为研究以高膨胀系数的陶瓷为涂层, 低膨胀系数的陶瓷为基体的预应力陶瓷的高温力学性能, 本工作以氧化锆为涂层, 氧化铝为基体, 制得表层为拉应力的“三明治”结构ZrO₂-Al₂O₃(简称ZcAs)预应力陶瓷。同时选用基体与涂层截面比值相近的Al₂O₃-ZrO₂(简称AcZs)预应力陶瓷、纯ZrO₂和纯Al₂O₃陶瓷为参照样。结合不同温度下的弯曲强度测试结果及维氏压痕结果, 阐明预应力的存在形式及其对裂纹扩展行为的影响, 并研究预应力的温度依赖性。结果表明: ZcAs预应力陶瓷的表层受拉应力, 基体受压应力; 而AcZs预应力陶瓷的表层受压应力, 基体受拉应力。由于拉应力能够促进裂纹扩展, 而压应力能够抑制裂纹扩展, 因此室温下, ZcAs的强度比纯Al₂O₃陶瓷降低13.2%, 而AcZs的强度比纯ZrO₂陶瓷提高25.0%。此外, 无论表层是拉应力还是压应力, 都随着温度升高而降低, 这主要归因于高温导致的预应力松弛。

To study the mechanical properties at high temperature of pre-stressed ceramics which were prepared by using higher expansion coefficient materials as coating and lower expansion coefficient materials as substrate, zirconia and alumina were chosen as the coating and the substrate, respectively, to fabricate ZrO₂-Al₂O₃ (marked as ZcAs) pre-stressed ceramics with sandwich structure. Meanwhile, Al₂O₃-ZrO₂ pre-stressed ceramics (marked as AcZs, which has the similar section ratio between substrate and coating to ZcAs), ZrO₂ ceramics and Al₂O₃ ceramics were set as the reference samples. Combining the results of bending strength at different temperatures with the results of Vickers indentation, the existence form of residual stress and its influence on crack propagation behavior were clarified as well as the temperature dependence of residual stress. Results show that the residual tensile stress exists in the surface layer of ZcAs, while the compressive stress exists in the substrate. On the contrary, the compressive stress exists in the surface layer of AcZs and tensile stress exists in the substrate. Due to tensile stress promoting while compressive stress inhibiting crack growth, flexural strength of ZcAs is 13.2% lower than that of Al₂O₃, and AcZs possesses strength 25.0% higher than that of ZrO₂ at room temperature. In addition, both tensile stress and compressive stress are decreased with the increase of temperature, which is mainly attributed to the relaxation of pre-stress caused by high temperature.