1. State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical Physics Chinese Academy of Sciences Lanzhou 730000 China
2. School of Nuclear Science and Technology Lanzhou University Lanzhou 730000 China
3. Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Beijing 100049 China
4. School of Mechanical Engineering University of Science and Technology Beijing Beijing 100083 China
5. State Key Laboratory of Tribology in Advanced Equipment Tsinghua University Beijing 100084 China