Effect of the top coat on the phase transformation of thermally grown oxide in thermal barrier coatings

The phase transformation of the thermally grown oxide (TGO) formed on a Pt enriched γ + γ′ bond coat in electron beam physical vapour deposited thermal barrier coatings (TBCs) was studied by photo-stimulated luminescence spectroscopy. The presence of the TBC retards the θ to α transformation of the TGO and leads to a higher oxidation rate. The reasons for these phenomena are discussed.