Promoted low-temperature plasma nitriding for improving wear performance of arc-deposited ceramic coatings on Ti6Al4V alloy via shot peening pretreatment
Hui Xiao, Xuanyu Liu, Qinghua Lu, Te Hu, Yue Hong, Cong Li, Ruijun Zhong, Wanglin Chen
Abstract
In the present work, the combination of shot peening (SP), low-temperature plasma nitriding (PN) and arc deposition (AD) is proposed to improve the wear performance of Ti6Al4V alloy. The low-temperature rapid nitriding of Ti6Al4V alloy was realized by SP pretreatment to obtain a desired nitrided interlayer. The high-density structural defects produced by SP pretreatment promote the nitriding kinetics at low temperature. The nitrided interlayer consists of an outermost TiN/Ti2N compound layer and an inner diffusion layer, showing a diffusion-typed hardness-profile, which is beneficial for the enhancing of adhesion strength and load-bearing capacity. Moreover, the improvement of adhesion strength is associated closely with TiN/Ti2N compounds which can provide heterogeneous nucleation sites for AD coating with a high hardness of about 3100 HV. The high bearing-load capacity and adhesion strength can ensure the excellent wear resistance of SP-PN-AD-coated sample when compared to single AD or PN-AD samples, especially under intensive wear load conditions. The present work provides a new insight into surface hardening of Ti alloys.