Investigation of hot corrosion and oxi̇dati̇on behaviour of thermal barrier coatings

Thermal barrier coatings (TBCs) are finding increasing application (in the most demanding) high-temperature environment of aircraft and industrial engines. They have the capability to improve the durability of engines by reducing the surface temperature of the underlying components. The use of TBCs, along with internal cooling of the underlying super alloy components, enabled advanced gas turbine engines to operate at temperatures even above the melting temperature of the super alloy, with achieving a remarkable increase in the efficiency and performance of engines. This technology has been regarded to improve as one of the most important and effective developments in the propulsion efficiency of advanced aero engines. Thermal barrier coatings (TBCs) are widely used on supper alloy substrate typically consist of a metallic MCrAlY bond coat to protect substrate from oxidation, thermal insulating ceramic top coat and thermally grown oxide layer (TGO) at the interface of ceramic top coat and metallic bond coat. In thermal barrier systems Yittria stabilized zirconia (YSZ) is most commonly used for thermal insulating ceramic top coat because of its low thermal conductivity and high thermal expansion coefficient. TBCs are applied to provide thermal insulating to the hot section components of gas turbine in an attempt to preserve them from thermal deterioration and to improve the performance and operating temperature of the engine. The coatings powders are mixed in the compositions of wt% YSZ-35-50-65- wt % Al2O3 The mixtures are milled along 3h in alcohol to provide homogenous mixture and kilns dry more 4h. The substrates were applied grit blasting and cleaned by using alcohol before depositing. Bond coat was fabricated by using high velocity oxygen and fuel (HVOF) and the ceramic top coat was fabricated using plasma spray method (PS) Keywords: Thermal barrier coatings, oxidation and hot corrosion behavior of TBCs, plasma spray coating, ZrO2 and Al2O3 coating