Study On Porous Cordierite Ceramic Prepared By Gel-Casting Method

Cordierite (Mg2Al4Si5O18) ceramics has won widely application in insulation materials, high-temperature filter material and the catalyst support material due to low coefficient of thermal expansion (CTE), high temperature stability and good mechanical properties. The CTE of cordierite made in foreign is lower than that made in domestic. This paper mainly studies using talcum powder, kaolin and alumina as raw materials to prepare porous cordierite ceramic catalyst carrier material. Porous cordierite ceramic catalyst carrier material, which has low thermal expansion coefficient, good mechanical properties, was prepared by optimizing the preparation process.This paper mainly analyzed and explored the following aspects:explored the influence of Alumina particle size and preparation method on the properties of porous cordierite ceramic catalyst carrier material; effects of ratio of the raw materials, agglomeration process, solid content in the gel-casting process and cerium oxide (CeO2) content on the properties of porous cordierite ceramic.When 1.5μmα-Al2O3 was employed as the raw material, the CTE of porous cordierite ceramic is low, and the value of average CTE is 1.65×10-6℃-1.The comprehensive properties of porous cordierite ceramic, which is prepared by gel-casting, is higher than that prepared by molding method. The micropores are circular and distribute uniformly in the porous cordierite ceramic made by gel-casting. And the average porosity is up to 68.1%, the average CTE is up to1.53×10-6℃-1, the average compressive strength is 13.44 MPa.When monomer content is 7.5wt%, pH=8 and solid content is 30.53vol%, the slurry curing time is moderate. It can guarantee that the slurry has good filling formability and the slurry can be evenly dispersed. Suitable solid content can improve the comprehensive properties of porous cordierite ceramic. When the solid content is 30.53vol%,the properties is the best, porosity is 55.43%,the compressive strength is 25.87MPa and the CTE is 1.66×10-6℃-1. When the component ratio is biased to MgO and Al2O3 (i.e.14.0%MgO、37.6%Al2O3、48.4%SiO2), the CTE of porous cordierite ceramic is lower and the average CTE is 1.69x 10-6℃-1.When the sintering temperature is 135O℃,3h insulation can get the optimal properties of the porous cordierite ceramic. In the samples cordierite phase content is high, pores are uniformly distributed, the CTE is as low as 1.691.69×10-6℃-1, porosity is 58.53% and compressive is 22.44MPa.The addition of CeO2 can promote the formation of cordierite phase and the densification of the porous cordierite ceramic. With the increase of the content of CeO2, the porosity of the samples decreased, the compressive strength increased and the CTE decreased and then increased. When the content of CeO2 is 0.2wt%, the phase of the sample is cordierite phase, and the CTE is low. The CTEs of sintered samples at 1250℃ and 1350℃ are 1.92×10-6℃-1 and 1.52×10-6℃-1,the compressive strength are 8.61MPa and 25.09MPa, respectively, and the porosities are 60.1% and 57.2%.