Scratch Resistance of NiTi Atmospheric Plasma Sprayed Coating

Abstract

In this research, the elemental composition of Ni50Ti50 has been taken to coat a structural steel substrate at different substrate preheating temperatures (100, 200, 300, and 400 ℃). Homogenized NiTi powder has been sprayed using an atmospheric plasma spraying technique. After coating, the surface and interface properties were analysed by X-Ray diffractometer (XRD), scanning electron microscopy (SEM), and scratch tester. The scratch resistance of NiTi plasma spray coatings was assessed under constant and variable loads. Again, the surface morphology of the scratch track was investigated by SEM. The scratch resistance shows the effect of shape memory behaviours, which is the novelty of this investigation. The principal mechanism of failure of the coatings was plastic deformation, tensile cracking, and spallation. NiTi and their intermetallic (such as Ni4Ti3, Ni3Ti, and TiO2) play important role form dense splat formation and higher hardness. At 400°C preheating temperature coating shows higher cohesive bond strength as compared to lower preheating temperature due to better mechanical bonding between the splat at higher preheating temperature.