料浆喷涂微晶玻璃涂层的微观组织结构及其抗氧化性能

Microstructure,phase composition and oxidation resistance of glass-ceramic coating prepared by slurry spraying technique

采用料浆喷涂法在镍合金GH140基体上制备SiO2-BaO-MgO-ZnO微晶玻璃涂层,研究微晶玻璃涂层在高温下的抗恒温氧化性能。通过SEM,EDS和XRD分析GC/GH140晶化处理及1 000℃恒温氧化前后的形貌特征、相组成以及元素分布的变化。研究结果表明:GC/GH140氧化质量增加极小。晶化热处理前,微晶玻璃涂层与GH140基体结合致密,在涂层烧结过程中,基体中的Cr和Ti向涂层界面扩散,形成富Cr和Ti致密氧化膜,并在基体中形成了一层很薄的氧化物不连续分布的过渡区域。晶化热处理2 h后,涂层中析出主要成分为白色柱状BaSi4O9和黑色SiO2颗粒,氧化膜与过渡层的厚度变化不大。随恒温氧化时间延长,涂层的相组成保持不变,黑色SiO2相含量迅速增加,过渡层厚度缓慢增加;氧化96 h后,涂层与基体仍然结合良好,表面也十分致密,有效阻碍了氧的扩散,大幅度提高了基体的抗氧化能力。

The SiO2-BaO-CaO-MgO-ZnO glass-ceramic coating was prepared on the surface of the nickel based alloy GH140 by slurry spraying technique, and was oxidized isothermally at 1 000℃ for 96 h. Morphology, phase and elemental composition of the glass-ceramic were investigated through SEM, XRD and EDX. The results show that the glass coating is impervious before crystallization heat treatment when there appears an oxide-rich interface and a thin transitional layer where the oxides are discontinuously distributed, and after crystallization for 2 h, major phases of white elongated shape BaSi4O9 are precipitated and accompanied with SiO2, which increases and is homogeneously distributed with the increase of oxidation time. Meanwhile, the thickness of the transitional layer increases a little. GC/GH140 presents a pretty much low oxidative rate. With being oxidized for 96 h, the glass-ceramic combines well with GH140 and keeps an impervious surface morphology that prevents the oxygen from being diffused into GH140, all of which proves the excellent oxidation resistance of glass-ceramic.