热障涂层对单晶高温合金多轴热机疲劳性能的影响

Influence of thermal barrier coatings on multiaxial thermo-mechanical fatigue properties of single crystal superalloy

采用电子束物理气相沉积工艺在CMSX-4单晶合金空心试管表面制备了Y_(2)O_(3)(7%~8%,质量分数)-ZrO_(2)热障涂层,然后在500~1000℃范围内对带/不带涂层试样进行了机械应变控制的热机械疲劳(TMF)和热梯度机械疲劳试验(TGMF)。结果表明,热障涂层可在一定程度上提高单晶合金试棒的疲劳寿命,同时,在相同的应变幅值下,同相位带热障涂层试样的热梯度机械疲劳寿命略高于反相位带涂层试样。试样的断口分析结果表明,同相位热机疲劳和反相位热机疲劳断口呈现显著差异,反相位疲劳试样断口具有明显的疲劳辉纹,材料蠕变和氧化对断口影响较小;同相位试样断口则明显与材料的蠕变和氧化相关。

Y_(2)O_(3)(7%-8%,mass fraction)-ZrO_(2) thermal barrier coatings were deposited on the surface of CMSX-4 single crystal alloy hollow test tube by electron beam physical vapor deposition process,then thermo-mechanical fatigue(TMF)and thermal gradient mechanical fatigue(TGMF)tests of the tube with/without coatings were investigated at 500-1000℃under mechanical strain control.The results indicate that the thermal barrier coatings can improve the fatigue life of the single crystal alloy to a certain extent,and the fatigue life of the in-plane(IP)coated specimens is slightly higher than that of the out-plane(OP)coated specimens at the same strain amplitude.Furthermore,the fracture analysis results indicate that there is significant difference in the fatigue fracture between the IP-TMF coated specimens and the OP-TMF coated specimens.Obvious fatigue striation can be observed on the fracture surface of the OP-TMF coated specimens,and creep and oxidation have little effect on the fracture,while the fracture of the IP-TMF coated specimens is obviously related to the creep and oxidation of the material.