High-Temperature Oxidation Effect on High-Velocity Oxygen Liquid Fuel and Laser-Remelted High-Velocity Oxygen Liquid Fuel MCrAlY Coatings

MCrAlY coatings are widely used in high-temperature applications against oxidation and corrosion. Under high-temperature conditions, selective alumina formation which provides higher resistance to oxygen penetration is possible using the MCrAlY coatings. Metallic MCrAlY alloys can be produced by many coating techniques. The produced coatings can also be modified using surface treatments. In the present study, CoNiCrAlY was deposited on a 316L stainless steel (S.S.) substrate using the high-velocity oxygen liquid fuel (HVOLF) technique. The deposited coating was subjected to a laser surface remelting process. The remelted and as-sprayed CoNiCrAlY coatings were subjected to isothermal oxidation tests for 5, 25 and 50 h at 1050 °C. The produced and oxidized samples were characterized using scanning electron microscopy (SEM), SEM line and elemental mapping analysis, x-ray diffractometer, and Image-Pro Plus 6 software program. After the examination of oxidized samples, the laser-remelted coating exhibited superior oxidation resistance compared to the as-sprayed coating due to the eliminated porosities beneath the surface regions and the formation of the alpha alumina layer.