Effects of Boriding Treatment on the Surface Structure and Properties of 60NiTi Alloy
Author of the article:GUAN Lei 1 , TAN Cuicui 2 , CHEN Shuqun 2 , PENG Jian 3
Author's Workplace：1. AECC, Beijing Institute of Aeronautical Materials, Beijing 100095, China; 2. Faculty of Materials and Manufacturing, Beijing University of Technology, Beijing 100124, China; 3. State Key Lab of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China
Key Words：60NiTi alloy; pack boriding; thermodynamic calculation; wear resistance
Abstract：
With high hardness, low elastic modulus and good corrosion resistance, 60NiTi alloys have been regarded as an ideal candidates for next generation aerospace bearings. In this study, pack boriding experiments were performed on 60NiTi alloys at the temperature of 1 000 ℃ for 5 h to improve wear resistance. The surface microstructure, mechanical and friction properties were systematically studied. The boronised layer shows a multilayer structure of TiB 2 /NiTi 2 +TiB 2 /Ni 3 Ti with a total thickness of ~20 μm. After boriding treatment, the surface hardness of 60NiTi alloy is increased from 420 HV 0.2 to 2 600 HV 0.2 , while the coefficients of friction and wear rate are reduced by 39% and 92%, respectively, under the normal load of 20 N. The improved wear resistance of the borided specimens is achieved by the formation of boron oxide protective layers via shear-induced oxidation.
