ABSTRACT We propose a new theoretical kinetic model of strength recovery by oxidation-induced self-healing of surface cracks in composites containing a healing agent (HA). The kinetics is a key parameter in the design of structural components that can self-heal the damage done in service. Based on three-dimensional (3D) observations of crack-gap filling, two crack-gap filling models, i.e., a bridging model and a tip-to-mouth filling model, are incorporated in the proposed kinetic model. These crack-gap filling models account for the microstructural features of the fracture surfaces, crack geometry, and oxidation kinetics of the healing-agent. Hence, the minimum and maximum remaining flaw sizes in the healed crack gaps are estimated for various healing temperatures, times, and oxygen partial pressure conditions. Further, the nonlinear elastic fracture mechanics suitable for small-sized remaining flaws, together with a statistical analysis of the original Weibull-type strength distribution, enables the prediction of upper and lower strength limits of the healed composites. Three sintered alumina matrix composites containing silicon carbide (SiC)-type HAs with various volume fractions and shapes, together with monolithic SiC ceramics, are considered. The strength of the healed-composite predicted by our model agrees well with the experimental values. This theoretical approach can be applied to HAs other than SiC and enables the design of self-healing ceramic components for various applications.

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自愈设计：自愈陶瓷强度恢复的通用动力学模型

摘要 我们提出了一种新的强度恢复理论动力学模型，该模型通过氧化诱导的含有愈合剂 (HA) 的复合材料中的表面裂纹自愈而恢复。动力学是结构部件设计中的一个关键参数，可以自我修复在使用中造成的损坏。基于裂纹间隙填充的三维（3D）观察，两个裂纹间隙填充模型，即桥接模型和尖端到嘴部填充模型，被合并到所提出的动力学模型中。这些裂纹间隙填充模型考虑了断裂表面的微观结构特征、裂纹几何形状和愈合剂的氧化动力学。因此，可以针对不同的愈合温度、时间和氧分压条件估计愈合裂纹间隙中的最小和最大剩余缺陷尺寸。更多，适用于小尺寸残余缺陷的非线性弹性断裂力学，加上对原始威布尔型强度分布的统计分析，可以预测愈合复合材料的强度上限和下限。考虑了三种含有不同体积分数和形状的碳化硅 (SiC) 型 HA 以及单片 SiC 陶瓷的烧结氧化铝基复合材料。我们的模型预测的愈合复合材料的强度与实验值非常吻合。这种理论方法可以应用于碳化硅以外的 HA，并能够为各种应用设计自修复陶瓷组件。能够预测愈合复合材料的强度上限和下限。考虑了三种含有不同体积分数和形状的碳化硅 (SiC) 型 HA 以及单片 SiC 陶瓷的烧结氧化铝基复合材料。我们的模型预测的愈合复合材料的强度与实验值非常吻合。这种理论方法可以应用于碳化硅以外的 HA，并能够为各种应用设计自修复陶瓷组件。能够预测愈合复合材料的强度上限和下限。考虑了三种含有不同体积分数和形状的碳化硅 (SiC) 型 HA 以及单片 SiC 陶瓷的烧结氧化铝基复合材料。我们的模型预测的愈合复合材料的强度与实验值非常吻合。这种理论方法可以应用于碳化硅以外的 HA，并能够为各种应用设计自修复陶瓷组件。