Performance of the glass-ceramic coating prepared by slurry spraying technique

摘要

The SiO_2-BaO-CaO-MgO-ZnO glass-ceramic (GC) coating was prepared on the surface of the nickel based alloy GH140 by slurry spraying technique. Morphology, phase and elemental composition of the glass-ceramic before or after isothermal oxidation for 96 h at 1000°C were investigated by SEM, XRD and EDX. Results showed that the glass-ceramic was mainly composed of BaSiO_4 and MgCrO_4, and the amount of them both increased after being oxidized for 96 h. Compared with bare GH140, GC/GH140 presented a pretty good antioxidant capacity. Before oxidation, white elongated crystals were homogeneously distributed in the glass phases, and a thin transitional layer had already been formed between glass-ceramic and substrate. During the oxidation process, the surface morphology of GC/GH140 became coarse, and small black Si-rich crystals appeared and well-distributed in the coating. Meanwhile, Cr and Ti in the substrate diffused to the interface, which lead to the formation of an oxide-rich interface that protected the substrate from further oxidation.