Wear properties of functionally gradient layers on stainless steel substrates for high temperature applications

Metal substrate components have been coated with functionally gradient coatings (FGCs) to improve thermal barrier properties and heat efficiency of high temperature materials in gas turbine engines, nuclear fusion equipment, diesel engines, jet engines and space shuttles. In this study, functionally graded materials (FGMs), which contain NiCrAl, 75% NiCrAl + 25% MgZrO₃, 50% NiCrAl + 50% MgZrO₃, 25% NiCrAl + 75% MgZrO₃ and 100% MgZrO₃ coating layers, have been produced onto stainless steel substrates via an atmospheric plasma-spray technique. The fabricated samples were characterized by means of an optical microscope, scanning electron microscope (SEM), X-ray diffraction and microhardness tester. The wear behaviour of the FGCs was evaluated under dry conditions using a pin-on-plate configuration. The surface morphologies of the FGM samples after wear experiments were examined by SEM. The wear mechanism of the FGCs is discussed based on SEM observation of the worn surface morphologies.