High temperature tribology of TiAlN PVD coating sliding against 316L stainless steel and carbide-free bainitic steel

Reciprocating sliding wear tests were performed on TiAlN coating against 316L stainless steel and carbide-free bainitic steel at temperatures of 40, 400 and 800 °C. The results indicate that material transfer is more pronounced for the softer stainless steel at lower temperatures but at 800 °C, carbide-free bainite exhibits relatively more material transfer. Friction coefficient of stainless steel increases when temperature increases. However, for carbide-free bainite, there is a reduction in friction coefficient at elevated temperatures. This can be attributed to formation of an easily sheared iron oxide layer at elevated temperatures. In case of stainless steel, generation of a thin tribofilm containing aluminium oxide and oxidised transferred material can protect the TiAlN coating against wear at 800 °C.