Simultaneous enhancement of mechanical and microwave absorption properties with a novel in-situ synthesis ?-Al2O3 fillers for SiCf/ SiC composites

The Al and H3BO3 mixed powder was introduced into the PCS/Xylene precursor solution as in-situ synthesis alpha-Al2O3 filler by precursor infiltration and pyrolysis (PIP) method. The in-situ synthesis filler can effectively decrease the open porosity of SiCf/SiC composites and give rise to multiple scattering of microwave and dipolar polarization. Therefore, the mechanical and microwave absorption properties of SiCf/SiC composites can be simultaneously enhanced. The effects of in-situ synthesis filler on the morphologies, flexure strength and reflection loss values of SiCf/SiC composites were investigated. With 2 wt% in-situ synthesis filler, the flexure strength of SiCf/SiC composite was 305 MPa and the maximum reflection loss (RLm) can reach - 54.68 dB with the effective absorption band (EAB) of 3.51 GHz in the X band. With 5 wt% in-situ synthesis filler, the flexure strength of SiCf/SiC composite was 207 MPa and the RLm was - 30.91 dB. Due to the inefficient infiltration process, the RLm of SiCf/SiC composites with 10 wt% in-situ synthesis filler was only - 27.36 dB. Nevertheless, the flexure strength of that composite was 259 MPa, owing to the dense matrix. Additionally, the flexure strength of SiCf/SiC composite without filler was 148 MPa and the RLm was - 26.40 dB.

Automated summary

By introducing Al and H3BO3 mixed powder as filler in the in-situ synthesis process through precursor infiltration and pyrolysis method, the mechanical and microwave absorption properties of SiCf/SiC composites can be simultaneously enhanced.