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Investigation on Factors Affecting Properties of Micropored Lightweight Mullite Aggregate

Author: ShanGuoQiang
Tutor: ZhouNingSheng
School: Henan University of Science and Technology
Course: Materials Science
Keywords: Mullite Microporous Lightweight aggregate Performance Calcining system Additives Insulation materials Refractories
CLC: TF065.1
Type: Master's thesis
Year: 2010
Downloads: 101
Quote: 2
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Abstract

The thermal insulation of the various types of industrial furnaces and thermal equipment is an important aspect of energy saving. The use of lightweight refractory material is an effective method for realizing energy saving. Development and application of high-performance light of monolithic refractories for achieving significant energy savings. Developed with excellent insulation properties of refractory aggregate on the development of high-performance lightweight castable an important role. The work of industrial alumina powder and silica powder as a starting material, anthracite burning Lost and Found, wet co-grinding, natural subsidence drying into blank, and then calcined to prepare micron aperture light mullite aggregate. Study the mullite synthesis microporous material performance factors, including calcined system, additives and industrial alumina phase. First industrial alumina, silica powder and anthracite mixture blank by means of DSC-TG thermal analysis Thermal Behavior of. Anthracite about 600 ℃ Loss on ignition mixture in the beginning of 1200 ℃ mullitization. Compare the the two calcining systems mullite conversion rate: a monotonic warming and insulation; another insulation in both high and low temperature segment. By XRD analysis of the phase composition of the synthetic material. The study found that the temperature is the impact elements mullitization, mullite formation is affected by temperature is much larger than the holding time. Using the first high-temperature short-time thermal insulation, and then calcined at a slightly lower temperature insulation system is conducive to mullitization and reduce energy consumption. Added to the role of the seed crystal from the pre-synthetic sintered mullite stone 1%, 3%, 5% and 7%, synthetic material bulk density, compressive strength at room temperature increased, but the the mullite conversion rate increase was not obvious, are about 60%; were introduced 1%, 3%, 5% and 7% of yttrium oxide, a bulk density of synthetic material, the compressive strength has a tendency to increase; adding 1%, 3%, 5% and 7% aluminum fluoride, synthetic material bulk density, compressive strength at room temperature showed a downward trend. The industrial alumina phase composition as the starting material has great influence on the performance of the synthetic material to gamma-Al ₂ O ₃ main crystalline phase industrial alumina high reactivity, more help mullitization, low bulk density, high porosity porous lightweight mullite. By means of mercury porosimetry pore size distribution of the synthetic material made detection found synthetic materials aperture scale mainly concentrated in the range of 3 to 5μm, uniform distribution of pores. Synthetic material microstructure by means of SEM observation and analysis. The development of microporous light mullite the stone aggregate Al ₂ O ₃ content of 70%, mullite conversion rate of not less than 50% porosity more than 50%, the bulk density of less than 1.2g/cm3. The study showed that the synthesis of such lightweight porous mullite, a suitable calcining temperature of 1350 ° C to 1450 ° C. Due to the limited contact between the surface of the material in the kind of lightweight materials, the solid phase mass transfer difficulties, mullite conversion rate, sintering modest changes with temperature and holding time. This work was prepared in light porous mullite stone below 1500 ℃, material, stable performance, no temperature rise of the material large sintering shrinkage and lightweight porous mullite stone mullite The conversion rate was controlled at 50% to 65%, there are still remnants of the system corundum and silicon dioxide, making the synthetic material in the process of further heating, you can continue to occur mullitization to offset high temperature sintering shrinkage.

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