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The difference between sintered AZS brick and electrofusion combined with AZS brick
2019-10-16 10:18:04Sintered AZS bricks are made of zircon and alumina as the main raw materials, and pre-synthesized materials are used as aggregates. Since the billet is an inert material, it is not effective to increase the molding pressure to increase the density of the product. The increase in the number of presses of large products may also lead to uneven cracking and density. It is necessary to adjust the critical particle size composition, add the composite binder and a small amount of TiO2. , MgO combustion aid and strengthening sintering to achieve the purpose of dense sintering.
The production principle is based on the solid phase reaction between ZrSiO4-AI2O3:
3AI2O3+ 2ZrSiO4-3AI2O3-2SiO2+ 2ZrO2
This reaction is an irreversible reaction and is also referred to as "in situ reaction". Due to the large volume effect in the reaction sintering process, resulting in deformation and cracking of the green body, only the pre-synthesized zirconium mullite aggregate, combined with sintered or fused corundum raw materials, can produce mullite, oblique zircon and corundum three-phase. Materials are superior to two-phase materials in terms of strength and thermal shock resistance. The microstructure of the sintered AZS brick is characterized by the uniform distribution of fine oblique zircon particles between the main crystalline phase mullite and corundum.
The electrofusion and AZS bricks are made by casting AZS clinker, scrap or recycled brick (clearing the adhered glass), adding a small amount of kaolin or alumina as a binder. When heated to a high temperature, the fused AZS aggregate exuded the glass phase and the binder to form mullite, which promotes sintering of the article. The peritectic reaction of the glass phase and the crystalline phase in the fused AZS aggregate also forms the mullite petrochemical. At this time, the mullite and ZrO2 are wrapped and wrapped in the form of the wife, which contributes to the sintering of the AZS particles of different grain-level melting and casting. The use of melt-cast AZS aggregates as "self-sintering" is the basic principle of producing and combining AZS bricks.
The microstructure changes of high temperature firing and electrofusion combined with AZS bricks are mainly:
1 The coarse-grained glass phase exudes to the surface of the particle and reacts with AI2O3 to form a mullite shell to close the exudation channel so that the peritectic reaction proceeds inside the particle;
2 The molten AZS powder glass phase reacts with the active AI2O3, and the matrix is mullite. Combined with the AZS brick microstructure, it has the structural characteristics of dense combination of mullite and corundum oblique zircon co-crystal.
