Effect of pore structure evolution on mechanical properties and thermal conductivity of porous SiC-Mullite ceramics

The porous SiC-Mullite porous ceramics with different pore size were prepared by SiC particles, kaolin, Al(OH)(3), and flake graphite, V2O5 and AlF3 were used as mineralizers, the pore size was controllable by adjusting the size of flake graphite. Then the improved empirical formula and grey theory were used to study the effect of the change in pore size on the material properties. The results showed that with the increase of mean pore size from 1.1 mu m to 8.5 mu m, the cold modulus of rupture and cold crushing strength decreased by 20.8 MPa and 13.7 MPa, respectively. And the thermal conductivity increased from 1.213 W & sdot;m(- 1)& sdot;K- 1 to 1.721 W & sdot;m(- 1)& sdot;K- 1 at 800 C. The <5 mu m pores were helped enhance the strength and decreased the thermal conductivity.