Abstract
Active screen plasma nitriding (ASPN) has attracted interest from researchers and industries as it can overcome several intrinsic problems in direct current glow discharge plasma nitriding such as arcing, hollow cathode, edge effects and the strong temperature dependence on the shape of the samples. In this study, an advanced duplex system based on ASPN and chromium nitride coating was synthesised on 42CrMo4 steels. The effects of ASPN on the mechanical properties, nanoimpact resistance and scratch resistance at different load ranges were investigated. The results show that the surface hardness H, reduced elastic modulus Er and the ratios of H/Er and H3/E2r can significantly be improved at the testing load range from 5 to 100 mN. The enhanced nanoimpact and scratch resistance can be well correlated to the improved H/Er and H3/E2r.
The authors would like to thank the Southeast University Major Program Science and Research Guidance fund (grant no. 3212002102), the Opening Project of Jiangsu Key Laboratory of Advanced Metallic Materials (grant no. AMM201205) and the National Natural Science Foundation of China (grant nos. 11204031 and EC NMP3-SL-2008-213600) for their financial support.