Lightweight refractory bricks have low compressive strength, poor slag resistance, and poor thermal shock resistance, so they cannot be in direct contact with molten glass or flames. However, because of its internal porous structure, it has thermal insulation properties and is widely used for thermal insulation. There are five main materials for lightweight insulating refractory bricks for glass kilns, and their characteristics are as follows:
(1)Lightweight clay insulation bricks
Lightweight clay insulation bricks are insulating refractory products made of refractory clay as the main raw material, with an A1203 content of 30%~48%*. Its production process adopts burnout additive method and foam method. Using refractory clay, floating beads and refractory clay clinker as raw materials, adding binder and sawdust, through batching, mixing, shaping, drying and firing, a product with a physical density of 0.3~1.5g/cm3 is produced. Lightweight clay insulation bricks have a wide range of uses. They are mainly used as insulation layer refractory materials in various industrial kilns without contact with melts and corrosive gases. The use temperature is 1200-1400℃.
(2)Lightweight silica insulation bricks
Lightweight silica insulation bricks are insulating and refractory products made of silica as the main raw material with a Si02 content of not less than 91%. The volume density of lightweight silica insulation bricks is 0.9~1.1g/cm3, the thermal conductivity is only half that of ordinary silica bricks, and it has good thermal shock resistance. Its load softening starting temperature can reach 1600°C, which is much higher than that of clay insulation bricks. Hot Bricks. Therefore, the maximum operating temperature of silica insulation bricks can reach 1550℃. It does not shrink at high temperatures and even expands slightly.
(3) Lightweight alumina insulation bricks
Lightweight alumina insulation bricks are fire-insulating products made of fused corundum, sintered alumina and industrial alumina as the main raw materials. There are two production processes: foam method and burnout additive method. Alumina insulation bricks are produced by foam method. The clinker is ground and mixed with binder and foaming agent to prepare slurry, which is poured into L and fired at 1350~1500℃. The product has high refractory resistance and good thermal shock resistance, and is often used as a high-temperature insulation layer for kilns. The use temperature is 1350~1500°C, and the use temperature of high-purity products can reach 1650~1800°C.
(4)Lightweight mullite insulation bricks
Lightweight mullite insulating bricks are insulating and refractory products made of mullite as the main raw material. Mullite insulation 5 has high temperature resistance, high strength, low thermal conductivity and can be directly exposed to flames. It is suitable for the dense lining of various industrial furnaces.
(5) Diatomite bricks
Compared with other insulation bricks with the same bulk density, diatomite bricks have smaller thermal conductivity. The reason is that the pores in diatomite are very small and have a good shielding effect on heat.
The operating temperature of diatomaceous earth bricks varies with purity. The use temperature of products made of general diatomite is generally below 1000°C.
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