Effects of content of SiO_2 particles on tribological behavior of Cu-matrix friction materials

To investigate the relationship between dandification mechanism of SiO2 particles and materials performance under different friction speeds,Cu-graphite-SiO2 sintered materials were prepared through powder metallurgy.The tests were conducted on a pin-on-disk tester in speed range of 7.8-47.1 m/s.The results demonstrate that the effects of SiO2 on the friction and wear performance of the materials are closely related to the friction speed.At low friction speed,the friction coefficient increases with increasing content of SiO2 particles,this is attributed to the effect of SiO2 scratch,which can improve the friction force remarkably under static load.However,the wear rate is not sensitive to the content of SiO2 particles.At high friction speed,the SiO2 particles are broken by impact action and embedded in the matrix softened at high temperature,which results in reduction of scratch influence,and makes the friction coefficient insensitive to SiO2 content.The increase of surface hardness causes the wear rate to fall with increasing content of SiO2 particles.