Mechanical and tribological properties of Si and W doped diamond like carbon (DLC) under dry reciprocating sliding conditions
Mingwen Bai, Liuquan Yang, Jiayu Li, Luo Lun, Shi‐Kuan Sun, Beverley J. Inkson
Abstract
The mechanical and tribological properties of three types of diamond like carbon (DLC) coatings, i.e., non-doped, Si-doped, and W-doped DLC, are evaluated. Dry reciprocating sliding wear tests were performed to evaluate the effect of sliding frequency/velocity on friction, adhesion, and wear. The degree of graphitization of non-doped and W-doped DLC increases with sliding velocity, which results in a lower coefficient of friction (COF), and a decrease in wear rate. Si-doped DLC, however, exhibits distinct friction behaviour, with increasing COF and severe fluctuations in friction at higher sliding velocities. In Si-DLC frictional heating drives the formation of an oxide-rich tribofilm and large amounts of Si-rich oxide wear debris that are both adhesive and abrasive. The oxide-rich tribofilm, and lack of surface graphitization, result in the severe fluctuations of Si-DLC friction via stick-slip and surface fracture/wear mechanisms, and significantly increased COF and wear rates at higher sliding velocities.