Low Thermal Expansion Cordierite

In this thesis, many factors, which effect thermal expansion coefficient of cordierite, such as compounding, material, sintering system, the way of moulding, nucleating agents, porosity and so on, were studied in detail. In order to get good quality cordierite products, low alkali materials should be used and compounding should be controlled at the side of declining to magnesia and alumina. About sintering system, most savants mainly pay attention to the firing temperature and holding time, but neglect to changing the shape of the sintering curve. Besides to study the firing temperature and holding time, a new kind of sintering curve, which can get good quality cordierite materials, was come out by contrasting different kinds sintering curves. The effect of the different quantities cordierite grog to the thermal expansion coefficient was studied aiming for the difficulty of the nucleation. Grog powders can be as genus during sinter which conduce to forming cordierite nuclei. Cordierite of thermal expansion coefficient is between 1.6×10-6/℃to 1.8×10-6/℃(Rt～800℃)was synthesized on the basis of the definitive constituent and accretion ten percent grog. The effect of the porosity on thermal expansion coefficient was also discussed, moderate porosity is beneficial to thermal expansion coefficient, but too much is bad to the capability. As a rule, the porosity is about forty percent volume. Author put forward reverse point to quick cooling can reduce thermal expansion coefficient. Because the composition is not pure quartz, but common silica glass, which thermal expansion coefficient is bigger than cordierite's, cause thermal expansion coefficient of the material rise.