Continuous silicon carbide fiber-reinforced silicon carbide ceramic matrix composites (SiCf/SiC) are promising as thermal structural materials. In this work, the microstructure and static mechanical properties of 3D-SiCf/SiC with PyC, SiC, and PyC/SiC and without an interface prepared via polymer infiltration and pyrolysis (PIP) were investigated systematically in this paper. The results show that the microstructure and static mechanical properties of SiCf/SiC with an interphase layer were superior to the composites without an interlayer, and the interface debondings are existing in the composite without an interphase, resulting in a weak interface bonding. When the interphase is introduced, the interfacial shear strength is improved, the crack can be deflected, and the fracture energy can be absorbed. Meanwhile, the shear strength of the composites with PyC and PyC/SiC interfaces was 118 MPa and 124 MPa, respectively, and showing little difference in bending properties. This indicates that the sublayer SiC of the PyC/SiC multilayer interface limits the binding state and the plastic deformation of PyC interphase, and it is helpful to improve the mechanical properties of SiCf/SiC.

中文翻译：

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不同界面的3D-SiCf/SiC复合材料的力学性能和失效行为

连续碳化硅纤维增强碳化硅陶瓷基复合材料（SiCf/SiC）作为热结构材料很有前景。在这项工作中，本文系统地研究了具有 PyC、SiC 和 PyC/SiC 且没有通过聚合物渗透和热解 (PIP) 制备的界面的 3D-SiCf/SiC 的微观结构和静态机械性能。结果表明，有界面层的 SiCf/SiC 的微观结构和静态力学性能均优于无界面层的复合材料，且无界面层的复合材料存在界面脱粘，导致界面结合较弱。引入界面相后，界面剪切强度提高，裂纹可以偏转，断裂能被吸收。同时，具有 PyC 和 PyC/SiC 界面的复合材料的剪切强度分别为 118 MPa 和 124 MPa，弯曲性能差异很小。这表明PyC/SiC多层界面的亚层SiC限制了PyC界面的结合态和塑性变形，有助于提高SiCf/SiC的力学性能。