1. State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical Physics Chinese Academy of Sciences Lanzhou 730000 China
2. Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Beijing 100049 China
3. Qingdao Center of Resource Chemistry and New Materials Qingdao 266100 China
4. Center of Advanced Lubrication and Seal Materials Northwestern Polytechnical University Xi'an Shaanxi 710072 P. R. China
5. Hubei Key Laboratory of Hydroelectric Machinery Design & Maintenance Three Gorges University Yichang 443002 China