The Influence of SiO(2) + SiC + Al (H(2)PO(4))(3) Coating on Mechanical and Dielectric Properties for SiC(f)/MWCNTS/AlPO(4) Composites

SiC fiber-reinforced AlPO(4) matrix (SiC(f)/MWCNTs/AlPO(4)) composites were fabricated using a hot laminating process with multi-walled carbon nanotubes (MWCNTs) as the absorber. A coating prepared from SiO(2) + SiC + Al (H(2)PO(4))(3) was applied to the surface of the SiC(f)/MWCNTs/AlPO(4) composites prior to an anti-oxidation test at 1273 K in air for 40 h. The anti-oxidation effect was verified by a three-point bending test, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and a dielectric property test. Anti-oxidation mechanism investigations revealed that the coating effectiveness could be attributed to three substances, i.e., SiO(2), SiP(2)O(7,) and SiO(2) + AlPO(4) solid solution from the reactions of SiC + O(2)→SiO(2) + CO, SiO(2) + P(2)O(5)→SiP(2)O(7) and SiO(2) + AlPO(4)→solid solution, respectively.