Structure and High-temperature Wear Behavior of Zr Modified Silicide Coatings Prepared on TC4 Alloy

Zr modified silicide coatings were prepared on TC4 alloy by Si-Zr co-deposition, the wear behavior of the coatings were investigated at 600℃, and the wear mechanisms were discussed. The results show that the obtained coating has a multi-layer structure, consisting of a（Ti, X）Si2（X represents Zr, Al and V elements） outer layer, a Ti Si middle layer and an inner layer composed of a mixture of Ti5 Si4+Ti5 Si3. Addition of Zr in the pack mixtures can reduce the residual stress in the coating by lowering the coating growth rate, leading to a more compact coating structure. The micro-hardness of the coating is obviously higher than that of TC4 alloy, which shows a decrease tendency from the coating surface to its substrate. The high temperature wear tests reveal that the Zr modified silicide coating can offer effective protection for TC4 alloy at high temperatures. When using GCr15 ball as the counterpart, very slight wear occurred on the worn surface of the coating, and the main wear manners should be the transfers of GCr15 to the coating surface besides a certain extent of oxidation wear. Sliding against Al2 O3 ball, the main wear mechanisms of the coating are considered to be plough wear, fatigue wear, adhesive wear, and oxidation wear.