Microstructure and Properties of CoCrNi/Nano-TiC/Micro-TiB2 Composite Coatings Prepared via Laser Cladding

Laser cladding was used to prepare CoCrNi-xTiC-xTiB2 (x = 0, 5, 15 wt.%) composite coatings on 316L stainless steel. Then, ceramic mass fraction effects on the microstructure and properties were investigated. Results show viable metallurgical bonding between the coating and the substrate, with no apparent pores or cracks. The addition of ceramics transformed the coating phase from a single-phase face-centered cubic (FCC) to a multi-phase FCC+TiC+TiB2. TiC and TiB2 increased the hardness of the CoCrNi-xTiC-xTiB2 coating from 209.71 HV to 494.77 HV by grain refinement and diffusion strengthening. The substrate wear loss was 0.0088 g, whereas the CoCrNi-xTiC-xTiB2 (x = 15%) coating wear loss was only 0.0012 g. Moreover, the overall wear mechanism of the coating was changed: the substrate wear mechanism was used for abrasive wear, adhesive wear and fatigue wear, and the coating with the addition of 15 wt.% nano-TiC and 15 wt.% micro-TiB2 was the wear mechanism for pitting fatigue wear.