Mechanical and nanoindentation behavior of TiC–NiTi thermal spray coatings

The nanoindentation behavior of wear resistant coatings containing TiC–NiTi is studied. The raw material contained 60% weight of TiC and 40% weight of near equiatomic NiTi. The powder was sprayed by plasma and HVOF techniques. Higher temperatures in the plasma spraying produced better matrix melting but also more cracks on cooling. The presence of some amorphous or nanocrystalline phase occurs, at least in some coatings, being this related to the good wear behavior. The projection conditions play an important role on the partial transformation because of the decomposition and oxidation of the NiTi as a consequence of the temperatures involved during the spray deposition. The nanoindentation measures suggest that, even with the presence of hard TiC particles, partial oxidation and dissociation of NiTi, there is some pseudoelasticity.

► Wear resistant NiTi–TiC coatings obtained by HVOF and plasma spraying techniques. ► Presence of amorphous phase and partial dissociation of NiTi matrix. ► High recoverability of nanoindentation and pop-ins suggest partial martensitic transformation in NiTi matrix.