Influence of a pre-existing glaze layer on the fretting-wear response of HS25 cobalt-based alloy subjected to various temperature conditions

The wear behavior of metallic alloys at variable temperature is a crucial aspect in many industrial components such as turbines and compressors in aircraft engines. In particular, the blade/disk contact is subjected to a cyclic thermal loading combined with a cyclic sliding (fretting) which can significantly damage the interface. The objective of this work is to investigate the behavior of the interface during such variable temperature sliding sequence. Results show that the protective oxide layer (glaze layer) formed at high temperature is destroyed at low temperature within a latency time. However, the high-temperature glaze layer induces a reduction of the wear volume at lower temperature compared to a standard fretting test performed at a fixed temperature condition (without initial glaze layer formation). When the glaze layer is turned into debris, it enriches the debris bed with a high proportion of cobalt element. This high concentration of cobalt element in the third body layer can clarify the lower steady state wear regime compared to an equivalent fixed temperature test condition.