Magnetic materials on the quality of the refractory material used by the high demand, so a long time, the domestic magnetic materials production plant refractories mainly rely on imports from Japan, Germany, the price is very expensive. In this experiment, high quality raw materials were used as aggregate. Through the test of the formula and the production technology, the heat resisting and anti-erosion performance was excellent, the strength was high, the effect was good and the service life was long.
Selection of raw materials Taking into Refractory company account the use of bearing seat harsh conditions, in addition to the selection of materials with high strength, good thermal shock stability, strong resistance to erosion and other characteristics, but also on the bearing seat deflection core pollution. After repeated comparison, the final choice of mullite) corundum to be developed for the ideal seat material.
Natural mullite is rare and generally synthetic. Because mullite has good high temperature mechanics and high temperature refractory brick for sale thermal performance, the synthesized mullite and its products have high density and purity, low thermal conductivity and thermal expansion coefficient, high temperature structure strength, high temperature creep rate is low, Thermal shock resistance and strong chemical resistance, the advantages of high melting point. Corundum good elasticity, high melting point, at high temperatures with good wear resistance, chemical resistance and volumetric stability, hardness, high refractoriness. In addition, the refractory materials for furnace mullite crystal is generally columnar or prismatic, corundum crystal is generally granular, mullite, corundum according to a certain proportion with the composition of mullite) corundum composite materials, mullite, corundum with the above excellent performance , And the burning of products without pollution, so mullite) corundum bearing seat can meet the requirements of the use of magnetic materials kiln 1.
Tested the development of refractory mullite-based crystal phase, in the design of the formula to make the material to produce more mullite phase, in addition, select a reasonable particle gradation is a very critical step.
The mechanical properties of the refractory lining mullite series have been studied, and the ratio of 75B25 and 25B75 with the best mechanical properties is proposed. It is pointed out that this is due to the fact that the crystal phases are intertwined with each other The Therefore, this test uses the synthesis of mullite and fumed corundum mass ratio of 3B1 as the green aggregate for the test, the use of four-stage pellet gradation, aggregate size and gradation in the first made a lot of experimental research, For comparison, the aggregate was selected as mullite or corundum. The results showed that the thermal shock resistance of the sample was the best when the mass ratio of mullite and corundum was 3B1. After several tests, several sets of more reasonable particle gradation were obtained.
Selection of additives and their additions This test uses A-Al2O3 powder, Suzhou soil, andalusite concentrate powder, zircon powder as an additive. Their role is as follows: Al2O3 micro-powder with the bearing seat in the free SiO2 reaction to form a second mullite, thereby enhancing the product life. This is because the ferrite within the Mn, Zn, Fe and so on will be volatile at high temperatures, easy with the bearing seat in the free SiO2 reaction, resulting in bearing seat corrosion and cracking, which seriously affected the product life, so The design of the formula must be considered to reduce the free SiO2 content to the extent of the reaction with the above substances. In addition, adding A-Al2O3 powder and Suzhou soil can improve the activity of matrix material, improve the forming performance of the green body and improve the sintering reaction ability of the product.
The experimental results show that the retention rate of residual strength increases with the addition of zirconite powder after thermal shock, and decreases more than 5%. The results show that ZrSiO4 has been decomposed and reacted with alumina to form ZrO2 aggregates and mullite, and the ZrO2 aggregates are evenly distributed in the matrix, To the stone network structure. In this way, the dispersion of ZrO2 is formed on the macroscopically, and a strengthened structure of ZrO2 coalescence is formed microscopically to improve the thermal shock resistance of the material.
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