A combination of hard(SiCP)and soft(fly ash)particulate reinforcements could be a strategy to enhance combination of multiple properties of Magnesium and its alloys which otherwise suffer from low stiffness,low wear r...A combination of hard(SiCP)and soft(fly ash)particulate reinforcements could be a strategy to enhance combination of multiple properties of Magnesium and its alloys which otherwise suffer from low stiffness,low wear resistance,and many other critical properties.However,at present a comprehensive and robust map correlating different properties in particle-reinforced composites is much lacking.In this work,an industrial grade AZ91 magnesium alloy reinforced with hard SiC and soft fly ash particles(with 3 vol.%each),has been prepared using stir casting followed by hot extrusion at 325℃with a ratio of 21.5.Microstructure of the hybrid composite was characterized using optical and scanning electron microscopes.The composite exhibited a reduction in average grain size from 13.6 to 7.1μm,concomitantly an increase in Vickers hardness from 73 to 111 HV.The tension-compression yield asymmetry ratios of the unreinforced alloy and hybrid composite were 1.165 and 0.976,respectively indicating higher yield strength for the composite under compressive load.The composite exhibited 76%improvement in damping capacity under time sweep mode,and 28%improvement at 423 K under temperature sweep mode.The tribological characteristics of the composite under dry sliding conditions at sliding speeds and loads in the range of 0.5 to 1.5 m s^(-1)and 10 to 30 N,respectively showed higher wear resistance than the unreinforced alloy.The composite showed 23%improvement in sliding wear resistance at a load of 20 N and a speed of 1 m s^(-1).Finally,efforts have been made to understand the influence of one property on the other by developing statistical property correlation maps from the properties obtained in this study and from the literature.These maps are expected to help in the design of hybrid Metal Matrix Composites for a variety of targeted applications in different sectors.展开更多
A simple redox transformation between a vanadium(Ⅲ)metal complex and gold(Ⅲ)chloride aided by a cost-effective modified hydrothermal procedure has been adopted for the synthesis of Au-V_(2)O_(5)composite nanowires.T...A simple redox transformation between a vanadium(Ⅲ)metal complex and gold(Ⅲ)chloride aided by a cost-effective modified hydrothermal procedure has been adopted for the synthesis of Au-V_(2)O_(5)composite nanowires.The stability of pseudocapacitive electrode materials in acidic electrolytes is a major challenge.However,the synthesized Au-V_(2)O_(5)composite nanowires are stable in acidic electrolyte when compared to the precursor component,V_(2)O_(5).Electrochemical measurement shows a specific capacitance of 419 F g^(-1)at 1 A g^(-1)current density in 0.5 M H2SO4 solution for the synthesized composite nanowires.However,the precursor component V_(2)O_(5)shows a lower specific capacitance under identical conditions.The synthesized composite nanowires,as a pseudocapacitive electrode material,respond to a wide range of working potential windows(+1.6 V),resulting in maximum energy and power densities of 53.33 W h kg^(-1)and 3.85 kW kg^(-1)respectively.Moreover,the Au-V_(2)O_(5)nanowires show high cyclic stability(89%specific capacitance retention)for up to 5000 consecutive charge-discharge(CD)cycles at 10 A g^(-1)constant current density,due to the composite formation by redox transformation,which reflects the stability of the composite in acidic electrolyte.展开更多
文摘A combination of hard(SiCP)and soft(fly ash)particulate reinforcements could be a strategy to enhance combination of multiple properties of Magnesium and its alloys which otherwise suffer from low stiffness,low wear resistance,and many other critical properties.However,at present a comprehensive and robust map correlating different properties in particle-reinforced composites is much lacking.In this work,an industrial grade AZ91 magnesium alloy reinforced with hard SiC and soft fly ash particles(with 3 vol.%each),has been prepared using stir casting followed by hot extrusion at 325℃with a ratio of 21.5.Microstructure of the hybrid composite was characterized using optical and scanning electron microscopes.The composite exhibited a reduction in average grain size from 13.6 to 7.1μm,concomitantly an increase in Vickers hardness from 73 to 111 HV.The tension-compression yield asymmetry ratios of the unreinforced alloy and hybrid composite were 1.165 and 0.976,respectively indicating higher yield strength for the composite under compressive load.The composite exhibited 76%improvement in damping capacity under time sweep mode,and 28%improvement at 423 K under temperature sweep mode.The tribological characteristics of the composite under dry sliding conditions at sliding speeds and loads in the range of 0.5 to 1.5 m s^(-1)and 10 to 30 N,respectively showed higher wear resistance than the unreinforced alloy.The composite showed 23%improvement in sliding wear resistance at a load of 20 N and a speed of 1 m s^(-1).Finally,efforts have been made to understand the influence of one property on the other by developing statistical property correlation maps from the properties obtained in this study and from the literature.These maps are expected to help in the design of hybrid Metal Matrix Composites for a variety of targeted applications in different sectors.
基金DST INSPIRE(DST/INSPIRE/04/2015/003227),India for financial assistance。
文摘A simple redox transformation between a vanadium(Ⅲ)metal complex and gold(Ⅲ)chloride aided by a cost-effective modified hydrothermal procedure has been adopted for the synthesis of Au-V_(2)O_(5)composite nanowires.The stability of pseudocapacitive electrode materials in acidic electrolytes is a major challenge.However,the synthesized Au-V_(2)O_(5)composite nanowires are stable in acidic electrolyte when compared to the precursor component,V_(2)O_(5).Electrochemical measurement shows a specific capacitance of 419 F g^(-1)at 1 A g^(-1)current density in 0.5 M H2SO4 solution for the synthesized composite nanowires.However,the precursor component V_(2)O_(5)shows a lower specific capacitance under identical conditions.The synthesized composite nanowires,as a pseudocapacitive electrode material,respond to a wide range of working potential windows(+1.6 V),resulting in maximum energy and power densities of 53.33 W h kg^(-1)and 3.85 kW kg^(-1)respectively.Moreover,the Au-V_(2)O_(5)nanowires show high cyclic stability(89%specific capacitance retention)for up to 5000 consecutive charge-discharge(CD)cycles at 10 A g^(-1)constant current density,due to the composite formation by redox transformation,which reflects the stability of the composite in acidic electrolyte.
