Preheating treatment of thermal barrier coatings by supersonic plasma jet

The low thermal cycling life is a big concern for plasma sprayed thermal barrier coatings (TBCs). This paper presents a novel and effective preheating treatment conducted by one supersonic plasma jet, which has been proven to significantly improve the anti-oxidation and thermal shock resistance of TBCs. After preheating treatment, the surface roughness (Ra) of metallic bond coat decreased by nearly 30%, while one dense oxide layer appeared on its surface. This oxide layer effectively suppressed the growth of thermally grown oxides (TGOs), resulted in the improvement of anti-oxidation of TBCs. The results of water-quenching test from 1100 °C into room temperature showed that the thermal cycling life of preheated TBCs reached 846 cycles, approximately 126 cycles higher than their counterparts without preheating.