Microstructure Characterisation and Mechanical Properties of Ti/TiBCN Coatings Fabricated by Laser Cladding
L.Y. Wu, Y.X. LI, Z.Y. Zhao, P.K. BAI, Z.H. LI, J. LI, P.C. Huo and W.B. Du
Ti/TiBCN composite coatings were deposited on Ti6Al4V alloy using laser cladding technology. The comprehensive effects of laser specific energy on the microstructure, hardness, corrosion resistance and wear resistance of the Ti/TiBCN composite laser clad coatings were investigated. The phase characteristics of the coatings mainly comprise of Ti, Ti/ TiBCN, TiC, Ti3Al, TiN and TiB2. The microstructure of coatings consists of coarse and fine dendritic crystals structure which is centrally symmetric structure with rod-like shape. The Ti/TiBCN composite coating cladding materials can be formed into homogeneous coatings at the laser specific energy of 330 J/mm2. The metallurgical pores can be minimized but cannot be completely avoided by adjusting the scanning speed. The highest microhardness of the Ti/TiBCN composite laser clad coating was 1250 HV0.2, which was 3.6 times higher than the Ti6Al4V substrate. Meanwhile, the corrosion resistance and wear resistance of the Ti/TiBCN composite laser clad coating is much superior to that of the Ti6Al4V substrate, where the wear mechanism of coating was abrasive.
Keywords: Fibre laser, titanium alloy, Ti6Al4V, Ti/TiBCN composite coatings, laser cladding, microstructure, microhardness, corrosion resistance, wear resistance