The service life of refractory materials is mainly affected by erosion conditions in addition to the performance of refractory materials. When the same refractory material is used in different parts, the erosion conditions are different, so the use effect is also different. For example, when β-corundum fused refractory is used for the side wall of the upper structure of the horizontal flame pool furnace, it is seriously eroded and damaged near the feeding port where the temperature is not high, but the erosion is very slight when it is used at a high temperature far from the feeding port. It is not as imagined that the higher the temperature, the more severe the erosion. This is mainly due to the fact that erosion is not determined by the temperature alone. In the above case, the refractory material is attacked by different kinds and different amounts of chemical attacking agents in addition to the temperature factor. The fused β-corundum brick near the feeding port is mainly eroded by the dust of the batch material, and this corrosive agent has a great destructive effect on the β-corundum brick. At high temperatures far from the feeding port, the corrosive agent is mainly alkaline gas. Beta-corundum bricks are very resistant to alkaline gases.
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The erosion factors are mainly considered from the following aspects: a. temperature conditions; b. chemical erosion conditions; c. physical erosion conditions; d. time conditions.
These four conditions cannot exist alone when the refractory is eroded. It must be a combination of several conditions. The simplest simple heating process is also a synthesis of temperature conditions and time conditions. This includes the heating or cooling process, the maximum temperature and its holding time. Chemical attack conditions also include a lot of content. In addition to the type and quantity of etchants, temperature, duration and frequency have a great impact on chemical attack conditions. The same is true for physical attack conditions, which often co-exist with physical attack and chemical attack. The combined effect of these four conditions in a glass pool furnace determines the rate at which the refractory is eroded. Moreover, under the action of these erosive conditions, the damage of the refractory material will also contaminate the glass, which directly affects the quality of the glass.
What are the main types of physical erosion of glass tank kiln refractories?
Physical erosion has a great relationship with time and temperature. The most important physical erosion is the scouring effect of the glass flow and the gravitational effect of the refractory load.
In high temperature regions, the scouring action of the molten glass stream multiplies the chemical attack rate. In the low temperature area, the chemical attack is very small, and the physical attack is mainly caused by liquid scouring. In the high temperature zone of the melting pool, the viscosity of the glass flow is low and the liquid flow is strong. Especially after the use of electric boosting and bubbling, the flow is more intense. The combination of strong scouring and chemical attack can cause great damage to refractory materials.
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Gravity damage caused by load mainly occurs in the regenerator checkered bricks. With the advancement of pool furnace technology, the height of the regenerator has been continuously increased, and the self-weight of the lattice body has a great pressure on the lower lattice bricks and the grate. will cause the entire lattice to collapse.
The contamination of glass by refractory materials is as follows:
The composition of the refractory material and the composition of the reaction product with glass are different from the composition of glass. Such different components can be in solid, gas or liquid phase. Defects produced by refractory materials mainly include the following three types in appearance: stones and streaks, coloring, and bubbles.
Contamination from refractory materials is in most cases the result of erosion of the refractory material. The more severely the refractory is eroded, the more glass defects are created. There are three kinds of stones caused by refractory materials: one is the original crystal phase of the refractory material, the second is the metamorphic crystal formed by the reaction between the refractory material and the glass, and the third is the recrystallization after the refractory material is melted. Streaks produced by refractory materials are often co-existed with stones. Some stones crystallize out in the streaks, and some streaks are caused by the melting of the stones. Another kind of streak without stones, which is mostly caused by the glass phase in the refractory. Stones and streaks produced by refractory materials are mostly the result of a combination of physical and chemical erosion.
Since the refractory material contains Fe₂O₃, Cr₂O₃ and other substances, these are strong colorants. Therefore, after the refractory is eroded, these oxides enter the glass and cause coloration.
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There are two main types of bubbles caused by refractory materials. One is that the refractory material itself has pores, and the gas in it is replaced by the glass. The other is due to the bubbles generated by the reaction between glass and refractory materials. The former is caused by physical action, and the latter is the result of the combined action of physical erosion and chemical erosion.
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