Surface/Interface behaviour of atmospheric plasma sprayed NiTi alloy on stainless steel with the variation of critical plasma spray parameter

NiTi equiatomic composition is used in atmospheric plasma spraying (APS) machine to coat the stainless steel substrate. APS was conducted with varying critical plasma spraying parameters (CPSP) using NiTi powder as a coating element. After coating, the surface and interface morphology were characterised by XRD, SEM, and hardness tester. Higher CPSP yields better surface morphology. Surface roughness and porosity percentage decrease, and hardness increases from (455–844) Vickers hardness number with CPSP. The residual stress varies from 73 ± 1.1 MPa to −95 ± 1.9 MPa which shows the stress conversion of coating from tensile to compressive with an increase in CPSP. Coating failure occurs as a combined result of adhesion, cohesion and glue joint failure. At 865 CPSP, coating shows highest adhesion strength 42.13 MPa.