SiO_2-BaO-Al_2O_3-Cr_2O_3陶瓷保护涂层的制备及性能

Preparation and Performance of SiO_2-BaO-Al_2O_3-Cr_2O_3 Ceramic Protective Coating on Austenitis Stainless Steel

为提高奥氏体不锈钢抗高温氧化及化学侵蚀能力,确立了以SiO2-BaO-Al2O3-Cr2O3为主要化学组成的氧化物陶瓷涂层体系,并对涂层的制备工艺进行了探讨。涂层制备工艺:研磨后的涂层粉体平均粒径Dsv为1.52μm,95%粉体粒径(D95)小于3.40μm;以水作为分散介质制备涂层料浆,料浆的福特杯黏度为12～16 s;不锈钢基体除油、除锈、喷砂处理使表面洁净、粗化以提高黏附力;调整浸涂过程样品提升速度控制涂层厚度;涂覆样品充分干燥后在空气中1 050℃下烧结2～3 min,可获得致密光滑的陶瓷涂层。结果表明:涂层在空气中热震29次、水中热震9次,保持完整,有良好的热稳定性;涂层在空气中1 000℃下50 h连续氧化,增重约为裸样的1/20;氧化动力学曲线呈线性关系;300 h中性盐雾侵蚀无明显变化,腐蚀等级9级,外观评价为A级。

Oxide coatingsystems containing SiO2-BaO-Al2O3-Cr2O3 as the main ingredients were designed to improve the antioxidarion performance and chemical corrosion resistance of austenitic stainless steel. The technology for preparing the ceramic protective coating was studied. It was suggested that the average grain diameter (D95) of the coating powders kept as 1.52 μm and the grain diameter of 95% powders (D95) kept below 3.40 μm. Also it was suggested to keep the coating slurry viscosity tested by Ford viscosity cup as 12 ～16 s, and to degreasc, derust and sand-blast the substrate for achieving better adhesion. It was further recommended that the samples be lifted at an appropriate speed forproperly adjusting the coating thickness. And it was finally suggested that the coating samples fully dried and sintered at 1050℃ in air for 2～3 min. In addition, the corrosion resistance of the ceramic coating was primarily evaluated by conducting thermal shock test in air and water, and salt spray eroding test and high temperature oxidation test as well. Results indicate that compact and smooth ceramic coalings can be obtained by making use of the determined process. The resul-ting ceramic coating samples were able to endure 29 times thermal shock recycle in air and 9 times thermal shock in water. The weight gain of the coated sample exposed in air at 1 000 ℃ for 50 h is only 1/ 20 of that of the substrate, and the oxidation dynamic curve is domina-ted by linear correlation. Besides, the coated sample experienced al-most no change after salt spray eroding test, whose eroding degree and surface degree were determined to be 9 and A, respectively.