Investigation on the performance of air plasma sprayed thermal barrier coating with Lu/Hf-doped NiAl bond coat

The durability of air plasma sprayed (APS) thermal barrier coatings (TBCs) with NiAl bond coats with/without Lu/Hf doping was investigated under thermal cycling at 1150 °C, and compared with the conventional NiCoCrAlY sample. The oxidation kinetics, microstructure evolution and surface roughness of the bond coats were characterized and the cycle lifetime measured. The TBC with the NiAl bond coat exhibited a lifetime of 456 h, which was comparable with the NiCoCrAlY sample (480 h). By contrast, the NiAl-Lu/Hf TBC showed a two or three fold enhanced lifetime, i.e., 840 h and 1248 h, respectively. It is proposed that the enhanced lifetime is a result of combination of decreasing of the oxidation rate and retention of the interfacial toughness. The APS NiAl bond coat with Lu/Hf doping has a great potential for TBCs designed for higher temperature applications.