Ceramic matrix composites (CMCs) can be microwave‐absorbent when endowing the composite constituents with proper dielectric properties. In this work, we report a new method to enhance the microwave‐absorbing property of CMCs by in situ fabrication of a carbon‐rich interphase at the fiber/matrix interface. This was achieved in a SiC fiber reinforced SiC matrix (SiCf/SiC) composite fabricated by precursor infiltration and pyrolysis (PIP). We found that as the PIP temperature increased from 800 to 1000°C, the microwave‐absorbing property of the SiCf/SiC composite was significantly enhanced at X band, which also surpassed those of the SiC fiber and monolithic SiC ceramic fabricated at the same temperature. The dominant mechanism was studied by decoupling the effect of individual SiC fibers, SiC matrix, and fiber/matrix interface. The results showed that the SiC fiber and SiC matrix were barely microwave‐absorbent, due to their low dielectric losses. The microwave‐absorbing mechanism was finally ascribed to the fiber/matrix interface, which was carbon‐rich, containing Si and O elements. The interphase showed a conductivity that was superior to that of the fiber and the matrix, and mainly dominated the dielectric property of the overall composite. The results highlight the role of carbon‐rich interphase on the microwave‐absorbing property of CMCs.

中文翻译：

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X波段前体渗透和热解衍生的SiCf / SiC复合材料的增强的微波吸收性能：富碳相间的作用

当赋予复合材料适当的介电性能时，陶瓷基复合材料（CMC）可以吸收微波。在这项工作中，我们报告了一种通过在纤维/基质界面处原位制造富碳中间相来增强CMC的微波吸收性能的新方法。这是通过前驱体渗透和热解（PIP）制成的SiC纤维增强SiC基质（SiCf / SiC）复合材料实现的。我们发现，随着PIP温度从800°C升高到1000°C，SiCf / SiC复合材料在X波段的吸波性能显着增强，也超过了在相同温度下制造的SiC纤维和整体式SiC陶瓷的吸波性能。 。通过将单个SiC纤维，SiC基质和纤维/基质界面的作用解耦，研究了主导机理。结果表明，由于SiC纤维和SiC基体的介电损耗低，它们几乎不吸收微波。最终，微波吸收机制归因于纤维/基体界面，该界面富含碳，包含Si和O元素。该中间相显示出的导电性优于纤维和基体的导电性，并且主要支配了整个复合材料的介电性能。结果强调了富碳相间对CMCs微波吸收特性的作用。并且主要支配着整个复合材料的介电性能。结果强调了富碳相间对CMCs微波吸收特性的作用。并且主要支配着整个复合材料的介电性能。结果强调了富碳相间对CMCs微波吸收特性的作用。