Glass defects that may be caused by refractory bricks for glass kilns

Glass defects produced by refractory bricks may have the following 3 types:

1. Stones

When larger particles of refractory bricks for glass kiln fall off into the glass melt and cannot be completely dissolved by the melt, "stones" appear in the glass. Larger particles will settle to the bottom of the pool. Insoluble substances such as ZrO2 can also be dispersed into very small particles.

The alkali in the glass will react with alumina-containing refractory bricks to form feldspar-like substances. Flakes come off due to differences in thermal expansion. After falling off, new flakes are formed to cause harm. The unsintered particles in the rammed material may also enter the glass and form stones.

2. Bubbles

All organic impurities attached to the surface of refractory bricks will be burned to produce bubbles. Some inorganic building materials also have a tendency to generate air bubbles at the beginning. In addition, the air expelled from the holes of the refractory bricks can also cause air bubbles. Carbonaceous impurities are always the source of bubbles.

Metallic iron itself has no tendency to create bubbles, whereas the carbon contained in it does. Substances with redox potential also generate bubbles due to changes in the oxidative conditions in the melt. Zirconium bricks also tend to generate air bubbles in the initial stage of use. But after the action of the alkali in the glass improves the quality, the bubbles are no longer generated.

3. Defects formed indirectly

Alkali and Al2O3-containing materials in the glass combine with feldspar-like substances. In a certain temperature range, this substance cannot be completely dissolved and leaves "stones". The effect with KZ-brick is similar. Alumina may dissolve or semi-dissolve, leaving ZrO2 as "stones". Aggressive components of the glass may dissolve the SiO2 in the zircon article leaving ZrO2 stones. If the particles are large enough, stones can appear in the glass. The particles described above are also produced on eroded checker bricks. The passage of combustion air through the checker brickwork may blow them (parts of the checker bricks, damaged refractory brick parts or their constituents) into the melt and cause calculus. Stones may also form from refractory bricks falling from the kiln superstructure or dome.




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