The graphite （Gr）/MoS2 reinforced Mg self-lubricating composites were prepared through powder metallurgy. The composites were characterized for microstructure, physical, mechanical and wear properties. Gr/MoS2 p...The graphite （Gr）/MoS2 reinforced Mg self-lubricating composites were prepared through powder metallurgy. The composites were characterized for microstructure, physical, mechanical and wear properties. Gr/MoS2 phase in the composites was identified by XRD analysis. Microstructural observation showed that the Gr/MoS2 particles were homogeneously dispersed within the magnesium matrix. Micro-hardness was measured using an applied load of 5 g with a dwell time of 15 s at room temperature. Hardness of all the composites was measured to be in the range of VHN 29？34. The mechanical properties were studied using micro-hardness, tensile and compression tests. A fractographic analysis was performed using scanning electron microscope. The highest values of hardness, compressive strength and tensile strength were attained using Mg-10MoS2 composite. A pin-on-disk tribometer was used to measure the friction coefficient and the wear loss of the sintered composites. In addition to that, the friction and wear mechanism of the composites were systematically studied by worn surface characterization and wear debris studies using SEM analysis. The reduced friction coefficient and wear loss were achieved in MoS2 rather than Gr.展开更多
Multiwalled carbon nanotubes （MWCNTs） reinforced Cu-Sn alloy based nanocomposite was developed by powder metallurgy route. The mass fraction of CNTs was varied from 0 to 2% in a step of 0.5%. The developed nanocompo...Multiwalled carbon nanotubes （MWCNTs） reinforced Cu-Sn alloy based nanocomposite was developed by powder metallurgy route. The mass fraction of CNTs was varied from 0 to 2% in a step of 0.5%. The developed nanocomposites were subjected to density, hardness, electrical conductivity, and friction and wear tests. The results reveal that the density of nanocomposite decreases with the increase of the mass fraction of CNTs. A significant improvement in the hardness is noticed in the nanocomposite with the addition of CNTs. The developed nanocomposites show low coefficient of friction and improved wear resistance when compared with unreinforced alloy. At an applied load of 5 N, the coefficient of friction and wear loss of 2%CNTs reinforced Cu-Sn alloy nanocomposite decrease by 72% and 68%, respectively, compared with those of Cu-Sn alloy. The wear mechanisms of worn surfaces of the composites are reported. In addition, the electrical conductivity reduces with the increase of the content of CNTs.展开更多
The corrosion and tribocorrosion behavior of Ti6Al4V/xTiN(x=0,5,10 and 15,vol.%)composites fabricated by solid-state sintering and their relationship with the microstructure and microhardness were investigated.Simulat...The corrosion and tribocorrosion behavior of Ti6Al4V/xTiN(x=0,5,10 and 15,vol.%)composites fabricated by solid-state sintering and their relationship with the microstructure and microhardness were investigated.Simulated body conditions such as a temperature of 37℃ and a simulated body fluid were used.The main results demonstrated a microstructural change caused by theα-Ti stabilization due to solid-solution of nitrogen(N)into the titanium(Ti)lattice,producing a maximum hardening effect up to 109%for the Ti64 matrix by using 15 vol.%TiN.Corrosion potentials of composites changed to more noble values with the TiN particle addition,while corrosion current density of samples increased as an effect of the remaining porosity,decreasing the corrosion resistance of materials.However,changes to a less passive behavior were observed for samples with 15 vol.%TiN.The non-passive behavior of composites resulted in the reduction of the potential drops during rubbing in tribocorrosion tests.Besides,an improvement of up to 88%of the wear rate of composites was seen from the solid-solution hardening.The results allowed to understand the relationship between composition and sintering parameters with the improved tribocorrosion performance of materials.展开更多
A new process of WC-Co cemented carbide was developed by using nano-grained W（Co, C） composite powders as raw materials processed by high-energy ball milling. X-ray diffraetion（XRD）, differential thermal analysis ...A new process of WC-Co cemented carbide was developed by using nano-grained W（Co, C） composite powders as raw materials processed by high-energy ball milling. X-ray diffraetion（XRD）, differential thermal analysis （DTA）, thermo-gravimetrie （TG） analysis and coercive forces of the sintered samples were adopted to analyze the phase transformation and constitution, and the microstructures of sintered samples were characterized by scanning electron microscopy（SEM）. The results show that the as-milled powders are transformed into transitional phases W2C and η （Co3W3C or Co6W6C） during sintering, and finally transformed into WC and Co phases completely at 1 250℃ for 30 min, and a large number of fibrous WC grains with about 1.2μm in length and 100 nm in radial dimension are formed in the sintered body at 1 300 ℃.展开更多
The bulk A1-12 Si eutectic composites were fabricated through a conventional liquid metal casting route, especially with the help of ultrafine ceramic powders made by self-propagating high-temperature synthesis （SHS...The bulk A1-12 Si eutectic composites were fabricated through a conventional liquid metal casting route, especially with the help of ultrafine ceramic powders made by self-propagating high-temperature synthesis （SHS） process. The SHS powders were fabricated by the chemical reaction between micro-sized SiC and A1 particles at very high combustion temperatures, producing the coarse A1 particles （several tens of microns） containing ultrafine SiC ceramic particles. Microstructural observation revealed that the addition of ultrafine SiC particles has a crumbling tendency of Si eutectic phase. It is suggested that the casting method combined with SHS process is promising for fabricating the Al-based MMC with ultrafine ceramic particles.展开更多
文摘The graphite （Gr）/MoS2 reinforced Mg self-lubricating composites were prepared through powder metallurgy. The composites were characterized for microstructure, physical, mechanical and wear properties. Gr/MoS2 phase in the composites was identified by XRD analysis. Microstructural observation showed that the Gr/MoS2 particles were homogeneously dispersed within the magnesium matrix. Micro-hardness was measured using an applied load of 5 g with a dwell time of 15 s at room temperature. Hardness of all the composites was measured to be in the range of VHN 29？34. The mechanical properties were studied using micro-hardness, tensile and compression tests. A fractographic analysis was performed using scanning electron microscope. The highest values of hardness, compressive strength and tensile strength were attained using Mg-10MoS2 composite. A pin-on-disk tribometer was used to measure the friction coefficient and the wear loss of the sintered composites. In addition to that, the friction and wear mechanism of the composites were systematically studied by worn surface characterization and wear debris studies using SEM analysis. The reduced friction coefficient and wear loss were achieved in MoS2 rather than Gr.
