Effect of Preheating Temperature on the Microstructure and Corrosion Resistance of TiC–Ni Coating by CS/PHIP

Abstract

TiC–Ni composite coatings with different preheating temperatures were fabricated in situ on the H13 steel substrate by combustion synthesis combined with pseudo-heat isostatic press. The effects of preheating temperature on microstructure, surface porosity, mechanical properties and corrosion behaviour were investigated. The coatings were characterized by XRD, SEM–EDS and microhardness tester. The in situ composite coatings prepared at different preheating temperatures consisted of a network of Ni binder phase (white) and a spheroidal TiC phase (dark) embedded therein. The grain size of TiC, the proportion of the TiC-reinforced phase, surface hardness and interfacial bonding strength increased with increasing preheating temperature. The density and dimension of the AlNi3 phase after the immersion test decreased with an increase in preheating temperature. The corrosion mechanism of the coating was that the Ni binder phase was corroded by aluminium and the TiC phase got oxidized.