Under the optimized laser process parameters, the cermet composite coating was successfully prepared on the surface of Ti–6Al–4V alloy with different mass fractions of NiCrBSi, TiN and BN alloy powders. The TiN reinforcing phase and the BN lubricating phase in the coating mainly exist in the form of black particles which are coated by a coating to form a core–shell structure. With the BN mass fraction increases, black particles aggregate into new dendritic structures.
During the laser cladding process, part of TiN and BN are decomposed and recombined under the action of laser. Uniform distribution of TiN reinforcing phase and BN lubricating phase, which is of great significance to improve the wear resistance of the coating.
The microhardness of the composite coating is obviously improved compared with that of the matrix. When the BN mass fraction is 5%, the average microhardness of the coating reaches 967.1 HV. This is mainly due to the convection of the molten pool during laser cladding, and the decomposition of Ti atoms and N atoms in the matrix to forming a large amount of dispersed distribution of TiN reinforcing phase in situ.
Dry friction and wear tests at room temperature show that the wear resistance of the composite coating is significantly improved compared to the Ti–6Al–4V substrate. When the BN mass fraction is 5%, the coating friction coefficient is about 0.35, and the wear resistance is 2.6 times higher than that of the substrate.
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