Deposition and characterization of Al-Si metallic TBC precursor on Mo-Si-B turbine materials

摘要

The interfacial reactions of Mo-Si-B with Al-Si metallic coatings during processing to achieve high-temperature corrosion protective mullite coating for advanced turbine materials are discussed. Al-Si is being deposited on the Mo-Si-B substrate material by immersion in liquid Al-Si alloy, molten salt cathodic deposition, and organic electrolysis, to achieve adhesion and compositional gradients across the interfacial region. The interfacial region during Al-Si deposition is the precursor to the formation of compositionally graded mullite by annealing and subsequent oxidation. The optimum Al-Si content of this metallic layer, which will be attained by deposition combined with silicon diffusion from Mo-Si-B, is described. Characterization of the constitution and gradients across the interfacial region is reported. Transport modeling in this precursor layer and the substrate is discussed.