The Effect of Top Coat on Hot Corrosion and Oxidation Protection of TBC in Gas Turbine Blades

Thermal barrier coatings (TBC) not ony limit heat transfer through the coating, but also protect gas turbine hot components from oxidation and hot corrosion. No single coating composition appears to be able to satisfy the muhi:functional requirements. As a result, a ''multilayer coating systems" has developed. Researches in the last 20 years has led to a preferred coating system consisting of three separate layers achieving long term effectiveness in the high temperature, oxidative and corrosive use environment. In this paper, hot corrosion and oxidation properties of top coat TBes were studied. For this purpose, samples were prepared from new fabricated blades and then furnace hot corrosion and oxidation on samples were performed. The map of element and thickness of coating measured by the scanning electron microscopy (SEM) and weight loss of corroded samples by used balance, on samples with or without a top coat were determined. The resuhs appeared; the top coat improved corrosion and the oxidation protection ofTBCs coatings.