Microstructure and friction coefficient of ceramic (TiC, TiN and B4C) reinforced Ni-based coating by laser cladding

Abstract

Ni204 ceramic composite coatings with different mass fractions of TiC, TiN and B4C were successfully prepared on the surface of 45 steel by laser cladding. Microstructures of different ceramic coatings were studied using X-ray diffraction, scanning electron microscopy and laser confocal microscopy. The friction coefficient and microhardness of ceramic coatings were measured with a reciprocating friction wear machine and microhardness tester. The results show that ceramic coating has 766.8HV0.5 average microhardness and friction coefficient of 0.47 when 10%TiC, TiN, and B4C are added to initial powder Ni204. The microstructure of cladding layer is uniform and compact, and the microhardness and friction coefficient of the coating increased and decreased by factors 2.6 and 1.393 compared with initial powder. This is due to the presence of multiple phase ((Ti, Mo, Nb) (C, B, N)), carbide, nitride, (Ti, Mo, Nb) (C, B, N), and (Ti, Mo, Nb) (C, N) ring phase around TiC, TiN, and Ti(C, N) ceramic phases. Uniformly distributed reinforced phases in the coating inhibit extrusion by grinding balls on the surface of the ceramic coating, thus changing original abrasive wear mechanism, making wear marks more shallow, and decreasing friction coefficient of the surface.