EFFECT OF DOPING ELEMENTS ON FRICTION AND WEAR PROPERTIES OF SELF-MATED Si{sub}3N{sub}4 SLIDING

摘要

Since a very low friction coefficient was observed in water with Si{sub}3N{sub}4 and SiC sliding against itself, the water lubricant ion of ceramics has drawn increasing attention and shows high potential for engineering applications such as journal hearings of water pumps and mechanical face seals for water [1]. The low friction mechanism of self-mated Si{sub}3 N{sub}4 or SiC in water is explained by the wear during running-in, which forms smooth wear surfaces. This wear is called as tribochemical wear, and is explained by the following formula [2]: Si{sub}3N{sub}4 + H{sub}2O→SiO{sub}2 + NH{sub}3; SiC+H{sub}2O→ SiO{sub}2 + CH{sub}4; SiO{sub}2 + H{sub}2O→ Si(OH){sub}4. However engineering ceramics generally contain doping elements for sintering aides and material property improvements. It is not clear how such elements affect the reactions. This study aims at clarifying the effect of doping elements on the friction and wear properties of self-mated Si{sub}3N{sub}4 in water.