Improvement dielectric and microwave properties of SiC_f/SiC-AlPO₄composites prepared by precursor infiltration and pyrolysis process

SiC_f/SiC-AlPO₄composites were prepared with dual matrix precursor of polycarbosilane and aluminum dihydrogen phosphate during the PIP process to optimize the dielectric and microwave absorption properties at 8.2–12.4 GHz. Both complex permittivity and tanδ of the composites with simplex SiC and dual SiC-AlPO₄matrix show obvious sensitive behavior with the test frequency. The SiC_f/SiC composites exhibit poor reflection loss values owing to the deviation of impedance matching caused by the high complex permittivity. With introduction of AlPO₄into SiC_f/SiC composites, the complex permittivity decreased to proper levels and the microwave absorption properties are significantly improved over the whole test frequency ranges. The results indicates that the minimum RL values and bandwidth below −10 dB for the SiC_f/SiC-AlPO₄composites reach-22.8 dB and 4.2 GHz, respectively.