在镍基高温合金K38G基体上制备了双层搪瓷-陶瓷复合涂层, 其中面层为搪瓷-50 mass%石英, 底层为搪瓷-50 mass%刚玉层. 涂层结合力良好, 表面均匀致密, 有釉面光泽. 1000℃、120 h氧化结果表明, 涂层试样的氧化增重仅为0.2 mg/cm2左右, 比文献中报道的NiCrAlY涂层的氧化速率低数倍(Ni-22Cr-10Al-1Y(mass%) 1000℃ 100 h氧化增重已达1.2 mg/cm2). 刚制备出的搪瓷-陶瓷复合涂层中的部分石英颗粒已转变为方石英相, 并析出少量的锆英石相和钠长石相. 氧化后的涂层中大部分石英颗粒转变成方石英, 并析出少量的钾长石相. 氧化后的涂层试样中Ni, Cr富集分别出现在涂层的外层靠近空气区域和内层靠近外层区域, 而氧化前后内层靠近基体区域都有Ni, Cr, Al富集.
A bilayered enamel-ceramic composite coating, consisted of an inner layer of enamel-50 mass % corundum and an outer layer of enamel-50 mass % quartz, was prepared on nickel-based superalloy K38G by spray-sintering technique. The coating is dense with glaze surface and has good adhesion to the substrate. Its oxidation behavior at 1000℃ for 120 h was studied by means of thermogravimetry, SEM, EDS and XRD. Cristobalite, a high-temperature polymorph of quartz, and zircon and albite precipitates were detected in the as-prepared enamel-ceramic composite coating. In addition, Ni, Co and Cr were present in the inner layer of enamel-corundum. The mass gain of the coated alloy after 120 h oxidation was about 0.2 mg/cm2, quite lower than those of NiCrAlY coatings. Most of the quartz particles in the coating transformed into cristobalite after oxidation tests. Besides, orthoclase was detected too. Ni-enrichment was observed in the outermost region of the outer layer, while Cr-enrichment was found in the inner layer close to the inner/outer interface. And Ni-, Cr-, Al-enrichment were found in the inner layer near the substrate either of the as-prepared samples or of the samples after oxidation tests.
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