高温熔烧法在304不锈钢表面制备硅酸盐基陶瓷涂层的性能

Properties of silicate-based ceramic coating prepared on the surface of 304 stainless steel by high-temperature melting method

以"硅酸钠+硅酸钾"溶液(质量比1:2)为粘结剂,采用高温(800°C)熔烧法在304不锈钢表面制备了4种陶瓷骨料含量不同的硅酸盐陶瓷涂层。使用扫描电镜、X射线衍射仪和热重分析仪表征了所得涂层的形貌、物相和成膜过程中的质量变化,考察了涂层的高温氧化动力学行为,探讨了涂层厚度与结合强度之间的关系,测试了涂层的抗热震性能。结果表明,以8%Al粉、6%SiC、6%B_4C、4%钛白粉和4%玻璃粉制备的涂层表面平整。基体中的Fe元素与陶瓷骨料组分之间相互扩散与渗透,形成了AlB_2、Fe_xTi_yO_z等新的晶相。该涂层在厚度为150μm时与基体的结合强度为26.1 MPa,经1 100℃高温氧化5 h后单位面积氧化增重量仅为0.21 mg/cm^2,表现出优异的抗高温氧化性能。该涂层的热膨胀系数与金属基体最接近,因而表现出最好的抗热震性能。

Four silicate-based ceramic coatings with different contents of ceramic aggregates were prepared on the surface of 304 stainless steel using a sodium silicate plus potassium silicate （mass ratio of 1：2） solution as binder by melting at a high temperature （800℃）. The morphology, phase composition and mass variation during the film-forming processes of the coatings were characterized by scanning electron microscope, X-ray diffractometer and thermogravimetric analyzer. The high-temperature oxidation kinetic behaviors of the coatings were studied. The relationship between thickness and bonding strength of coating was discussed. The thermal shock resistance of coatings were tested. The results showed that the coating prepared with AI powder 8%, SiC 6%, BaC 6%, titania 4% and glass powder 4% has a flat surface. There is a mutual diffusion and penetration between Fe element in metal matrix and ceramic aggregates, leading to the formation of new crystal phases including AlB2 and FexTiyO2. The coating with a thickness of 150μm features a bonding strength of 26.1 MPa with the steel substrate and a weight gain of only 0.21 mg per cm2 after being oxidized at 1 100℃ for 5 h, showing an excellent high- temperature oxidation resistance. The coating shows the best thermal shock resistance because its thermal expansion coefficient is the most similar to that of the steel substrate.