钼电极表面Y2O3-玻璃基涂层抗氧化性能研究

目的提高钼电极在玻璃炉窑烘窑过程中的抗氧化性能。方法在纯钼基体表面制备不同Y2O3含量的玻璃基抗氧化涂层。对涂层分别在800、1000、1200℃下进行抗氧化测试,利用扫描电镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)对涂层在氧化前后的形貌、成分和物相进行检测,利用热分析仪对涂层粉体进行差热分析(DTA)。结果随着Y2O3成分含量的增加,硅酸盐玻璃的软化点温度不断降低,晶化放热峰也越来越低。Y2O3含量为10%和20%的涂层表面结构完整,整体比较致密,在1200℃高温氧化条件下,在第1h内出现增重,之后随着加热时间的延长,增重趋于稳定。Y2O3含量为30%的涂层表面呈致密片状结构,部分出现脱落,样品在氧化过程中出现明显失重。结论Y2O3含量为10%的Y2O3-玻璃基涂层经过1200℃抗氧化实验后,表面完整,试样增重较少,性能优良。涂层截面分为过渡层、中间层和最外层。过渡层主要为MoO2和MoO3,中间层主要是BaMoO4,最外层主要是SiO2。涂层抗氧化机理为互熔反应型保护机理和惰性熔膜屏蔽型保护机理。

Oxidation Resistance of Y2O3-glass Coating on Molybdenum Electrode Surface

The work aims to improve the oxidation resistance of the molybdenum electrode in the process of heating in the empty kiln.Oxidation-resistant glass coatings with different Y2O3 contents were prepared on the surface of the molybdenum substrate.The oxidation resistance of the coatings was tested at 800℃,1000℃and 1200℃.The microstructure,composition and phase of the as-prepared specimens were tested by scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS)and X-ray diffraction(XRD).In addition,the differential thermal analysis(DTA)was carried out to the coating powder by thermal analyzer.The softening temperature of silicate glass continuously decreased,and the peak of crystallization exothermic got lower and lower with the increase of the Y2O3 content.The coating surface with 10%and 20%Y2O3 was complete and dense.The weight increased in the first hour under the oxidation condition of 1200℃,and then tended to be stable with the heating time.The coating surface with 30%Y2O3 showed a dense structure but partially spelled which resulted in the significant weight loss during oxidation.After oxidized at 1200℃,the Y2O3-glass coating with 10%Y2O3 shows excellent oxidation resistance performance,with intact surface and less increased weight.The cross-section of the coating is composed of transition layer,intermediate layer and outermost layer.The phase composition of the transition layer,the middle layer and the outermost layer is mainly MoO2/MoO3,BaMoO4 and SiO2,respectively.The oxidation resistance mechanism of the coating is a mutual melting reaction type protection mechanism and an inert melt film shielding type protection mechanism.