La_(2)Ce_(2)O_(7)/YSZ复合热障涂层制备及高热循环寿命机理研究

Preparation of La_(2)Ce_(2)O_(7)/YSZ Composite Thermal Barrier Coating and Its Mechanism of High Thermal Cycling Lifetime

为解决目前广泛使用的氧化钇部分稳定氧化锆(YSZ)热障涂层在CMAS腐蚀条件下热循环寿命较低的问题,采用超音速等离子喷涂技术沉积了La_(2)Ce_(2)O_(7)(LC)/YSZ复合热障涂层,结合双送粉模式巧妙实现了LC与YSZ的复合,借助两种材料残余应力的相互影响,有效解决LC材料热膨胀系数在低温段的陡降问题的同时提高了复合涂层的隔热性能及抗CMAS腐蚀性能。并通过高温静态腐蚀实验及热循环实验研究了LC/YSZ复合涂层的抗CMAS腐蚀性能及其在CMAS腐蚀条件下的热循环失效行为。结果表明,LC/YSZ复合涂层的热循环寿命比传统YSZ涂层高近90%,这归因于以下3方面:(1)将LC与YSZ混合能够有效避免LC材料在低温处的热膨胀系数陡降;(2)LC/YSZ复合涂层的隔热性能优于YSZ涂层;(3)LC/YSZ复合涂层可以与CMAS反应形成由La-Ce磷灰石相、CaAl_(2)Si_(2)O8、m-ZrO_(2)和t-ZrO_(2)相组成的反应层,有效地阻止CMAS熔体渗入涂层内部。

La_(2)Ce_(2)O_(7)(LC)/yttrium partially stabilized zirconia(YSZ)composite thermal barrier coating is deposited by supersonic plasma spraying technology to solve the problem of low thermal cycling lifetime of YSZ thermal barrier coating under CMAS corrosion.The double powder feeding mode is used to realize the composite of LC and YSZ,and the problem of sudden drop of the thermal expansion coefficient of LC material at low temperature is effectively solved based on the mutual influence of the residual stress between LC and YSZ.In addition,the composite coating has better thermal insulation performance and CMAS corrosion resistance.The CMAS corrosion resistance and thermal cycling failure behavior of LC/YSZ composite coating with CMAS corrosion are studied by high temperature static corrosion test and thermal cycling test.The results show that the thermal cycle life of LC/YSZ composite coating is nearly 90% higher than that of traditional YSZ coating,which can be attributed to the following three aspects:(1)mixing LC with YSZ can effectively eliminate the sudden decrease of thermal expansion coefficient of LC material at low temperature;(2)the thermal insulation performance of LC/YSZ composite coating is better than that of YSZ coating;(3)LC/YSZ composite coating can react with CMAS to form a reaction layer composed of La-Ce apatite phase,CaAl_(2)Si_(2)O_(8),m-ZrO_(2) and t-ZrO_(2) phases,which can prevent the penetration of CMAS melt effectively.