Mechanical and microwave absorption properties of SiC_f/SiC–Al₄C₃ composite with EPD-SiO₂/ZrO₂ interphase prepared by precursor infiltration and active filler-controlled pyrolysis method

The SiO₂/ZrO₂ interphase was successfully prepared on SiC fibers by electrophoretic deposition (EPD) method and SiC_f/SiC–Al₄C₃ composites were fabricated by precursor infiltration and active filler-controlled pyrolysis process using mixed PCS and aluminum fillers as precursors. The morphology of EPD-SiO₂/ZrO₂ interphase was observed by scanning electron microscopy (SEM) and its microstructure was characterized. The results indicated that a dense and smooth SiO₂/ZrO₂ interphase can be obtained by EPD method. The effects of EPD-SiO₂/ZrO₂ interphase on the mechanical, dielectric and microwave absorption properties of SiC_f/SiC–Al₄C₃ composites were investigated. The flexural strength and fail displacement of SiC_f/SiC–Al₄C₃ composite with 330 nm thick EPD-SiO₂/ZrO₂ interphase have been dramatically improved to 360 MPa and 0.58 mm, respectively, which were four times more than those of SiC_f/SiC–Al₄C₃ composite without interphase. In addition, the complex permittivity of SiC_f/SiC–Al₄C₃ composites were improved slightly from 6.8-3.5j to 8.5-3.9j at 10 GHz with the introduction of EPD-SiO₂/ZrO₂ interphase attributed to the inhibition of reaction between aluminum fillers and SiC fibers. Moreover, the introduction of EPD-SiO₂/ZrO₂ interphase has little influence on the microwave absorption properties of SiC_f/SiC–Al₄C₃ composites and the effective microwave absorption band (RL ≤ −10dB) of SiC_f/SiC–Al₄C₃ composites with EPD-SiO₂/ZrO₂ interphase reached to 3.9 GHz in X band according to the calculation values of reflection loss (RL), indicating its promising application in the field of structural and microwave absorption.