Effect of Aging Treatment of Ni-Based/TiC Coatings by Induction Cladding

The effects of aging temperature and holding time on the microstructure and wear resistance of induction-clad nickel-based/TiC alloy coatings were investigated. The nickel-based/TiC alloy powder was induction-clad on to 35CrMo steel substrate. Optical microscope and scanning electron microscope equipped with energy-dispersive spectroscopy were used to study the microstructure of the coatings, while x-ray diffractometry was utilized to investigate the existing phases on the coatings. Micro-hardness and wear behavior were measured by digital micro-hardness tester and dry sliding wear tester, respectively. The results showed that the coatings are mainly composed of Ni₄B₃, (Fe,Ni)₂₃C₆, Fe-Cr-Ni, NiFe, Ni₂B and CrO_0.87 phases. As the rise of aging temperature and extension of holding time, the unstable compounds gradually turn into the stable compounds. Compared with the composite coating without heat treatment, the micro-hardness and wear resistance of the composite coating after heat treatment have been greatly improved. The composite coating with the process parameter of 530 °C for 8 h has the highest micro-hardness and the best wear resistance. The performance of the composite coating with the process parameter of 580 °C for 2 h is second only to that of the coating at 530 °C for 8 h. The wear mechanism of the composite coatings was discussed.