Sliding wear of TiAl intermetallics against steel and ceramics of Al 2O 3, Si 3N 4 and WC/Co

Abstract

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 Al 2O 3, Si 3N 4 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/Al 2O 3 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 Si 3N 4. 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 Si 3N 4 and Al 2O 3 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 Al 2O 3 and Si 3N 4 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.