Aluminide Coating Simulations

2016-08-01
Boyraz, Mustafa Tarık
İmer, Muhsine Bilge
Nickel-based super alloys are generally preferred as substrate materials for gas turbine blades due to their high creep resistance and excellent mechanical strength at high temperatures. To improve high temperature oxidation and corrosion resistance ofthese substrate materials, aluminide coatings are typically used as protective coatings, thereby improving lifetimes of advanced gas turbine blades. For clean and pure coating of aluminum at substrate surface, chemical vapor deposition method (CVD) is widely used for turbine blade coatings. The aim of this research is to develop a simulation model using DICTRA that is compatible with experimental CVD operations. After this aim is achieved, the ultimate goal is to use this simulation model to provide input parameters for experimental CVD operations. In this research, two models were compared and named as “Diffusion Couple Model” and “Al Deposition Model”. The “Diffusion Couple Model” simulates diffusion between IN 738LC and Al diffusion couple while the “Al Deposition Model” simulates surface growth and interfacial diffusion during Al deposition. Coating thickness, composition and phase profile results of both models were compared with experimental results, and most compatible model was determined. Using the model with best compatibility, effect of CVD operation time, temperature and deposition rate were investigated using DICTRA software. Main criteria were to create a pure and uniform β-NiAl zone with high Al content (35-55 %at.), and to maximize β-NiAl to interdiffusion zone thickness ratio to improve the lifetime and mechanical properties of IN 738 LC turbine blades. After the simulations were completed, results were compared with experimental CVD results and simulation model was modified to carry out more compatible results with real life CVD operations.
Citation Formats
M. T. Boyraz and M. B. İmer, “Aluminide Coating Simulations,” presented at the 3rd International Conference OnThermophysical And MechanicalProperties OfAdvancedMaterials (THERMAM 2016), 1 –3 SEPTEMBER 2016, Izmir, Turkey, 2016, Accessed: 00, 2021. [Online]. Available: https://hdl.handle.net/11511/86166.