Effects of post-deposition heat treatment on the microstructure and dry sliding wear behavior of cold-sprayed Ni/CrC-NiCr composite

The effects of various post-spray heat treatments on the microstructure and tribological behavior of cold-sprayed Ni/CrC-NiCr metal matrix composite (MMC) coatings were investigated. The heat treatments (HTs) included annealing at two different temperatures by laser heating (LH), and plasma arc heating (PAH). The effects of these HTs on wear resistance, hardness, and microstructural evolution were systematically analyzed. Scanning Electron Microscopy (SEM), and X-ray Diffraction (XRD) were employed to examine wear track morphology, subsurface microstructure, phase composition, and chemical analysis of the tribolayer and mechanically modified layer. Optical profilometry was also used to characterize the dimensions of the wear track. The results demonstrated that annealing improved the interparticle (IP) and inter-splat (IS) bonding ratios, but led to matrix softening and void formation, resulting in increased specific wear rates. In contrast, LH and PAH resulted in IP and IS bonding ratios similar to the as-sprayed coating, and the formation of thin oxide tribo-films significantly reduced the specific wear rates by over 50% compared to as-sprayed coatings. The average friction coefficient for all heat treatments remained relatively constant at ∼0.65.