Determination Method of Thermal Expansion Coefficient of Cordierite

Cordierite ceramics were prepared by using talc,bauxite and kaolin clay as starting materials.According to the detected result of XRD step-scanning from 25° to 35°by a high temperature X-ray diffractometer,2θ and d values of five peaks of cordierite crystal were ascertained.Then the least squares technique was used to calculate the crystal parameters:at 25℃,a=b=0.981 8nm,c=0.927 4 nm,V=0.774 3 nm3;at 600℃,a=b=0.982 0 nm,c=0.926 2 nm,V=0.773 5 nm3.The crystal volumetric coefficient of thermal expansion(CTE)and linear CTE along a and c axes were calculated,αV=2.33×10-6℃-1,αa=αb=3.27×10-6℃-1,αc=-4.19×10-6℃-1.The average CTE of cordierite crystal is as low as 0.78×10-6℃-1.