Superior oxidation and spallation resistant NiCoCrAlY bond coat via homogenizing the yttrium distribution

摘要

We present a novel approach to significantly improve the oxidation and spallation resistance of a NiCoCrAlY bond coat by homogenizing the yttrium distribution via powder milling and subsequent spark plasma sintering. The NiCoCrAlY bond coat fabricated by this method exhibits a much lower oxidation rate and a significantly better spallation resistance after isothermal oxidation at 1150 degrees C, compared with the counterpart fabricated from the un-milled powder. To understand the improvement in oxidation resistance, the microstructure of the bond coats, the chemistry and microstructure of the thermally grown oxides (TGOs), the TGO stresses and the interfacial chemistry are systemically investigated.