The friction and wear of Cu-based silicon carbide particulate metal matrix composites for brake applications

The purpose of this study was to investigate the tribological characteristics of several Cu-based SiC particulate metal matrix composites (pMMCs) synthesized from copper-coated SiC particles. Pin-on-disk tests were done to compare the wear and friction properties of hemispherically tipped pMMC pins with those for grey cast iron machined from an automotive brake rotor. The sliding counterfaces in the tribotests were semi-metallic and low metallic friction materials of the type used in commercial brake pads. Against both of these counterfaces, the pMMCs exhibited lower wear rates than cast iron. It was also observed that the friction coefficients of the pMMCs against the friction material counterfaces were comparable with those for cast iron. Wear mechanisms for the CuSiC pMMC materials were studied using scanning electron and optical microscopy of the wear scars. The influence of SiC particle size and type of friction material counterface on tribological behavior of the pMMCs was also studied, as was the effect of various interfacial coatings designed to improve bonding of the matrix to the particles. A model of the wear of this pMMC material, taking into account the various material parameters, will be presented. (C) 1997 Elsevier Science S.A.