Performance Characteristics of Thermal Barrier Coatings: A Case Study

Degradation of hot section components in the turbine section of gas turbines used in the power generation industry can cause significant problems including financial penalties associated with down time and a decrease in operating efficiency. High temperature oxidation and hot corrosion can cause severe material loss. The use of thermal barrier coatings to mitigate such factors is becoming increasingly common and has been used for many years in land-based gas turbines. However, the experience of equipment users has had limited publicity. The purpose of this paper is to share some of the experiences of a large integrated power company and an independent service provider of turbomachinery refurbishment. A variety of thermal barrier coatings from a few selected vendors were run in a rainbow test over a two year period. Inspections of the stationary nozzle segments were carried out after the first and second year. The findings regarding the performance of the coatings are discussed within. Differences between the coatings application processes, the coating raw material, the vendors and location of part in the nozzle are discussed.