Halogen plasma erosion resistance of rare earth oxide films deposited on plasma sprayed alumina coating by aerosol deposition

Dense yttria, erbia and dysprosia films with thicknesses of 44.8 ± 1.7, 51.6 ± 0.9 and 36.8 ± 3.1 μm, respectively, were deposited on plasma sprayed alumina coating by aerosol deposition (AD). The rare earth oxide films remarkably enhanced the erosion resistance of the plasma sprayed alumina coating upon exposure to the halogen gas plasma. The enhanced plasma erosion resistances were related to their low surface porosity as well as the low vapor pressures of the rare earth fluorides and chlorides compared with those of corresponding aluminum halogenides. Electrical breakdown voltages of the samples with yttria, erbia and dysprosia films on the plasma sprayed alumina coating were 5.5, 6.2 and 5.3 kV, respectively, at room temperature and 4.0, 4.2 and 3.9 kV, respectively, at 573 K. The breakdown voltages at RT and 573 K were more than double that of the plasma sprayed alumina coating without the AD films.