In-situ synthesis and properties of porous cordierite ceramics with adjustable pore structure

Using high purity oxide (MgO, Al2O3 and SiO2) as raw materials, porous cordierite ceramics with a single phase and adjustable pore structure have been in-situ synthesized by foam gel-casting process. The effects of sintering temperature and foaming agent concentration on the phase composition, microstructure and properties were systematically investigated. The results indicated that pure cordierite could be obtained at sintering temperatures of 1430 degrees C and 1450 degrees C, while the sample sintered at 1450 degrees C showed better comprehensive performance. By adjusting the foaming agent concentration in the range of 2-32 g/L, the pore size of the materials could be controlled between 45.3 mu m and 151.3 mu m with the total porosity of 85.4-87.8%. When the sintering temperature was 1450 degrees C and the foaming agent concentration was 8 g/L, the prepared samples showed excellent properties and the near net size sintering was achieved. The sintering linear shrinkage was about 0.26%, the total porosity was 86.6 +/- 0.2%, the bulk density was 0.35 +/- 0.01 g/cm(3), the compressive strength was 2.63 +/- 0.33 MPa, the thermal conductivity was 0.217 +/- 0.026 W/(m.K), the thermal expansion coefficient was 1.70 x 10(-6)/degrees C, and the permeability of deionized water was 3.62 x 10(-11) m(2).