Excellent electromagnetic wave (EMW) absorbing materials with high-temperature stable and superior mechanical properties are among the most promising candidates for practical application. Here, novel hydrothermal carbon coated three-dimensional (3D) needled carbon fiber reinforced silicon-boron carbonitride (HC-CF/SiBCN) composites with a hierarchical A (CF)/B (HC)/C (SiBCN) structure were constructed and prepared for the first time by combining hydrothermal transformation and precursor infiltration and pyrolysis (PIP) process. The thickness of the HC coating controlled by the glucose concentration played a crucial role in tailoring the EMW capacity of the composite. The incorporation of SiBCN could not only effectively improve the oxidation resistance but also actively enhance the mechanical properties of the HC coated CF structure. Compared to the weak high-temperature oxidation resistance and mechanical properties of pristine 3D needled CF felt, the composites after the introduction of HC and SiBCN were thermostable in air atmosphere beyond 1000 °C to about above 70% weight retention, and the maximum flexural and compression strength of the composites could reach to 23.51 ± 1.37 and 12.22 ± 1.12 MPa, respectively. A substantial enhancement of EMW absorption ability was achieved through incorporation of HC and SiBCN, which could be attributed to the matched characteristic impedance and enhanced loss ability, whose optimization EMW absorption performance was the minimum reflection loss (RL_min) of −52.08 dB and effective absorption bandwidth (EAB) of 7.64 GHz for the composite obtained by two PIP cycles with 24 wt% glucose solution, demonstrating that the HC-CF/SiBCN composites with high-temperature stable, excellent mechanical and superior EMW absorption properties could be considered as a promising candidate for the applications in harsh environments.

具有高温稳定性和优异机械性能的优异的电磁波（EMW）吸收材料是实际应用中最有希望的候选材料之一。在这里，构建并制备了具有分层A（CF）/ B（HC）/ C（SiBCN）结构的新型热液碳包覆的三维（3D）针状碳纤维增强硅硼碳氮化物（HC-CF / SiBCN）复合材料首次将水热转化与前体浸润和热解（PIP）过程相结合。由葡萄糖浓度控制的HC涂层厚度在调整复合材料的EMW能力方面起着至关重要的作用。掺入SiBCN不仅可以有效地提高抗氧化性，而且还可以积极增强HC涂层CF结构的机械性能。与原始3D针刺CF毡的高温抗氧化性和机械性能相比，引入HC和SiBCN后的复合材料在超过1000°C的空气中可稳定达到70％以上的重量保持率，并且最大挠曲性和复合材料的抗压强度分别可以达到23.51±1.37 MPa和12.22±1.12 MPa。通过掺入HC和SiBCN可以大大提高EMW的吸收能力，这可以归因于匹配的特性阻抗和增强的损耗能力，其优化的EMW吸收性能是最小的反射损耗（RL 引入HC和SiBCN后的复合材料在超过1000°C的空气气氛中是热稳定的，约70％以上的重量保持率，复合材料的最大挠曲和压缩强度分别达到23.51±1.37和12.22±1.12 MPa。通过掺入HC和SiBCN可以大大提高EMW的吸收能力，这可以归因于匹配的特性阻抗和增强的损耗能力，其优化的EMW吸收性能是最小的反射损耗（RL 引入HC和SiBCN后的复合材料在超过1000°C的空气中可稳定达到约70％的重量保持率，复合材料的最大挠曲和压缩强度分别达到23.51±1.37和12.22±1.12 MPa。通过掺入HC和SiBCN可以大大提高EMW的吸收能力，这可以归因于匹配的特性阻抗和增强的损耗能力，其优化的EMW吸收性能是最小的反射损耗（RL_min）为-52.08 dB，通过24％葡萄糖溶液的两个PIP循环获得的复合材料的有效吸收带宽（EAB）为7.64 GHz，表明HC-CF / SiBCN复合材料具有高温稳定性，优异的机械性能和优越的EMW吸收特性可以被认为是在恶劣环境中应用的有希望的候选者。