Mechanical performance of plasma-sprayed bulk-like NiCrMo coating with a novel shell-core-structured NiCr-Mo particle

In this study, novel heat-treated shell-core-structured (SCS) NiCr-23Mo powder is employed to realize the deposition of a bulk-like metallic coating with excellent mechanical performance by plasma spraying. The SCS NiCr-23Mo powder was fabricated by cladding spherical Ni20Cr particles with refractory Mo as an alloying element. This ensures the generation of ultra-high temperature Ni16Cr23Mo droplets during the in-flight process of plasma spraying. The interface bonding between the Ni16Cr23Mo single splats and steel substrate, as well as the microstructure of the Ni16Cr23Mo coating were characterized. Mechanical behavior of the coating was examined by erosion test. Results showed that the Ni16Cr23Mo coating exhibited a dense microstructure with significantly improved adhesive strength. Moreover, effective bonding was formed at 78% of interfaces between the Ni16Cr23Mo splat and steel substrate, which was much higher than the 36% of the conventional NiCr splat. Erosion test revealed that the Ni16Cr23Mo coating presented excellent erosion resistance, being comparable to that of the Ni-based bulk alloy. Moreover, the Ni16Cr23Mo coating presents ductile mechanical behavior during erosion test rather than the brittle behavior of the conventional Ni-based alloy coating. Thus, a mechanically bulk-like coating with excellent interface bonding and excellent erosion resistance can be achieved by plasma spraying of the novel SCS NiCr-23Mo powder.