Study of the Incorporation of SiC Microfibers and Their Effect on Adherence at the Interface of a NiCoCrAlY-7YSZ Thermal Barrier Coating

The present work studied the effect of the addition of SiC microfibers and their influence on interfacial adherence of NiCoCrAlY-7YSZ thermal barrier coatings (TBCs) systems. Two different coatings were fabricated (with and without the addition of SiC microfibers) and exposed to isothermal oxidation heat treatments (OHT) at 950 °C from 50 to 200 h. The microstructure and pull-off test evaluations showed that coatings reinforced with SiC possess a thinner thermally grown oxide (TGO) layer, suggesting an improvement in the oxidation resistance of these samples. In this sense, the coating with SiC also displayed better adherence resistance after 50 and 200 h of exposure. On the other hand, after the pull-off tests, reinforced samples showed a lower percentage of fracture. The above indicates that SiC microfibers enhance the interfacial adherence between the TGO and the ceramic layer (TC) by forming complex oxides resulting from the self-healing reaction mechanism.