材料期刊网

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-50mass％石英，底层为搪瓷-50mass％刚玉层．涂层结合力良好，表面均匀致密，有釉面光泽．1000℃、120h氧化结果表明，涂层试样的氧化增重仅为0．2mg／cm^2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℃100h氧化增重已达1．2mg／cm^2）．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 NiCrA1Y coatings. Most of the quartz particles in the coating transformed into cristobalite after oxidation tests. Besides, orthoelase 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.