Dry sliding wear behavior of nano-sized SiC pins against SiC and Si3N4 discs

Micro- and nano-sized hot-pressed silicon carbide pins have been characterized by room-temperature unlubricated disk-on-pin tribological tests on hot-pressed silicon carbide and silicon nitride discs. The mean grain size was shown not to influence the steady state friction coefficient. The mean grain size clearly affected the disc wear rate: the finer was the grain size the lower was the disc wear rate. No impact of the grain size was observed on the pin wear rate. The basic wear mechanisms were grain fracture and fine abrasion. By depth-sensing indentation, it was shown that a possible explanation of the different wear behaviour between micro- and nano-sized silicon carbide are the values of mechanical properties, especially hardness, when they are measured on volumes scaling with the material microstructure.