The effect of rutile（TiO_2） content on the wear and microhardness properties of aluminium（Al）-based hybrid composites was explored. The proposed content of TiO_2（0, 4%, 8%, 12%, mass fraction） was blended to Al-...The effect of rutile（TiO_2） content on the wear and microhardness properties of aluminium（Al）-based hybrid composites was explored. The proposed content of TiO_2（0, 4%, 8%, 12%, mass fraction） was blended to Al-15% SiC composites through powder metallurgy（P/M） process. Wear test was conducted using pin-on-disc apparatus under dry sliding conditions. Fabricated preforms were characterized using X-ray diffractometer（XRD）, scanning electron microscope（SEM） and energy-dispersive X-ray spectrometer（EDS）. Optical micrographs of the composite preforms display uniform distribution of TiO_2 throughout the matrix. Quantitative results indicate that wear resistance and microhardness increase with the increase of TiO_2 content. SEM images unveil that high wear resistance is attributed to high dislocation density of deformed planes and high hardness of TiO_2. SEM images of wear debris display gradual reduction in mean size of debris when TiO_2 content increases. EDS spectra confirm the presence of oxide layer which obviously reduces the effective area of contact between the sliding surfaces thereby lowers the wear loss of composites. The observation concludes that delamination and adhesive wear are the predominant mechanisms.展开更多
In order to produce low-cost titanium(Ti)with high productivity,fundamental studies on producing metallic Ti from titanium dioxide(TiO2)in the cold pressed pellets were conducted by metallothermic reduction with an in...In order to produce low-cost titanium(Ti)with high productivity,fundamental studies on producing metallic Ti from titanium dioxide(TiO2)in the cold pressed pellets were conducted by metallothermic reduction with an indirect contact method.This paper focuses on discussing the mechanism of the reduction process and the relationships of RM(a revised reduction index)with reduction temperature,reduction time,and mole ratio of TiO2 to CaCl2(nTiO2/nCaCl2)in the pellets.The results show that metallic Ti was obtained from the reduction of TiO2 in the pellets by calcium(Ca)vapor;pellets were reduced homogenously and Ca vapor diffused into the porous pellets by Knudsen diffusion or the mixing diffusion of molecular diffusion and Knudsen diffusion at 1273 K;RM increased with the increases of temperature and reduction time and was 96.34%when TRedu=1273 K,tRedu=6 h,and nTiO2/nCaCl2=4;the reasonable nTiO2/nCaCl2 value is 3−5 for the pellets with enough strength and high RM.展开更多
文摘The effect of rutile（TiO_2） content on the wear and microhardness properties of aluminium（Al）-based hybrid composites was explored. The proposed content of TiO_2（0, 4%, 8%, 12%, mass fraction） was blended to Al-15% SiC composites through powder metallurgy（P/M） process. Wear test was conducted using pin-on-disc apparatus under dry sliding conditions. Fabricated preforms were characterized using X-ray diffractometer（XRD）, scanning electron microscope（SEM） and energy-dispersive X-ray spectrometer（EDS）. Optical micrographs of the composite preforms display uniform distribution of TiO_2 throughout the matrix. Quantitative results indicate that wear resistance and microhardness increase with the increase of TiO_2 content. SEM images unveil that high wear resistance is attributed to high dislocation density of deformed planes and high hardness of TiO_2. SEM images of wear debris display gradual reduction in mean size of debris when TiO_2 content increases. EDS spectra confirm the presence of oxide layer which obviously reduces the effective area of contact between the sliding surfaces thereby lowers the wear loss of composites. The observation concludes that delamination and adhesive wear are the predominant mechanisms.
基金Projects(51774071,50804007,51974073)supported by the National Natural Science Foundation of China。
文摘In order to produce low-cost titanium(Ti)with high productivity,fundamental studies on producing metallic Ti from titanium dioxide(TiO2)in the cold pressed pellets were conducted by metallothermic reduction with an indirect contact method.This paper focuses on discussing the mechanism of the reduction process and the relationships of RM(a revised reduction index)with reduction temperature,reduction time,and mole ratio of TiO2 to CaCl2(nTiO2/nCaCl2)in the pellets.The results show that metallic Ti was obtained from the reduction of TiO2 in the pellets by calcium(Ca)vapor;pellets were reduced homogenously and Ca vapor diffused into the porous pellets by Knudsen diffusion or the mixing diffusion of molecular diffusion and Knudsen diffusion at 1273 K;RM increased with the increases of temperature and reduction time and was 96.34%when TRedu=1273 K,tRedu=6 h,and nTiO2/nCaCl2=4;the reasonable nTiO2/nCaCl2 value is 3−5 for the pellets with enough strength and high RM.
