EBSD) was used to analyze the grain orientation, the grain boundary geometries and recrystallization behaviour. It suggested that deformation heterogeneities were introduced during the friction stirring process which facilitated the onset of recrystallization. Transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) were used to observe the effects of the friction stir welding (FSW) process on the grain structure and the distribution of Y2O3 and other particles in the metal substrates in the FSW and adjacent regions, after the alloys had been recrystallized at temperatures up to 1380°C for 1h in air. The results show that fine-equiaxed grains and a uniform distribution of oxide particles were present in the friction stirred region but that the grain boundaries in the parent metal were pinned by particles. Friction stirring appeared to release these boundaries and allowed secondary recrystallization to occur after further heat treatment. The FSW process appears to be a promising technique for joining ferritic ODS alloys in the form of sheet and tube.

Materials Science Forum, 2006

Investigations of the behavior of ultrafine-grained (UFG) materials manufactured by severe plasti... more Investigations of the behavior of ultrafine-grained (UFG) materials manufactured by severe plastic deformation (SPD) have been greatly motivated by the expectations that they may have unique properties as well as by the desire to understand the fundamental mechanisms underlying the specific properties associated with extreme grain refinement. Although the concurrent improvement of both strength and ductility is possible via SPD, the most commonly observed high strength of UFG materials is paired with a very limited uniform elongation. Based on the dislocation kinetics and its relation with the Consid ere instability, an attempt is made to provide a unified view for the hardening behaviour and early macroscopic strain localization.

Journal of Materials Science

The cold sintering process was applied as a suitable method to produce high relative density (&am... more The cold sintering process was applied as a suitable method to produce high relative density (> 90%) ZnO/MoS2 nanocomposite. The cold sintering process was done at 170 °C, 480 MPa for 45 min to fabricate ZnO/MoS2 nanocomposite in a bulk form containing 1–5% MoS2. In addition to examining the effective parameters of the process, the proper solvents in cold sintering of ZnO/MoS2 nanocomposite were investigated. The XRD, FTIR, and RAMAN results affirmed the removal of added solvent and the absence of any secondary phase or unknown component in the cold-sintered ZnO/MoS2 nanocomposite. The SEM and EDX results illustrated that to improve the MoS2 nanoparticle homogeneous distribution through the ZnO powders, a new three-component solvent (acetic acid-DMSO-water) with enhanced viscosity should be exerted. Increasing MoS2 nanoparticles resulted in a slight reduction in the final density of the nanocomposite as 5% MoS2 decreased the relative density from 95.2 to 90.9%. The TGA/DTA curves proved that the thermal stability of the fabricated nanocomposite was up to 450 °C. Alongside the bulk form of the produced nanocomposite, UV–visible investigations illustrated that the MoS2 nanoparticles enhanced the ZnO substrate's visible light absorption, indicating the potential of the cold-sintered ZnO/MoS2 nanocomposite for development in optical applications.

The ZnO/MoS2 nanocomposites were fabricated by a cold sintering process using a three-component s... more The ZnO/MoS2 nanocomposites were fabricated by a cold sintering process using a three-component solvent to produce high-density bulks (>90%). The effect of 1-5% MoS2 nanoparticles on mechanical properties (strength, elastic modulus, fracture toughness, and hardness) and tribological properties (mass loss, friction of coefficient, and wear rate) of the material was investigated. The 1% MoS2 improved the hardness and fracture toughness of nanocomposite by 2.22 GPa and 2.33 MPa√m, respectively, with a 23% enhancement in the wear resistance by 1.55×10 −5 mm 3 /N.m. Further increase in the nanoparticle's value caused a reduction in mechanical properties; however, the nanocomposite's friction coefficient was proportionally reduced with MoS2 enhancement up to 0.26. The MoS2 nanoparticles, despite the formation of smoother surfaces, have progressed the adhesive mechanism.

Materials Chemistry and Physics

Synthesis and Sintering

A novel Mg-0.7Ca alloy was prepared by the mechanical alloying (MA) process. Different variables ... more A novel Mg-0.7Ca alloy was prepared by the mechanical alloying (MA) process. Different variables were examined in order to obtain the optimum sample with the best milling behavior and potential sinterability. The structural studies were carried out using X-ray Diffractometer (XRD) and scanning electron microscopy (SEM). Crystallite size and lattice strain of the milled samples were examined by Scherrer and Williamson-Hall methods in order to finalize the investigation. The optimum milling time was found to be 60 minutes. In addition, a starch-containing sample with a fraction of 2.5 weight percent seemed to have the best microstructural properties, based on SEM observations and crystallite size assessments. Due discussions about the effective phenomena during the mechanical alloying were also included.

Proceedings of the Institution of Mechanical Engineers. Part L. Journal of Materials: Design and Applications, 2017