1. Engineering Center for Superlubricity, Ji Hua Laboratory, Foshan, P. R. China
2. College of Mechanical and Vehicle Engineering, Chongqing University, Chongqing, P. R. China
3. College of Intelligent Manufacturing and Automotive, Chongqing College of Electronic Engineering, Chongqing, P. R. China
4. State Key Laboratory of Tribology in Advanced Equipment, Tsinghua University, Beijing, P. R. China