Here we show that when the temperature exceeded 1200 °C, the tensile strength drops sharply with change of fracture mode from fiber pull-out to fiber-break. Theoretical analysis indicates that the reduction of tensile strength and change of fracture mode is due to the variation of residual radial stress on the fiber–matrix interface coating. When the temperature exceeds the preparation temperature of the composites, the residual radial stress on the fiber–matrix interface coating changes from tensile to compressive, leading to the increase of the interface strength with increasing temperature. The fracture behavior of SiC–SiC composites changes from ductile to brittle when the strength of fiber–matrix interface coating exceeds the critical value. Theoretical analysis predicts that the high temperature tensile strength can increase with a decrease in fiber–matrix interface thickness, which is verified by experiments.

中文翻译：

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家用Hi-Nicalon型SiC纤维界面涂层对SiC-SiC复合材料高温力学性能的影响

此处我们表明，当温度超过1200°C时，拉伸强度会随着断裂模式从纤维拉出到断裂而急剧下降。理论分析表明，抗拉强度的降低和断裂模式的改变是由于纤维-基体界面涂层上残余径向应力的变化所致。当温度超过复合材料的制备温度时，纤维-基体界面涂层上的残余径向应力会从拉伸变为压缩，从而导致界面强度随温度的升高而增加。当纤维-基体界面涂层的强度超过临界值时，SiC-SiC复合材料的断裂行为从韧性转变为脆性。