Sliding wear of TiAl intermetallics against steel and ceramics of Al2O3, Si3N4 and WC/Co

Unlubricated wear tests have been performed with a ball-on-disc tribometer, in which, a disc sample of gamma-based titanium aluminide (TiAl) was sliding against an 8 mm diameter ball made of steel and ceramics of Al2O3, Si3N4 and WC/Co. Experimental results have shown that sliding wear property of the investigated titanium aluminide is strongly dependent on the counterface materials. Under the testing conditions, wear loss of TiAl in the contact pair of TiAl/Al2O3 is the highest, and that in the pair of TiAl/steel is the lowest. There is no clear difference in wear performance of TiAl when the counterface ball is made of WC or Si3N4. In addition to wear loss of TiAl, the ball slider was also worn and the amount of wear loss varied significantly with the materials for the ball. Ceramics of Si3N4 and Al2O3 suffered severe wear loss regardless of their high hardness and generally believed high wear resistance. In contrast, wears of WC and steel were found to be much smaller. From a tribological point of view, sliding contact of titanium aluminide intermetallics against Al2O3 and Si3N4 may not be optimal designs since these contact pairs can result in very high overall wear loss. Based on XRD, SEM and EDX analysis results, the mechanisms of TiAl wear loss in different contact pairs are discussed.