Microstructure Characteristics and Properties of HVOF Sprayed Ni-Based Alloy Nano-h-BN Self-Lubricating Composite Coatings

A Ni-based alloy/nano-h-BN self-lubricating composite coating was produced on medium carbon steel by high velocity oxygen fuel (HVOF) spraying technique. The powder feedstocks for HVOF spraying were prepared by ball milling and agglomerated the nano-h-BN with Ni-based alloy powders. The microstructure and mechanical properties of coatings have been investigated. With the increasing of h-BN contents, some delaminations appeared gradually in the coatings and a continuous network with h-BN phase embedded formed in the metallic matrix. The average microhardness of the self-lubricating coating was a little lower for the addition of soft solid lubricant. The friction coefficient of coatings is in the ranges of 0.38-0.48 and 0.38-0.52 at ambient temperature and 400 degrees C, respectively. The maximum bonding strength of coatings reached 23.83MPa.