强流脉冲电子束粘结层表面改性对热障涂层热震及残余应力的影响

Effect of Surface Modification of Bonding Layers by High Current Pulsed Electron Beam on Thermal Shock Failure and Residual Stress of Thermal Barrier Coatings

中文关键词: 热障涂层 强流脉冲电子束 纳米铝膜 热震 残余应力

英文关键词: thermal barrier coatings, high current pulsed electron beam, nano Al film, thermal shock, residual stress

中文摘要:

      采用等离子喷涂技术在GH4169镍基高温合金表面制备CoCrAlY粘结层,利用电子束蒸发镀膜在CoCrAlY表面蒸镀纳米铝膜并使用强流脉冲电子束熔敷纳米铝膜进行表面改性,使用APS技术在CoCrAlY表面沉积陶瓷层制备改性热障涂层。对粘结层蒸镀铝膜表面改性涂层和普通涂层分别进行热震实验、结合强度测试和残余应力分析。实验发现,在1 050 ℃高温加热后10 ℃水淬的冷热循环条件下,改性涂层的抗热震性能优于普通涂层；热震过程中改性涂层和普通涂层热生长氧化物内产生的残余应力均为压应力,且随热震次数的增加而增大,改性涂层热生长氧化物内残余压应力增长速度小于普通涂层。拉伸结果显示,普通涂层的断裂属于混合断裂,而改性涂层断裂基本发生在陶瓷层和薄膜胶界面,未发现层间断裂。改性涂层结合强度优于普通涂层。实验结果表明,采用电子束蒸发镀膜和强流脉冲电子束技术相结合对粘结层进行熔敷铝膜的表面改性处理,可以显著提高热障涂层冷热循环服役寿命。

英文摘要:

      Thermal sprayed CoCrAlY layer was prepared by air plasma spray on the surface of Ni-based superalloy GH4169. Nano Al film was deposited on the surface of CoCrAlY by electron beam evaporation and then its surface was modified by high current pulsed electron beam. Finally, the modified thermal barrier coating was prepared by depositing ceramic layer on the CoCrAlY surface by APS. The thermal shock test, bonding strength test and residual stress analysis were conducted on the coatings after bon-ding layer surface modification by Al deposition and the ordinary coatings. The results indicated that the modified coatings present better thermal shock resistance than that of the ordinary coatings after 1 050 ℃heating and then 10 ℃ water quenching. The residual stress produced by the thermally grown oxide (TGO) of modified coatings and ordinary coatings in the process of thermal shock were both press stress, and the residual press stress increased with the increasing thermal shock cycles. In addition, the growth rate of residual press stress in TGO of modified coatings was lower than that of the ordinary coatings. The tensile test result showed that the fracture of the ordinary coating belonged to mixed fracture, while the fracture of the modified coating occurred in the interface between the ceramic layer and the film adhesive, and the interlaminar fracture was not found. The modified coatings exhibited more favorable bonding strength than ordinary coating. In conclusion, the service life of thermal barrier coatings in cold and thermal cycles can be dramatically prolonged by combined surface modification of molten Al film in the bonding layer through electric beam vacuum deposition and high current pulsed electron beam technology.