Coating requirements in gas turbine engines

Abstract

The complex thermal, chemical, and mechanical environment of the gas turbine engine makes it extremely difficult for one material to meet all of the different requirements imposed on the various engine components. Coatings are thus required to provide corrosion, resistance, wear resistance, insulation, and abradability. In the turbine section of the engine, in particular, the overall operating conditions are becoming progressively more hostile in terms of temperature and mechanical environment as engine efficiency and performance are improved. In certain types of operation the corrosive environment is emphasized. Thus, coatings must provide increasing protection, the need for which is often aggravated by the limitations which considerations such as strength requirements may place on the inherent environmental resistance of the base material. Perceived future coating needs are discussed. It is probably only in the last decade that coating requirements, in terms of application and behavior, have been recognized as an essential aspect of the design process. Significant future work remains to be done and this aspect is also discussed.