Werner Stamm

MCrAlY Coatings for Gas Turbine Blades Life Time Estimation Based on the Diffusion-Controlled Processes Modelling

Calculational and experimental approach was developed for life time analysis of MCrAlY coatings for industrial gas turbine blades. This approach based on the model that describes the main diffusion and oxidation processes within the coating-base metal system as well as the experimental data for specimens after different short time exposures at different temperatures. In comparison with existing models the proposed model describes interdiffusion zone between coating and base alloy. The models adequacy to physical processes is provided by model parameters identification with short-time experiment data for coating – base alloy systems. The measured Al concentration profiles were used as input values for the model parameters estimation and a calculational prediction of the long term diffusion and oxidation behaviour of the coating was performed. The model, calculational and experimental approach as well as MCrAlY life time estimation results for 10000 h at 950°C are presented. These results were obtained with short time experimental data for Al concentration profiles across the coating thickness measured after 300 and 1000 h. The predicted and measured b-phase content at coating during oxidation for coating thickness 200 micron at 900, 950 and 1000 °C are presented too. The b-phase content disappear at coating was assumed as a corrosion life time criterium.