Effects of sintering aids and solid lubricants on tribological behaviours of CMC/Al2O3 pair at 650°C

Ten kinds of self-lubricating composites with different amounts of sintering aids and solid lubricants in Al2O3 matrix were fabricated by her-pressed sintering. Their friction and wear behaviours in unlubricated sliding against Al2O3 were tested by using a pin-on-disk wear tester at 650 degrees C. It was shown that the amount of sintering aids strongly affected friction coefficient and wear rate of the Al(2)O(3)20-Ag20CaF(2) composite, the appropriate amount of sintering aids was 10 wt% for beneficial effect on the reduction of wear at 650 degrees C. Also it was shown that the addition of equal quantities of Ag and CaF2 in Al2O3 matrix can promote the formation of the well-covered lubricating film, and effectively reduce the friction and wear. The composite with 40 wt% of lubricants (20 wt% Ag, 20 wt% CaF2) presented an optimum tribological behavior at 650 degrees C (friction coefficient mu is about 0.3, wear rates are about 4 x 10(-6) mm(3)/N m and 5 x 10(-7) mm3/N m for the disk and pin, respectively).