Mechanical and dielectric properties of SiCf/SiC composites fabricated by PIP combined with CIP process

2D KD-1 SiC fiber fabrics were employed to fabricate SiCf/SiC composites by an improved polymer infiltration and pyrolysis (PIP) process, combined with cold isostatic pressing (CIP). The effect of CIP process on the microstructure, mechanical and dielectric properties of SiCf/SiC composites was investigated. The infiltration efficiency was remarkably improved with the introduction of CIP process. Compared to vacuum infiltration, the CIP process can effectively increase the infiltrated precursor content and decrease the porosity resulting in a dense matrix. Thus SiCf/SiC composites with high density of 2.11 g cm−3 and low porosity of 11.3% were obtained at 100 MPa CIP pressure, together with an increase of the flexural strength of the composites from 89 MPa to 213 MPa. Real part (ε′) and the imaginary part (ε″) of complex permittivity of SiCf/SiC composites increase and vary from 11.7-i9.7 to 15.0-i12.8 when the CIP pressure reaches 100 MPa.