Thermal barrier coatings for enhanced efficiency of gas turbine engines

In the current paper, an attempt has been made to address the benefit as well as importance of optimisation of thermal barrier coatings system for super alloys after evaluating different thicknesses of ceramic thermal barrier coatings. The thickness of coatings plays a major role in deciding the life of coatings as lower thickness does not provide complete protection and higher thickness causes to reduce the coating life due to adherence problems. Therefore, determination of optimum thickness to obtain improved performance is highly essential. An optimum thickness of thermal barrier coatings has been determined successfully by conducting hot corrosion studies on various thicknesses. The optimised protective coating system enhances the life of super alloy by about six hundred times. The optimum performance of the designed coating system is due to the formation of a continuous and protective layer of a combined alumina and chromia scales. Based on the results, a degradation mechanism is proposed and showed that the protective properties of ceramic coatings are lost due to chemical reactions taking place under hot corrosion conditions. Finally, the necessity of application of optimum thick thermal barrier coatings with compositionally optimised NiCoCrAlY coating, which can protect the gas turbine engine blade materials significantly against both oxidation and hot corrosion conditions, is emphasized. (c) 2006 Elsevier B.V. All rights reserved.