Influence of mass ratios between SiC particles and chopped carbon fibers on properties of C/SiC/SiO2 porous ceramics

Abstract Transpiration cooling in the thermal protection system of hypersonic vehicles still remains a challenge due to the lack of lightweight porous ceramic with excellent permeability. C/SiC/SiO2 porous ceramics with low density and good permeability are fabricated by optimized grinding-mould pressing-sintering process. The influences of different mass ratios between SiC particles and chopped carbon fibers on the microscopic structure, mechanical performance, pore-size distribution and permeability of the porous ceramics are studied systematically. C/SiC/SiO2 porous ceramics with density of 1.092～1.327 g/cm3, compressive strength of 1.55～15.7 MPa, permeability of 5.903 × 10–8～13.434 × 10-8 mm2, as well as uniform microstructure and pore-size distribution have been obtained with the increasing of the mass ratios. Notably, the densities and compressive strengths of C/SiC/SiO2 porous ceramics improve gradually but their permeabilities decrease with the increasing of mass ratio between SiC particles and chopped carbon fibers from 0.3:1 to 1:1. The porous ceramics fabricated by optimized processing method can have a potential application in the transpiration cooling.