Investigation on the fretting wear behavior of titanium alloy under different atmospheres by an in situ XPS spectrometry

In this paper, a systematic experimental investigation concerning the fretting wear behavior of Ti6Al4V titanium alloy under the nitrogen, argon and air atmospheres is reported. An in-situ XPS analysis test combined with a self-designed high precision fretting wear tester was employed to probe the tribo-chemical state. The fretting wear volume and fretting wear mechanism under different atmospheres were analyzed and the correlations of tribo-chemical state with the fretting wear behavior were discussed. Results suggest that the working atmosphere has a significant effect in determining the formation of tribo-chemical products on the worn scars and then the fretting wear resistance depending on fretting run regimes. In the PSR, the working atmosphere has little effect on the tribo-chemical reaction and then the fretting wear. While in MFR, the worn scars under the nitrogen atmosphere show the highest fretting wear volume but the lowest fretting wear volume under the argon atmosphere. In SR, Ti6Al4V titanium alloy under the nitrogen and argon atmosphere presents a much high fretting wear volume, which may be due to the formation of titanium nitrides and Ti 2 O 3 and TiO, respectively. In contrast, under the air atmosphere, Ti6Al4V titanium alloy presents the lowest fretting wear volume, which could be attributed to the protective effect of a compacted TiO 2 oxidized film.