The Sintered AZS brick is made of zircon and alumina as the main raw materials, and the pre-synthetic material is used as the aggregate. Because the blank is infertile, the effect of increasing the density of refractory bricks by relying only on increasing the forming pressure is not good. The increase in the number of times of pressing of large products will also lead to the phenomenon of spalling and uneven density. It is necessary to adjust the critical particle size composition, add a composite binder and a small amount TI02, MgO sintering aid and enhanced sintering measures to achieve the purpose of dense sintering.
This reaction is an irreversible reaction and is also called an "in situ reaction". Due to the large volume effect produced in the reaction sintering process, which causes the body to deform and crack, only zircon mullite aggregates can be pre-synthesized, and sintered or fused corundum raw materials can be used to produce mullite, clinite and corundum Materials are superior to two-phase materials in terms of strength and thermal shock resistance. The microstructure of sintered AZS bricks is characterized by finely distributed fine zirconia particles between the main crystalline phases mullite and corundum.
Electrofusion recombination AZS bricks are made by melting AZS clinker, scraps or recycled residual bricks as raw materials, and adding a small amount of kaolin or alumina as a binder. When heated to a high temperature, the fused AZS aggregate exudates the glass phase and the binder forms mullite, which promotes the product to sinter. The peritectic reaction of the glass and crystal phases in the fused AZS aggregate will also form mullite. At this time, mullite and Zr02 are in the form of encapsulation and encapsulation, which is helpful for the sintering of AZS particles of different sizes. Using the "white sinterability" of fused AZS aggregates is the basic principle of producing and combining AZS bricks.
The high-temperature firing electrofusion and AZS bricks have the following microstructural changes:
1. The coarse-grained glass phase exudates to the surface of the particles and reacts with A1203, forming a mullite shell to seal the exudation channel so that the peritectic reaction proceeds inside the particles;
2. The molten AZS powder glass meets the active A1203 reaction, and the matrix is mullite. The microstructure of the combined AZS brick has the structural characteristics of dense combination of mullite and corundum zirconia eutectic.
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