7YSZ热障涂层高温氧化过程中的微结构演变和阻抗谱分析  

Microstructure Evolution and Impedance Spectroscopy Analysis of 7YSZ Thermal Barrier Coating During High-temperature Oxidation Process

作　　者：陈文龙[1,2,3] 刘敏 张吉阜 

机构地区：[1]广东工业大学材料与能源学院,广州510006 [2]广东省新材料研究所现代材料表面工程技术国家工程实验室,广州510651 [3]广东省新材料研究所广东省现代表面工程技术重点实验室,广州510651

出　　处：《中国表面工程》2016年第3期48-56,共9页China Surface Engineering

基　　金：国家重点基础研究发展计划(973计划)(2012CB625100)

摘　　要：在大气环境中,测试7YSZ热障涂层抗1 000℃高温氧化性能,以模拟发动机叶片的巡航飞行高温氧化过程。采用交流阻抗技术并结合扫描电镜及X射线衍射系统研究了高温氧化过程中TGO层生长与YSZ层微结构演变。结果表明:随着氧化时间的增加,TGO层厚度增加符合抛物线规律,在中频阶段的阻抗谱响应愈加显著。YSZ熔融颗粒在较低测试温度下表现为容抗特征,随测试温度升高逐步表现为感抗特征。阻抗谱分析显示YSZ晶粒的电阻及电容随氧化时间增加,均呈一定幅度波动变化,高温氧化对熔融颗粒本身的电学特征影响不明显;随着氧化时间的增加,YSZ晶界电阻值不断增加,电容值不断下降,表明YSZ内微裂纹发生了生长和扩展,最终导致YSZ层的剥落失效。Oxidation experiments of 7YSZ thermal barrier coatings （TBCs） were carried out at atmosphere at 1 000 -C to simulate the high-temperature oxidation process of engine blades during the cruising flight. The growth of the thermal growth oxide （TGO） layer and microstructure evolution of the YSZ layer were systematically investigated by impedance spectroscopy coupled with scanning electron microscopy （SEM） and X-ray diffraction （XRD）. Results show that the increase of the thickness of the TGO layer follows the parabolic law when increasing the time of oxidation, and the impedance response of middle frequencies is increasingly remarkable. The impedance spectroscopy of YSZ molten particles shows the characteristics of capacitance when the test temperature was relatively low, while the characteristics of inductance gradually appear with increasing test temperature. Impedance analysis shows that the resistance and capacitance of the YSZ grains fluctuant change with the increase of the oxidation time, demonstrating that the high-temperature oxidation does not apparently affect the electrical characteristics of molten particles. The resistance increases and the capacitance of the YSZ grain boundaries decreases with increasing oxidation time, suggesting the failure of the coating mainly due to the micro-cracks initiation and propagation in the YSZ layer.

关 键 词：高温氧化 阻抗谱 热障涂层 结构演变 

分 类 号：TG174.442[金属学及工艺—金属表面处理]