Near net size sintering of porous cordierite ceramics with excellent properties

Abstract

During the sintering process of porous ceramics, large volume shrinkage is often accompanied, which affects their preparation, porosity and properties vastly. Therefore, controlling and reducing the shrinkage in the preparing process is one of key points for high performance porous ceramics. Herein, the near net size sintering of high purity porous cordierite ceramics was achieved by means of the compensation for sintering shrinkage through the volume expansion derived from phase transition and synthesis reaction using Al2O3, SiO2 and MgO as starting materials. Through adjusting the solid content in the initial slurry of foam-gelcasting method from 20 to 30 vol%, the sintering linear shrinkage could be controlled in the range of −1.4–1.43%. Large porous cordierite ceramic parts with both relatively complex shape and high porosity (>85%) could be easily fabricated only using this method. The results also showed that when solid content was selected as 25 vol%, the linear shrinkage was low to −0.7% and the samples possessed both high porosity as 85.8% and high compressive strength as 2.6 MPa. The permeability coefficient was 2.07 × 10−11 m2 and the thermal expansion coefficient was 1.6 × 10−6/oC. This study might open an avenue for production and broaden the wide application of porous cordierite ceramics with high porosity.