碳纳米线改性SiCf/SiCN复合材料的微结构调控与吸波机理

SiC fiber reinforced SiCN ceramic matrix composites with the amorphous substrate and little nano-heterogeneous interphase results in the insufficient electromagnetic wave absorption capability. The above problems limit their widely applications in broadband (8-18GHz) absorption fields. Focusing on the urgent needs of high thrust-weight ratio jet engine on SiCf/SiCN composites, the present proposal will develop a catalytic polymer infiltration and pyrolysis method (PIP). Carbon nanowires as a high quality absorbing agent will be in-situ formed by PIP method, so that muiti-scale absorbing interphase will be formed in the SiCf/SiCN compoistes to increase the polarization loss capability of matrix. The research contents include: the microstructure design and near-net fabrication mechanisms of carbon nanowires modified SiCf/SiCN composites; the influence of carbon nanowires on the electromagnetic wave absorbing properties and mechanical properties of SiCf/SiCN composites. We propose to fabricate a novel carbon nanowires modified SiCf/SiCN composites by in-situ catalytic PIP process at the temperature lower than 1000℃, and reveal the growth mechanism of carbon nanowires and the design rules of multi-scale absorbing interphase, and also clarify the electromagnetic wave absorbing mechanism of carbon nanowires modified SiCf/SiCN composites. The proposed research will enrich the electromagnetic wave absorbing theory of SiCf/SiCN compoistes.

连续SiC纤维增强SiCN陶瓷基复合材料（SiCf/SiCN）基体呈无定形态、纳米异质界面少，对电磁波损耗能力不足，这是制约其应用的瓶颈。针对航空发动机对吸波型SiCf/SiCN复合材料的迫切需求，本项目拟采用催化聚合物浸渍裂解法（PIP），在SiCf/SiCN内原位自生碳纳米线，并构筑多尺度吸波界面。研究改性SiCf/SiCN复合材料的微结构设计与制备机理，以及碳纳米线对SiCf/SiCN复合材料吸波/力学性能的影响规律。基于催化PIP法探索制备新型碳纳米线改性SiCf/SiCN复合材料，揭示碳纳米线的生长机理和多尺度吸波界面的微结构调控机制，从宽频吸波设计的角度阐明碳纳米线改性SiCf/SiCN复合材料的电磁波损耗机理。本研究的成果有助于丰富SiCf/SiCN复合材料的电磁波吸收理论体系。

针对航空发动机隐身尾喷部件对承载吸波一体化材料的迫切需求，连续SiC纤维增强SiCN陶瓷基复合材料（SiCf/SiCN）具有轻质、耐高温、抗氧化、良好的力学性能和电磁可调节性能，成为承载吸波一体化陶瓷基复合材料的关键候选材料。本项目采用催化聚合物浸渍裂解法（PIP），在SiCN陶瓷基体中原位自生碳纳米线，并构筑多尺度吸波界面。以二维SiC纤维预制体为增强体，通过化学气相渗透工艺结合催化聚合物浸渍裂解工艺制备碳纳米线增强SiCf/SiCN复合材料，研究了碳纳米线对SiCf/SiCN复合材料微结构、电磁性能、吸波和力学性能的影响规律，揭示了碳纳米线的生长机理和多尺度吸波界面的微结构调控机制，建立了复合材料的微结构演变与吸波性能和力学性能的对应关系。根据He-Hutchinson模型，通过阻抗匹配型结构设计，SiCf/SiCN复合材料在9~13.5GHz波段频率范围内RL小于-10dB，具有良好的宽频吸波性能，弯曲强度和断裂韧性分别为384MPa和12.8MPa·m1/2，SiCf/SiCN复合材料兼具良好的吸波性能和力学性能，为吸波结构型陶瓷基复合材料的设计与制备提供理论和实验基础。