Composition and Application of Refractory Castable
Refractory refers to the temperature of the cone sample of refractory castable in the absence of a load, against the high temperature effect without softening and melting. Refractory castable and high temperature skills appear, roughly originated in the middle of the Bronze Age. During the Eastern Han Dynasty, clayey refractory castables were used as kiln materials and saggers for firing porcelain. At the beginning of the 20th century, refractory castables were developed to high purity, high density and ultra-high temperature products. At the same time, monolithic refractory castables and refractory fibers with no need for firing and low energy consumption appeared. Contemporary, with the development of orchard energy skills, space skills, and new resource skills, refractory castables with comprehensive and high-quality functions such as high temperature resistance, erosion resistance, thermal vibration resistance, and erosion resistance have been applied.
Composition and application of refractory castables: there are many varieties of refractory castables, which are usually divided into regular refractory castables (1580~1770 ℃), advanced refractory castables (1770~2000 ℃) and refractory castables (above 2000 ℃) according to their high and low refractoriness. According to chemical characteristics, it is divided into acidic refractory castables, neutral refractory castables and alkaline refractory castables. In addition, there are refractory castables for special sessions.
Acidic refractory castables are composed of silicon as an important component, and silica bricks and clay bricks are commonly used. Silica brick is a siliceous product containing more than 93% of compound silicon. The raw materials used are silica, waste silica brick, etc. It has strong corrosion resistance to acidic slag, high temperature under load softening, no reduction in volume or even slight expansion after repeated calcination. However, it is susceptible to corrosion by alkaline slag and has poor thermal vibration resistance. Silicon brick is important for coke oven, glass furnace, acid steelmaking furnace and other thermal facilities. Clay brick with refractory clay as an important raw material, containing 30% to 46% of the compound aluminum, is a weak acid refractory castable, good thermal vibration resistance, corrosion resistance to acid slag, application in depth.
The neutral refractory castable is composed of aluminum, chromium or carbon as an important component. Containing more than 95% of the compound aluminum corundum products is a wide range of high-quality refractory castable. The corrosion resistance of chromium brick to steel slag is good, but the thermal vibration resistance is poor, and the temperature is low. Carbonaceous refractory castables have carbon bricks, graphite products and silicon carbide products. Their thermal expansion parameters are very, very low, high thermal conductivity, good heat resistance and vibration performance, high high temperature intensity, corrosion resistance to acid and alkali and salt, and are not affected by metal and slag. Deeply used as high temperature furnace lining material, also used as petroleum, chemical autoclave lining.
Alkaline refractory castable to compound magnesium, compound calcium as an important component, the usual is magnesium brick. Magnesia brick containing more than 80% ~ 85% of magnesium compound has very good counterbalance to alkaline slag and iron slag, and its fire resistance is higher than clay brick and silica brick. Important for the furnace, blowing oxygen converter, electric furnace, non-ferrous metal metallurgy facilities and some high temperature facilities.
In the special field application of refractory castable with high temperature compound materials, such as compound aluminum, compound lanthanum, compound beryllium, compound calcium, compound zirconium, refractory oxide materials, such as carbides, nitrides, borides, silicides and sulfides; high temperature composite materials, important metal porcelain, high temperature inorganic coating and fiber reinforced porcelain.