Effect of Pt content on initial TGO formation and available Al reserve of Pt-Al coatings during thermal cycling

Platinum aluminide coatings with different Pt content were fabricated. Their oxidation kinetics and the growth behavior of TGO were investigated. By analyzing the effect of Pt content on the oxidation rate constant and the surface roughness, we found that 13.92–18.52at.% Pt addition promoted the formation of TGO, and the coatings with ≤13.92at.% Pt addition showed relatively low surface roughness. However, the mechanically induced chemical failure occurred on the coating with high Pt content (≥26.96at.%) due to the decreased Al reserve. Our results indicated that the optimum Pt content was 13.92at.% and excessive Pt addition decreased Al supplement of coatings for TGO sustainable growth.