Effect of carbon on tribological property of plasma carburized TiAl based alloy
(1.北京市北京科技大学材料物理与化学系
2.山西省太原市太原理工大学表面工程研究所
3.Department of Materials Physics and Chemistry, University of Science and Technology Beijing,Beijing 100083, China
4.Research Institute of Surface Engineering, Taiyuan University of Technology, Taiyuan 030024, China)
2.山西省太原市太原理工大学表面工程研究所
3.Department of Materials Physics and Chemistry, University of Science and Technology Beijing,Beijing 100083, China
4.Research Institute of Surface Engineering, Taiyuan University of Technology, Taiyuan 030024, China)
Abstract: Plasma carburization at two different methane-to-argon gas ratios (5:5 and 6:5) was carried out on the cast TiAl based alloy of Ti-46.5Al-2.5V-1Cr (mole fraction, %) in order to enhance its wear resistance. The results show that after carburization under both carburizing atmospheres, Ti2AlC and TiC are the main carbides in the carburized layer and the value of surface hardness reaches more than HK 822, but for the carburized TiAl treated at CH4？Ar of 5？5, the surface carbon concentration is higher and the carburized depth is slightly thicker than that of alloy carburized at CH4？Ar of 6？5. The result of the ball-on-disk test against hardening-steel counter bodies shows that the wear resistance of the TiAl based alloy carburized under two different carburizing atmospheres is improved compared with non-carburized TiAl. The tribological property is related to the carbon content, and the carburized layer obtained at CH4:Ar of 5:5 possesses a stable friction coefficient, lower volume loss or wear rate and narrow wear scar. The characteristic of the carburized layer was examined by using optical microscopy, glow discharge spectrum and micro-hardness tester.
Key words: TiAl based alloy; plasma carburization; carburizing atmosphere; carbon concentration; tribological property