文摘Multiwalled carbon nanotubes （MWCNTs） reinforced Cu-Sn alloy based nanocomposite was developed by powder metallurgy route. The mass fraction of CNTs was varied from 0 to 2% in a step of 0.5%. The developed nanocomposites were subjected to density, hardness, electrical conductivity, and friction and wear tests. The results reveal that the density of nanocomposite decreases with the increase of the mass fraction of CNTs. A significant improvement in the hardness is noticed in the nanocomposite with the addition of CNTs. The developed nanocomposites show low coefficient of friction and improved wear resistance when compared with unreinforced alloy. At an applied load of 5 N, the coefficient of friction and wear loss of 2%CNTs reinforced Cu-Sn alloy nanocomposite decrease by 72% and 68%, respectively, compared with those of Cu-Sn alloy. The wear mechanisms of worn surfaces of the composites are reported. In addition, the electrical conductivity reduces with the increase of the content of CNTs.
基金the University of Guadalajara for the support during the development of this researchsupported by CONACyT, México [CB-2017-2018-11813]by the State Council of Science and Technology of Jalisco (COECYTJAL), México [8205-2019]
文摘The corrosion and tribocorrosion behavior of Ti6Al4V/xTiN(x=0,5,10 and 15,vol.%)composites fabricated by solid-state sintering and their relationship with the microstructure and microhardness were investigated.Simulated body conditions such as a temperature of 37℃ and a simulated body fluid were used.The main results demonstrated a microstructural change caused by theα-Ti stabilization due to solid-solution of nitrogen(N)into the titanium(Ti)lattice,producing a maximum hardening effect up to 109%for the Ti64 matrix by using 15 vol.%TiN.Corrosion potentials of composites changed to more noble values with the TiN particle addition,while corrosion current density of samples increased as an effect of the remaining porosity,decreasing the corrosion resistance of materials.However,changes to a less passive behavior were observed for samples with 15 vol.%TiN.The non-passive behavior of composites resulted in the reduction of the potential drops during rubbing in tribocorrosion tests.Besides,an improvement of up to 88%of the wear rate of composites was seen from the solid-solution hardening.The results allowed to understand the relationship between composition and sintering parameters with the improved tribocorrosion performance of materials.
基金Project (50474049) supported by the National Natural Science Foundation of China
文摘A new process of WC-Co cemented carbide was developed by using nano-grained W（Co, C） composite powders as raw materials processed by high-energy ball milling. X-ray diffraetion（XRD）, differential thermal analysis （DTA）, thermo-gravimetrie （TG） analysis and coercive forces of the sintered samples were adopted to analyze the phase transformation and constitution, and the microstructures of sintered samples were characterized by scanning electron microscopy（SEM）. The results show that the as-milled powders are transformed into transitional phases W2C and η （Co3W3C or Co6W6C） during sintering, and finally transformed into WC and Co phases completely at 1 250℃ for 30 min, and a large number of fibrous WC grains with about 1.2μm in length and 100 nm in radial dimension are formed in the sintered body at 1 300 ℃.
基金supported by the Korea Atomic Energy Research Institute (KAERI) R&D Program
文摘The bulk A1-12 Si eutectic composites were fabricated through a conventional liquid metal casting route, especially with the help of ultrafine ceramic powders made by self-propagating high-temperature synthesis （SHS） process. The SHS powders were fabricated by the chemical reaction between micro-sized SiC and A1 particles at very high combustion temperatures, producing the coarse A1 particles （several tens of microns） containing ultrafine SiC ceramic particles. Microstructural observation revealed that the addition of ultrafine SiC particles has a crumbling tendency of Si eutectic phase. It is suggested that the casting method combined with SHS process is promising for fabricating the Al-based MMC with ultrafine ceramic particles.
