La2Ce2O7/YSZ热障涂层抗热震性能的陶瓷层厚度影响研究

The Effect of Ceramic Layer Thickness on Thermal Shock Resistance of La2Ce2O7/YSZ Thermal Barrier Coatings

摘要:

采用实验和数值方法研究了陶瓷层厚度比对La2Ce2O7/YSZ(LC/YSZ)热障涂层热震性能的影响。实验结果表明,随着LC与YSZ厚度比的降低,涂层热震寿命显著提高,涂层失效区域逐渐向试样中心转移,剥离位置逐渐从两陶瓷层界面附近转移到LC内靠近上表面处。数值结果表明,界面边缘处较大的轴向应力与剪切应力易导致较大厚度比涂层边缘处剥落；LC表面中心区域较大的径向拉应力会导致垂直裂纹萌生,并伴随界面偏折,这是较小厚度比涂层自LC内部剥离的原因。

Abstract:

The effect of the thickness ratio between La2Ce2O7(LC) layer and YSZ layer on the thermal shock performance of La2Ce2O7/YSZ double-ceramic-layer thermal barrier coatings was studied by experimental and numerical method. The thermal cycling test indicates that with the decrease of the thickness ratio, the lifetime of double-ceramic-layer thermal barrier coatings is improved obviously and the failure region is gradually transferred to the sample center. Meanwhile the separation position is transferred from the LC/YSZ interface to the inner LC near the upper surface. The numerical results show that the lager axial tensile stress and shear stress of the interface of LC layer and YSZ layer at the edge leads to the spallation failure at the coating edge. The larger radial tensile stress at the central area of the LC surface leads to the initiation of vertical cracks accompanied by the interface deflection, which is the reason why the coating is peeled off from the inside of the LC layer.