Synthesis And Study Of Cordierite - Mullite Composites

Different ultrafine cordierite-mullite powder were prepared by sol-gel method with TEOS and A1(NO₃)₃ · 9H₂O or TEOS , Mg(NO₃)₂ · 9H₂O and A1(NO₃)₃ · 9H₂O as the main raw materials, aectic acid as activator, and ethanol as solvent . Different ultrafine cordierite powder is analyzed through DSC , XRD , SEM to determine when the ultrafine powder is formed, and the morphology of the ultrafine powder, the process of crystal growing , and the size distributions. The compositions of the powder was analyzed and the influence of sintering temperature on the crystal growing was also studied.Cordierite-mullite composite material was prepared by preheating , gringing , aging , modelling , drying and sintering . The porosity , water absorption , volume density , coefficient of thermal expansion , dielectric constant of sample were tested . The effect of temperature , material composition on sintering character and electric properties of the composite material were studied.Different ultrafine cordierite-mullite powder were prepared by sol-gel method , using TEOS, and aluminium and magnesium inorganic salts as the stating materials . The powder is of steady composition, high purity , ultrafinesize and high activity. With sol-gel method, α -cordierite and mullite wasprepared at 1200℃ which is lower than that with the original method. It wasfound that the composite material has lower coefficient of thermal expansion when relative content of cordierite is larger. Therefore, the coefficient of thermal expansion of the composite material can be changed by adjusting the relative content of cordierite and mullite in it. When the relative proportion of cordierite and mullite in the composite material is different ,the sintering temperature of the material is in a disparity. The sintering temperature is lower with small content of cordierite in the material. Higher relative content of mullite in the composite material has higher dielectric constant . Dielectric constant of the composite material can be changed by adjusting the relative proportion of cordierite and mullite in the material.