1. School of Petrochemical Technology, Lanzhou University of Technology, Lanzhou 730050, P. R. China
2. Key Laboratory of Science and Technology on Wear and Protection of Materials, Lanzhou Institute of Chemical Physics, Chinese Academy of Science, Lanzhou 730000, P. R. China
3. State Key Laboratory of Solidification Processing, Center of Advanced Lubrication and Seal Materials, Northwestern Polytechnical University, Xi’an, Shaanxi 710072, P. R. China
4. Yantai Zhongke Research Institute of Advanced Materials and Green Chemical Engineering, Yantai 264000, P. R. China