Effects of SiC particle size on flexural strength, permeability, electrical resistivity, and thermal conductivity of macroporous SiC

Abstract

In this study, macroporous SiC ceramics were fabricated via in situ liquid-phase bonding using an Al2O3-Y2O3-SiO2 bonding additive at 1500 degrees C. The pore size of the ceramics was successfully varied from 7.8 to 45.5 mu m by increasing the SiC particle size from 37.6 to 262.6 mu m, without changing the porosity. The effects of the SiC particle size and pore size on the flexural strength, permeability, and electrical resistivity of the ceramics were investigated. The pore size and SiC particle size significantly affected the properties of the macroporous SiC. With an increase in the pore size and SiC particle size, the flexural strength and electrical resistivity of the ceramics decreased significantly, while the permeability and the thermal conductivity increased considerably. The porous SiC with a pore size of 45.5 mu m and a porosity of 37.8% exhibited a high permeability of 21.2 x 10(-12) m(2), relatively high flexural strength of 20.6 MPa, moderate electrical resistivity of 3.8 x 10(5) Omega cm, and high thermal conductivity of 66.4 Wm(-1)K(-1).