Precursor infiltration and pyrolysis cycle-dependent microwave absorption and mechanical properties of lightweight and antioxidant carbon fiber felts reinforced silicon oxycarbide composites.

High-performance microwave absorption materials combined with good oxidation resistance and mechanical properties are highly desirable in some extreme situations. Herein, three-dimensional (3D) needled carbon fiber felts reinforced silicon oxycarbide (SiOC/CFs) composites with excellent electromagnetic (EM) wave absorption, good oxidation resistance and mechanical properties were successfully prepared through a simple precursor infiltration and pyrolysis (PIP) process. Notably, the EM wave absorption, oxidation resistance and mechanical performances strongly depend on the PIP cycles through adjusting the content of SiOC to control the porosity and density of the composites. A substantial enhancement of EM wave absorption performance of composites is achieved via incorporation of SiOC with different PIP cycles, resulting from the matched characteristic impedance and enhanced loss ability. The minimum reflection loss (RL) of pure carbon fiber felts is -8.4 dB, whose value is decreased to -62.9 dB for the composites with 1 PIP cycle, and to -49.9 dB for the composites with 2 PIP cycles, respectively. The results indicate that the as-prepared SiOC/CFs composites with superior EM wave absorption, great oxidation resistance and mechanical properties could be considered as a great potential for the applications in harsh environments.