Microstructure and tribology performance of laser cladded Ni60+h-BN coatings on Ti-6Al-4V alloy at high temperature

ABSTRACTWith the expansion of the application range of titanium alloys, the wear protection problem has become increasing prominent due to their poor wear resistance, especially in high temperature environments. To solve this problem, in this work, Ni60+h-BN coatings on Ti-6Al-4V (TC4) alloys were prepared using laser cladding technique. The results indicated that the Ni60+h-BN coatings mainly contain the phases of NiTi2, TiN, TiB, (Si, Al)2Cr and solid solution Fe0.2Ni4.8Ti5, possessing much higher micro-hardness (1055.36 ± 16.33 HV0.22) than TC4 substrates (309 ± 10 HV0.2), and the Ni60+h-BN coatings show the excellent wear resistance and antifriction properties at 600 °C with the dominant worn mechanism of slight adhesive wear and oxidative wear. Through the analysis of XPS, SEM and EDS, most of the initial h-BN particles in the mixed powders were decomposed and the reinforcements of TiB and TiN were in-situ synthesized after high powder laser irradiation, which plays a role in wear-resistance while th...