Effect Of Plastic Combination Phase On The Properties Of Corundum-Mullite Composites

With the widely using of the magnetic and electronic ceramics and other new functional ceramics, as main kiln materials of preparing these ceramics, corundum-mullite composites have received more attention from people. This is because corundum-mullite composites have following advantages:such as excellent high temperature strength, creep resistance, thermal shock resistance and higher using temperature (1500℃or higher), chemical stability, not easy reacting with the product loading, rich in raw materials, cost-effective and so on.The corundum-mullite composite kiln furniture which used in preparing high-grade magnetic materials and new electronic ceramics, especially, push tiles of this kind producted domesticly is in a lower lifetime (usually≤50 times), not good stability, easy to wear and fracture when used. This is mainly because the strength of the material especially the high temperature strength and the thermal shock resistance is not ideal. At the same time the firing temperature of these materials is relatively high (usually around 1700℃-1800℃), firing costs in production costs account for a large proportion and energy wasting is severe. So an important topic in the current study is how to improve the thermal shock stability and strength of corundum-mullite, while reducing the firing temperature to achieve low temperature rapid sintering ceramics, which towards improving the lifetime of corundum-mullite composites, thus reducing production costs of ceramics, saving energy and promoting the industrial producting of high-grade magnetic materials, new electronic materials and other functional ceramics has important practical significance.To improve properties of corundum-mullite materials and solve the contradiction between thermal shock resistance, strength and sintering temperature, in this paper, corundum-mullite composites were prepared using tabular alumina, sintered mullite, CT800FG and silica powder as main raw materials. Study the plastic phase such as metal Al, elemental Si and Al-Si alloy powder on sintering properties, mechanical properties, thermal shock stability, phase composition and microstructure of corundum-mullite composites, which can reacting with Al2O3 or SiO2 to generate the secondary mullite in situ after oxidation. Based on these studies, finding the best type and dosage of plastic phases, then further studying the addition of zirconium mullite on properties of materials. Results show that:(1) three kinds of plastic phases all can enhance phases all can enhance sintering properties of corundum-mullite materials, but consideration of the synthesis effect, samples which added Al-Si alloy powder have better properties than samples which added Al powder or Si powder; (2) according to results of the previous step, based on samples added the appropriate Al-Si alloy powder, replacing sintered mullite with zirconium mullite powder, can also improve properties of corundum-mullite materials.