Nano-TiO2 reinforced CoCr matrix wear resistant composites and high-temperature tribological behaviors under unlubricated condition
Gongjun Cui, Yanping Liu, Sai Li, Huiqiang Liu, Guijun Gao, Ziming Kou
Abstract
Abstract The CoCrMo matrix composites with nano-TiO 2 particle (2 wt.%, 4 wt.% and 6 wt.%) were fabricated by using a powder metallurgy technique (P/M), and the nano-TiO 2 content was optimized in matrix. The microstructures, mechanical and high-temperature tribological properties of the synthesized composites were systematically studied. Friction and wear behaviors were studied by using a disk-on-ball tribo-tester sliding against Si 3 N 4 ceramic ball from room temperature (23 o C) to 1000 o C in air. TiO 2 obviously strengthened the hardness and high-temperature wear resistance of composites. It was attributed to the high load-carrying capacity of matrix, in-situ formed high-temperature solid lubricants and stable oxides film on the wear tracks. 4 wt.% TiO 2 was the critical threshold at which there was a transition of tribological properties over a broad temperature range. The composite containing 4 wt.% nano-TiO 2 exhibited the most reasonable high-temperature friction coefficient and wear rate at all testing temperatures. At different testing temperatures, the composites showed different wear mechanisms.