Refractory composition

Acid refractories are mainly composed of silica, commonly used are silica bricks and clay bricks. Silica bricks are silicon products containing more than 94% silicon oxide. The raw materials used are silica, waste silica bricks, etc. Their acid-resisting slag has strong erosion resistance, and the softening temperature of the load is high. The volume does not shrink after repetitive calcination and even slightly expands. However, it is vulnerable to alkaline slag and has poor thermal shock resistance. Silicon bricks are mainly used in coke ovens, glass melting furnaces, acid steelmaking furnaces and other thermal equipment. The clay brick is mainly made of fire-resistant clay, contains 30% to 46% of alumina, is a weakly acidic refractory material, is good in resistance to thermal vibration and refractories, has corrosion resistance to acid slag, and is widely used.

Neutral refractories are mainly composed of alumina, chrome oxide or carbon. The corundum product containing more than 95% alumina is a kind of high-quality refractory material with wide application. Chromium bricks with chromium oxide as the main component have good corrosion resistance to steel slag, but have poor thermal shock resistance and low load deformation temperature at high temperature. Carbonaceous refractories are carbon bricks, graphite products and silicon carbide products, which have a low coefficient of thermal expansion, high thermal conductivity, good thermal shock resistance, high temperature strength, resistance to acid and alkali, and salts, especially weak acids and bases. Better resistance, free from metal and slag, light weight. Widely used as high-temperature furnace lining material, also used as oil, chemical industry autoclave lining.

Basic refractory materials are mainly composed of magnesium oxide and calcium oxide. Magnesia brick is commonly used. Magnesium oxide bricks containing 80% to 85% of magnesium oxide have good resistance to alkaline slag and iron slag, and have higher refractoriness than clay bricks and silica bricks. Mainly used in open hearth, oxygen blowing furnace, electric furnace, non-ferrous metal smelting equipment and some high temperature equipment.

Refractory materials used in special applications include high-temperature oxide materials such as alumina, yttria, yttria, calcia, zirconia, etc., refractory compound materials such as carbides, nitrides, borides, silicides, and sulfides. Etc.; high-temperature composite materials, mainly cermets, high-temperature inorganic coatings and fiber-reinforced ceramics.