Effects of CeO2 addition on the properties of cordierite-bonded porous SiC ceramics

Cordierite-bonded porous SiC ceramics were fabricated with and without CeO2 addition in air by an in situ reaction bonding technique. The effects of CeO2 addition on the phase composition, microstructure and properties of porous SiC ceramics were investigated. It was found that the CeO2 addition strongly promotes the phase transformation towards cordierite while inhibits the formation of spinel. With CeO2 addition, the neck growth was enhanced, and the mechanical properties of porous SiC ceramics were improved. When 2.0 wt.% CeO2 was added, a flexural strength of 35.3 MPa was achieved at an open porosity of 42.1%. Pore size distribution characterization by mercury porosimetry indicated that 2.0 wt.% CeO2 addition enlarged the average pore size of porous SiC ceramics and introduced a bigger homogeneity in pore size. In addition, it was found that higher permeability was obtained after adding 2.0 wt.% CeO2. Moreover, the thermal shock resistance of cordierite-bonded porous SiC ceramics was also improved by the addition of CeO2.