基于热解碳/氮化硼镶嵌纳米界面构筑宽温域结构型吸波CMC研究

升温中电导损耗的急剧增大导致现有CMC介电性质的强温度依赖性，不能满足新一代航空发动机高温构件的宽温域隐身需求。为解决该问题，项目基于温度变化中电导损耗和界面极化损耗“反向变化”的客观规律，提出构造一种由电导损耗和界面极化损耗组成的损耗型PyC/BN纳米镶嵌界面，通过界面结构优化促进升、降温中两种损耗的“此消彼长”，进而降低CMC介电温度敏感度、发展宽温域吸波CMC的新思路。拟系统研究镶嵌界面的制备工艺、界面结构（PyC结构、刻蚀结构、BN结构、SiC纤维基底编织结构等）对镶嵌界面电导损耗、界面极化损耗、介电常数及其温度依赖性的影响，揭示PyC刻蚀结构的控制机制、强界面极化的形成机制等关键科学问题，发展介电可调、低温度依赖界面的制备方法。进而，结合介观多层吸波结构的设计应用，制备出吸波CMC，系统研究温度作用下其微观结构与性能的演变规律，揭示相关机制，发展宽温域承载-吸波的协同与优化方法。

Traditional CMC show a strong temperature dependency of dielectric properties due to their continuously increasing conductive loss during heating process, which inhibits their wide temperature range application as radar stealth components of aero-engines. To address this problem, based on the inverse relationship of conductive loss and interfacial polarization loss versus temperature, we present a novel method to fabricate dielectric loss interface with a low temperature dependence and then develop electromagnetic absorbing CMC suitable for wide temperature range. Concretely, such an interface possesses PyC/BN mosaic nanostructures constructed by a combined process of controllable corrosion and chemical vapor infiltration. Due to the nonpolar structures of PyC and BN, this mosaic nano-interface is pure dielectric system only with conductive loss and interfacial polarization loss. By optimizing the nano-interface structure, the proportion of the two kinds of loss routes is expected to be adjusted, which would help to realize the tradeoff between conductive loss and interfacial polarization loss during the temperature variation and then stabilize the dielectric properties of the nano-interface. The preparation processes of PyC/BN mosaic nano-interface, the effects of PyC structure, corrosion structure, BN structure, and SiC fiber braided structure on the conductive loss, interfacial polarization loss, permittivity, and their temperature dependencies will be studied systematically. Based on the above work, the control mechanism of PyC corrosion structure (especially the edge structure) and the forming mechanism of strong interfacial polarization will be in-depth explored. And the design and fabrication method of dielectric PyC/BN nano-interface with adjustable permittivity and low temperature dependency will be developed. Further, combining the use of multilayered absorbing structure, this project will prepare wave-absorbing CMC, investigate the evolution rule of microstructures and structural and dielectric properties under the influence of temperature, and then explore the related relationships. Based on this, the fabrication method of CMC with good mechanical properties and wave-absorbing abilities for wide temperature range will be developed.