Near net shape fabrication of porous cordierite by combination of foam gel‐casting and freeze‐drying

Abstract

It is well known that ceramic products are hard-tomachine due to their high strength and high hardness. Although the post-processing and fine processing of ceramics are technically feasible, the process is expensive and time consuming. In addition, cracks will inevitably be introduced during machining, resulting in properties reduction and ceramic products damage. 1 Therefore, it is particularly important to ensure the size and accuracy of ceramic product during preparation. Especially for porous ceramics, the shrinkage during preparation is even more difficult to avoid. [2][3][4] Therefore, the development of low-shrinkage porous ceramic preparation technology has attracted extensive attention. [5][6][7] Recently, porous cordierite ceramics with high porosity have been prepared and the sintering linear shrinkage was controlled below 2% through an in situ synthesis foam gel-casting method in our previous studies. 8,9 The near net size sintering was achieved by means of the compensation for sintering shrinkage through the volume expansion derived from phase transition and synthesis reaction. But the whole near net shape fabrication has not been achieved due to the large drying shrinkage before sintering. Large uneven drying shrinkage usually brings internal stress and microcracks, 10 which will not only cause difficulties

Experimental investigation of mass transfer and pressure drop in NH3 SCR over self-supporting Cu-ZSM-5 foam

“…The emulsion method reported by Vijayan et al was used for the preparation of the Cu-ZSM-5 foam catalyst as it is environmentally benign and capable of producing macroporous foams. 22,23 A 10 vol% slurry was prepared by dispersing 10 g Na-ZSM-5 powder in 47.5 ml water using the ammonium polyacrylate dispersant. The amount of dispersant used is 2 wt% of the Na-ZSM-5 powder.…”