Classification, Preparation And Properties Of Sintered Zirconia Corundum Bricks For Glass Furnaces

Corundum brick is a kind of refractory bricks collectively, corundum bricks are actually divided into many grades, a variety of different corundum materials. In general, the aluminum content is greater than 85% of the refractory brick is called corundum brick, corundum can be divided into brown corundum, white corundum, plate corundum. So there are many kinds of corundum bricks, there are according to the aluminum content of high and low points, there are different bulk density points; there are composite forms of refractory bricks, there are different production methods of corundum bricks; there are also heavy and light corundum bricks of points.

Different corundum bricks with different substrates are produced according to the use of different temperature environments, and in most cases, different grades of corundum bricks are made according to the indexes of the using manufacturers. Composite corundum bricks have brown corundum and silicon carbide composite bricks, corundum and silicon nit ride combination of composite bricks, as well as white corundum, plate corundum and mullite composite corundum mullite bricks, corundum mullite bricks there are lightweight, there is a big difference in bulk density, there are 1.5, 2.8-3.4 between the different volumes of corundum bricks; and chrome composite corundum refractory bricks, chrome corundum refractory bricks are generally used in the Waste incinerator lining.

Corundum bricks according to different aluminum content, there are 85-98% aluminum content between the content of more than 95% of corundum bricks have casting molding, in the glass kiln lining with more, the price is also quite expensive, mainly used in the bottom of the glass kiln to resist acid erosion. There are AZS corundum bricks, corundum mullite bricks and so on.

And corundum mullite bricks if lightweight, is produced according to the desired shape cut out, bulk density in general in about 1.5. Available in high temperature insulation layer, can also be used directly in the working layer, generally used in light kiln lining. For example, shuttle kiln liners and some light tunnel kilns.

Sintered zirconia corundum brick (hereinafter referred to as AZS brick) raw materials used for alumina and zircon, generally ZrO₂ content is controlled at 15% ~ 30%, the main crystalline phase composition of mullite, corundum and plagioclase zircon, in the raw material is very pure conditions, the glass phase content can be less than 5%, so the production of this type of products based on physical - chemical mainly Al₂O₃ and ZrSiO₄ solid-phase reaction between the reaction.

There are three main types of products in this series:

 

① Reaction-sintered AZS products, which are two-phase uniformly distributed microstructures composed of mullite and plagioclase zircon (with some t-ZrO₂). The irreversible reaction is also known as in situ reaction. The starting temperature of the reaction ranges from 1370 to 1420°C. The reaction is also known as in-situ reaction.

②Recombined AZS products are made from electrofused AZS by crushing, molding and sintering.

③ Zirconia-containing quartz series products. This series of products belongs to the simplest type of process in the broad sense of sintered AZS - sintered or electrofused mullite or corundum or calcined bauxite coarse particles with zircon in any proportion, plus a small amount of binding clay or other binding agent sintered. The firing temperature determines whether the zircon particles decompose completely, decompose slightly on the surface or do not decompose at all. Sintered zircon at 1650°C shows no decomposition, but the surface in contact with Al₂O₃ decomposes at less than 1500°C.

Al₂O₃-ZrSiO₄ solid-phase reaction

In the ZrO₂-Al₂O₃-ZrSiO₂ system, the Al₂O₃-ZrSiO₄ linkage is non-co-existing, and the following reactions take place between the two at about 1400 °C:

3Al₂O₃+2ZrSiO₄→ 3Al₂O₃•2SiO₂+2ZrO₂

The reaction products are tetragonal ZrO₂ and amorphous mullite, the latter being an important transition phase that tends to equilibrate at sub-solidus temperatures, and plagioclase zircon and mullite are obtained above 1450 °C.

Key Issues in the Preparation of Sintered AZS Products

The key issues in the preparation process of sintered AZS products are:

① Ensure that the reaction between ZrSiO₄ and Al₂O₃ is complete, the sintering is dense, and a uniform mullite-(corundum)-plagioclase zircon clinker is formed, with the glassy phase content not exceeding 5%.

② The alumina + kaolin dispensed into the clinker shall conform to the mullite composition.

③ The particle size gradation of the products shall be rationalized to ensure the maximum packing density.

④ The products are fully sintered to obtain the ideal microstructure. The production of high-quality sintered AZS products is more difficult, in a sense, the strict requirements of the control process, no less than the fusion casting products.

Properties of sintered zirconia corundum bricks

The high temperature mechanical properties of the sintered AZS products were good, as shown in the table.

Zinfon Refractory Technology Co.,Ltd

We are a refractory material supplier integrating R&D,production,construction,warehousing and commerce.

We are offering various magnesia and alumina refractories including both shaped and unshaped products, raw materials and related chemical products.

We are certified to ISO9001, ISO14001, ISO45001 and other national and local certifications as follows:

Send Inquiry Now