Microstructure and wear resistance of composite coating by laser cladding Ni60A/B4C pre-placed powders on Ti-6Al-4V substrate

Abstract

The composite coatings were fabricated by laser cladding Ni60A/B4C pre-placed powders on the surface of Ti-6Al-4V alloy for improving wear resistance and hardness of the substrate. In this research, the composite coatings were studied by means of X-ray diffraction, scanning electron microscope and energy dispersive spectrometer. The sliding wear tests were performed using MM200 wear test machine. The hardness of the coatings was tested by HV-1000 hardness tester. After laser cladding, it was found that there was a good metallurgical bond between the laser cladding coating and Ti-6Al-4V substrate. The composite coatings were mainly composed of the matrix of γ-Ni and a little Ni3Ti and the reinforcements of TiB2, TiC and CrB. The hardness of the sample of Ni60A-5B4C was approximately 2.5–3.5 times that of the Ti-6Al-4V substrate. The hardness of the sample of Ni60A-10B4C was 30% higher than that of sample 1. The wear resistance of samples 1 and 2 were 11 times and 10 times that of the substrate, respectively.

Keywords

• composite coating
• hardness
• laser cladding
• microstructure
• wear resistance