Fused Cast AZS Exudation And Glass Defects

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Fused cast AZS block is the most widely used refractory material in the
demanding areas. It is thought as the leading cause of knot and cord defects.
Fused cast AZS exudation in glass contact is the main cause of impaired
performance of AZS under particular working conditions.

The main crystal phase of Fused cast AZS consists of corundum, baddeleyite and
glass phase. The glass phase can reduce the expansion or shrinkage of ZrO2
within the above temperature range and prevent cracking. However, the glass
phase is easy to be corroded and cause corrosion of the fused cast AZS and glass
defects.

Fused cast AZS exudation exhibits a shiny "wet looking" appearance at the
surface of blocks during heat-up process and beginning of a furnace campaign.
This situation tends to stabilize all along the campaign life, with a generally
moderate dripping of a viscous glassy phase into the smelted glass.

Fused cast AZS exudation at high temperatures, can lead to the formation of
defects in the glass, especially during furnace start-up. It is only a
short-term cause of glass defects. Fused cast AZS exudation from a glass contact
surface is not very visible than that in the superstructure.

In the glass furnaces, a portion of the glass phase of fused cast AZS block
exudes onto the superstructure surface during furnace heat-up, until the furnace
has achieved stable temperature profile. The exuded glass, often containing
small zirconia crystals, tends to run down into the glass bath. This is a major
concern to glass producers since this glassy phase often causes defects, such as
viscous knots and stones.

To solve this problem, low exudation fused cast AZS has been developed. With
modification of chemical compositions and glass phase, it offers low exudation
level and maintains all other positive characteristics of fused cast AZS.

Sunrise offers various refractory materials for glass furnaces including fused
cast AZS, silica brick, fireclay brick, high alumina brick, silimanite brick,
mullite brick, etc..


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