FRETTING WEAR OF SELECTED CERAMICS AND CERMETS

Fretting experiments were performed on sialon ceramic, zirconia-toughened alumina ceramic, titanium carbonitride cermet and tungsten carbide-cobalt cemented carbide materials to determine their relative wear performance when tested against Cr-steel counterbodies. All of the materials, with the exception of the titanium carbonitride cermet, display fretting steady state coefficient of friction values similar to that of steel on steel. The wear behavior of the sialon/steel couple appears to involve transfer layers, indicating that tribochemical interactions play an important role in this case. Both the zirconia-toughened alumina/steel and tungsten carbide-cobalt cemented carbide/steel couples undergo abrasive wear during fretting testing, though the tungsten carbide-cobalt cemented carbide is worn to a lesser degree than the zirconia-toughened alumina. The titanium carbonitride cermet/steel couple, on the other hand, undergoes a special abrasive wear mechanism in which hard particles from the cermet embed themselves in the soft steel, where they preferentially abrade the cermet while protecting the steel.