Investigation & characterization of plasma sprayed cermet coatings on special steel alloy for gas turbine applications

Abstract

Abstract The gas turbines are the components which are commonly affected by severe high-temperature erosion wear due to impingement of solid particles entrained in the stream of fluid. The present investigation focuses on the applicability of plasma sprayed coatings for turbines by improving the erosion resistance of the base material. The present work includes high-temperature solid particle erosion behaviour of [35%(WC-Co)/65%(Cr3C2NiCr), [70%NiCrAlY\xa0+\xa030%TiO2] & [70%NiCrAlY\xa0+\xa025%Cr2O3\xa0+\xa05%YSZ] coatings deposited by atmospheric plasma spray (APS) process. All the coating materials are considered by weight (%). The effect of impact angle on erosion performance of uncoated and coated specimens were comparatively studied by using the air-jet erosion tester (ASTM G76-13). The eroded surface morphology was analysed by using a porosity tests, microhardness values, scanning electron microscopy & X-ray diffraction analysis. All Coatings exhibits the ductile erosive mechanism at the temperature of 700\xa0°C with severe plastic deformation. The NiCrAlY\xa0+\xa0TiO2 coating is more protective than the other two coatings in high temperature and erosion environments due to its higher ductility, homogenous microstructure, and lesser porosity of the coatings. However, uncoated MDN 420 steel exhibits lesser wear loss when compared to the coated substrates. This may be due to the alumina particles embedment onto the coated surface, which might present a shielding effect against further material loss to occur.