Fused Cast Low-Leakage Refractories

Home » Refractories » Fused Cast Refractories » Fused Cast Low-Leakage Refractories

Fused cast low-leakage refractories are supposed to be a new AZS product for the high-end market of glass furnaces. The main component of them is fused alumina-zirconia-silica, which contains 36% ZrO2 and a lower silicate phase (14%). It has very low leakage and quite strong resistance to alkaline attacks, carry-over, and creep.

With the efforts in recent years, lots of Chinese enterprises already have been capable of commercial production of these products. The capability has gradually been developed and applied in the glass industry.

Fused Cast Low-Leakage Refractories

Application of the Fused Cast Low-Leakage Refractory

Low-leakage series are widely used in shaped products for high-end glass furnaces, such as fields of optical glass, high alumina glass, TFT-LCD, borosilicate glass, etc. They can be used on the parts which have strict requirements for high-temperature performance and glass phase leakage pollution, like a crown of the oxygen-fuel glass furnace, top spaces of refiner and doghouse crown, etc.

Characteristics of the Fused Cast Low-Leakage Refractory

The core of the low-leakage series is the low introduction of Na2O, which makes the structure of refractory materials with an effect of the lower glass phase. Traditional fused cast zircon-corundum refractory is composed of baddeleyite, corundum, and sodium aluminosilicate glass phase. And glass phase can bring effects of fluxing, relaxation annealing stress, and transformation stress. Its existence sharply reduces the occurrence rate of cracks in materials and improves the yield of refractory materials. However, the existence of the glass phase completely weakens the corrosion resistance of refractory. Especially in high-temperature conditions, the leakage of the glass phase is a potential risk of polluting glass.

The glass phase exudation is one of the important indicators to evaluate the performance of fused cast AZS refractory products. The exudation of the glass phase will destroy the structure of the brick and affect its lifespan. When exuding, bubbles will be released, and stones that are insoluble in glass may be produced, which will seriously affect the quality of the glass.

Fused Cast Low-Leakage Refractories

Development for Fused Cast Low-Leakage Refractory

For the fused cast low-leakage refractory used in the superstructure of the glass furnace, according to the different parts of use, it is mainly affected by alkali vapor, batch dust, and upper brick flowing matter (such as silicon rhodamine). At high temperatures, the glass phase in the brick seeps out on the surface of the brick, and the alkali vapor or alkali component in the batch dust is combined to reduce the viscosity and flow and drip into the glass liquid, causing pollution. At this time, the surface of the exposed brick is invaded by the subsequent alkali component, A120 is dissolved, the skeleton structure of the brick is destroyed, and the clinozircon crystal phase (Zr0) will be wrapped in the continuous glass phase exuding and flow and drip into the glass liquid to form stones.

The above process is carried out continuously and in a cycle. At this time, when the silica brick used in the upper part (such as large silicon brick) is abnormally eroded, the reactants generated will flow down from the surface of the AZS fused cast brick, so that the exuded glass phase or surface reaction layer is washed away and more likely to flow into the glass liquid to cause pollution.

Fused Cast Low-Leakage Refractories
Fused Cast Low-Leakage Refractories

Due to the development of glass kiln technology, the increase in kiln space temperature makes the above erosion process intensify. As mentioned above, the encroachment and contamination of the glass liquid in the glass furnace used in the superstructure are closely related to the exudation of the glass phase in the brick. The exudation performance of the glass phase is affected by the quantity and quality of the glass phase, and in fused cast AZS, SiO2 constitutes the main body of the glass phase and directly determines the number of glass phases.NazO affects the viscosity of the glass phase, and if the NaO content is large, the viscosity of the glass phase is small, the softening is fast at high temperatures, and it is easy to exude. Therefore, reducing SiO and NaO content can reduce the number of glass phases, improve the quality of the glass phase, and thus reduce the amount of glass phase exudation.

customer visit

We have determined multiple ingredient combinations, first in a small test electric furnace for quality evaluation, and then in the manufacturing furnace to confirm the manufacturing conditions such as sand structure, melt casting, insulation annealing, etc., as well as the pass rate and defects. The chemical composition range was finalized.

  • In the fused cast low-leakage refractory, due to the reduction of SiO2 and Na2 content, the content of the glass phase is reduced, and the quality of the glass phase is improved, so the glass exudation amount is greatly reduced.
  • Fused cast low-leakage refractory is more suitable for the superstructure of glass furnaces due to the improvement of glass phase exudation performance, especially for high-grade glass furnaces such as high-quality float glass, large glass shells, and liquid crystal glass.
  • With the rapid development of glass furnace technology, especially the gradual promotion of oxy-fuel furnaces, fused cast low-leakage refractory will have more and more broad prospects.
Fused Cast Low-Leakage Refractories
WhatsApp Message