Microstructure, formation mechanism and properties of plasma-sprayed Cr7C3-CrSi2-Al2O3 coatings
(1. Key Laboratory for New Type of Functional Materials in Hebei Province, School of Materials Science and Engineering, State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Tianjin Key Laboratory of Materials Laminating Fabrication and Interface Control Technology, Hebei University of Technology, Tianjin 300401, China;
2. Integrated Computational Materials Research Centre, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 201899, China)
2. Integrated Computational Materials Research Centre, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 201899, China)
Abstract: The Cr7C3-CrSi2-Al2O3 composite coatings were prepared by plasma spraying Cr7C3-CrSi2-Al2O3 and Al-Cr2O3-SiC composite powders, respectively. The microstructure, formation mechanism and properties of the two Cr7C3-CrSi2-Al2O3 composite coatings obtained by plasma spraying were investigated, and the reaction mechanism of the Al-Cr2O3-SiC system was explored. The results show that the coating obtained by plasma spraying Al-Cr2O3-SiC composite powders had thinner lamella and more tortuous interlayer interface, and the in-situ synthesized Cr7C3, CrSi2 and Al2O3 in the coating were all nano-crystallines. Compared with the Cr7C3-CrSi2-Al2O3 coating prepared by plasma spraying Cr7C3-CrSi2-Al2O3 composite powders, the plasma-sprayed Cr7C3-CrSi2-Al2O3 coating obtained from Al-Cr2O3-SiC composite powders had higher density, higher microhardness (increased by 20%), better fracture toughness and lower wear rate (reduced by 28%).
Key words: plasma spraying; in-situ synthesis; nanostructure; strengthening and toughening; wear resistance