Thermal Shock Resistance Behaviour of Multilayered Gd2O3 Doped YSZ on Inconel-718 Substrate

Inconel 718 is a Nickel-based super alloy which is used in the high temperature sections of gas turbine engines in the aerospace industry due to its corrosion resistance and strength at high temperatures. Further improvements of properties are achieved by applying thermal barrier coatings on the material. NiCrAly is sprayed as the bond coat over the substrate for a thickness of 100 mu m. After the bond coating, pure YSZ, mixture of YSZ and Gd2O3 powder prepared by ball milling process with various proportions are plasma sprayed on the substrate over the bond coat with a thickness of 300 mu m which acts as the top coat. Similarly for multi layer coating, a sequence of bond coat, pure YSZ, combinations of Gd2O3 and YSZ and finally pure YSZ is sprayed over the substrate with thickness of 100 mu m each. Thermal shock test was conducted on the coated to study the optimum composition of coating and the layer arrangement of coatings which can withstand the high temperature shock. In this all the specimens withstood the thermal cyclic test and the higher concentration of Gadolinium oxide in YSZ as an intermediate layer failed at 440 cycles. (C) 2019 Elsevier Ltd. All rights reserved.