Wear resistant self-healing tribological surfaces by using hard coatings on NiTi shape memory alloys

Shape memory materials are among several smart materials being investigated for a wide range of applications, including “self-healing” tribological surfaces. Although shape memory alloys have recently been demonstrated as self-healing tribological surfaces, the wear resistance of the shape memory materials alone is usually not as good as conventional hard coatings. In this paper, the synergetic effects of combining hard coatings with shape memory alloys as wear resistant self-healing tribological surfaces are explored. Specifically, the wear resistance and shape recovery ability of uncoated and CrN coated NiTi alloys are investigated using pin-on-disc, indentation and scratch test. It is found that CrN hard coating can significantly improve the wear resistance of the NiTi shape memory alloy while maintaining its shape recovery ability. This example demonstrates that hard coatings on shape memory alloys can be used as wear resistant self-healing surfaces for tribological applications.