Thermal plasma spraying of NiTi powder for thick coating of shape memory alloy

Abstract

In this article, NiTi coating was fabricated via a thermal plasma process by tuning various parameters. The work aims to achieve shape memory behavior that could retained in the plasma-sprayed samples. Various plasma spraying process parameters such as plasma power, powder feed rate, spraying plan, and net powder spray were taken into consideration for the spraying. Microstructural, thermal, mechanical, and shape memory behavior was analyzed on the plasma-sprayed samples. Various phases austenite, martensite, and intermetallic phases such as NixTiy, Ni-Ti-O, Ni, and Ti were confirmed from the X-ray diffraction analysis. The presence of these phases in the samples contributes to the thermal transformation and mechanical behavior. A less heat-affected zone of 10 µm along the interface was confirmed without any diffusion of elements from the substrate to the coating layers. There was a homogenous distribution elemental composition of Ni and Ti throughout the coating layers. The shape memory behavior of the coating samples was confirmed by the thermo-mechanical analysis by performing the response in multiple cycles.