Influence of TiN particles on the wear behavior of silicon nitride–based composites

The friction and wear behavior of Si₃N₄-based composites against AISI-52100 steel were investigated in the ball-on-disk mode in a nonlubrication reciprocation motion. It has been found that under the conditions used, all the ceramic components exhibited rather low friction and wear coefficients. For monolithic silicon nitride materials, high friction coefficients between 0.6 and 0.7 and wear coefficients between 1.63 × 10⁻⁸ and 1.389 × 10⁻⁶ mm³/N · m were measured. The contact load was varied from 100 to 300 N. By adding titanium nitride, the friction coefficients were reduced to a value between 0.4 and 0.5 and wear coefficients between 1.09 × 10⁻⁸ and 0.32 × 10⁻⁶ mm³/ N · m at room temperature. All materials and worn surfaces as well as wear debris were investigated by means of scanning electron microscopy, energy dispersive spectroscopy, x-ray diffraction, and transmission electron microscopy (TEM) before or after the tribological tests. The TEM micrographs of wear track revealed plastic deformation through twins and cracking along grain boundary which play an important role in the fracture mechanism.