refractory

Silica brick belongs to acid refractories, mainly consisting of tridymite, cristobalite and a small amount of residual quartz and glass phase. It has good resistance to acid slags.

The raw material for silica brick production is silica. The silica has a high content of SiO2 and high refractoriness. The most harmful impurities are Al2O3, K2O, Na2O, etc. They can seriously reduce the refractoriness of the silica brick. Silica brick is made of silica containing more than 96% SiO2 , with addition of mineralizing agent (such as iron scales, lime) and binder (such as molasses, sulfite pulp waste), by kneading, shaping, drying and calcining.

Silica brick has a high softening temperature under load up to 1640 ~ 1670 ℃ and good volume stability in long term use. The mineralogical composition of silica brick mainly consists of tridymite and cristobalite, as well as a small amount of quartz and glass phase.

Tridymite, cristobalite and residual quartz has a big volume change due to crystal transformation at low temperatures. Therefore, the thermal stability of silica brick is poor at low temperatures. During the use, the silica brick should be heated and cooled slowly in order to avoid cracks. It should not be used in the furnaces that have rapid temperature change below 800℃.

The property and process of the silica brick is closely related to the crystal transformation of SiO2. Therefore, the true specific gravity is an important quality indicator of silica brick. Generally it should be under 2.38. For the high quality silica brick, it should be under 2.35. The low true specific gravity means the quantity of tridymite and cristobalite is high and the amount of residual quartz is small. Therefore, the residual linear expansion is small and the strength decreases.

SiO2 has seven crystalline variants and a amorphous variant. These variants can be divided into two categories. the first category include quartz, tridymite and cristobalite. Their crystal structure is very different and the transformation between them is very slow. The second category are subspecies of the variants above, α,β and γ. They have similar structures and can be transformed to each other quickly.

Zhengzhou Sunrise is a refractory material supplier from China, offering high quality refractory materials for glass furnaces, including fused cast AZS block, fused cast alumina block, fused cast high zirconia block, mullite brick, zircon brick, alumina bubble brick, magnesia brick, sillimanite brick, corundum brick, low porosity fireclay brick, high alumina brick, all kinds of glass furnace ramming masses, etc..

With the development of technology, a variety of zirconia refractories have been developed. Recently, zirconia refractory, as a new type of refractory, has been widely used in the metallurgy, construction and chemical industry.

ZrO2 is widely used in the refractory for the glass industry, metallurgy industry, construction industry and chemical industry, because it has high melting temperature, good thermal shock resistance and high chemical stability. Zirconia refractories are mainly used in demanding areas of glass furnaces such as the superstructure, the melting zone, the sidewall and the throat.

The main types of zirconia refractories include zircon bricks, dense zircon bricks, fused cast AZS block, fused cast zirconia mullite block and bonded again AZS bricks.

In the metallurgical industry, based on the materials, zirconia refractories can be divided into zirconite refractory, zirconia refractory, aluminum zirconium refractory, calcium zirconate refractory, zirconium diboride refractory and modified zirconia refractory.

Zirconite refractory features high temperature performance, good resistance to acid slags, good corrosion resistance, low thermal expansion coefficient and good thermal shock resistance. It can be used in the ling of the ladle.

The raw materials for zirconia refractories include zirconite refractories in various sizes and various zirconia materials. The molding methods include slurry casting method, machine pressing method and isostatic pressing method. Different molding methods have different requirements for the grains of raw materials. Products made in different methods have different performance and applications, but all have the feature of good resistance to high temperature and corrosion.

Aluminum zirconium refractory is developed based on the aluminum carbon refractory. It is mainly used in the ladle, tundish, slide gate brick, long nozzle, stopper and outlet. Compared to aluminum carbon refractory, it has better resistance to oxidation, thermal shock and corrosion, higher strength and longer service life.

Zhengzhou Sunrise is a refractory material supplier from China, offering high quality refractory materials for glass furnaces, including fused cast AZS block, fused cast alumina block, fused cast high zirconia block, mullite brick, zircon brick, alumina bubble brick, magnesia brick, sillimanite brick, corundum brick, low porosity fireclay brick, high alumina brick, all kinds of glass furnace ramming masses, etc..

Fused cast AZS block is the most widely used refractory material used in the glass furnace. Its quality and performance is important for the service life of the glass furnace and the glass quality. To select the right fused cast AZS, it is important to know how to judge its quality.

In the corner block, dam block, bubble block and throat, fused cast AZS 41# is used. The bottom part of the brick should not have shrinkage cavity and the numbers of the apparent pores larger than 2mm should be less than 20/m3.

Cracks are not allowed in the bubble block and throat block. The top part of the sidewall does not allow the existence of defects. These requirements are very important, or it will affect the life of the bricks.

The color of fused cast AZS block is generally white or light yellow. Its color can tell the content of impurities, such as the content of the carbon. If the brick is blue, it may contain a high content of carbon. This kind of brick cannot be used, or it will reduce the service life of the furnace. If the surface of the brick has blue spots, there may be iron inside it. This kind of brick should be avoided too.

The content of glass phase should be controlled well. It it is too high, the glass phase may extrude at high temperature, which will reduce the service life of the furnace and pollute glass liquid.

Besides those mentioned above, there are still many other factors that should be paid attention to. The problems fused cast AZS encounters in use have great relationship to its quality. So it is important to select high quality bricks.

Zhengzhou Sunrise is a refractory material supplier from China, offering high quality refractory materials for glass furnaces, including fused cast AZS block, fused cast alumina block, fused cast high zirconia block, mullite brick, zircon brick, alumina bubble brick, magnesia brick, sillimanite brick, corundum brick, low porosity fireclay brick, high alumina brick, all kinds of glass furnace ramming masses, etc..