Microstructure and Hardness of NbC Coating Produced In Situ

Abstract

The niobium carbide (NbC) coating on gray cast iron has been produced by in situ which combined infiltration casting and heat treatment. The microstructural observations of the coating have been obtained by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). And the growth mechanism of NbC grain was studied. The results show that the mechanism is orientation connection which means two particles of the same lattice orientation will be directly connected together and oriented attachment growth. Fine NbC grain can improve the nanohardness value of the coating with 23 GPa, meanwhile, it increase the elastic modulus with the value of 493.7 GPa.