Sliding friction and wear of structural ceramics

Abstract

Further analysis has been performed on SiC and partially stabilized ZrO₂ specimens employed in a previous study of sliding friction and wear. Wear volumes have been measured, wear debris has been studied by X-ray diffraction and transmission electron microscopy, and comparative X-ray diffraction studies have been performed on worn and unworn surfaces. There is no correlation between the wear during running-in and the steady-state coefficient of friction established by this process. ZrO₂-ZrO₂ friction couples wear much faster than SiC-SiC couples, which in turn wear faster than ZrO₂-SiC couples. In these last couples wear occurs mostly on the ZrO₂ member, but does not measurably promote the tetragonal to monoclinic phase transformation. Adding graphite to SiC reduces the wear of SiC-SiC couples somewhat, but improving their initial surface finish has the opposite effect. All wear debris exhibited a bimodal particle-size distribution, which observation can be rationalized with the wear surface topographies reported previously.