Refractory refers to inorganic non-metallic materials whose temperature is above 1580 Celsius refractoriness. Refractoriness means refractory cone sample in the absence of load cases, resistance to high temperature without melting down the softening temperature in Celsius. Refractories and high temperature technology accompanied appears roughly originated in the mid-Bronze Age. China Eastern Han Dynasty has been made to burn wood and porcelain kiln sager clay refractories. Early 20th century, the high-purity refractory, high density and ultra-high temperature product direction, while there has been complete without firing, small power consumption monolithic refractories and refractory fibers. Modern with the development of atomic energy technology, space technology, new energy technologies, high temperature, corrosion resistance, thermal shock resistance, erosion and other comprehensive excellent performance refractories has been applied. Refractory variety, usually divided according to the level of ordinary refractoriness refractory (1580 ~ 1770 Celsius), advanced refractories (1770 ~ 2000 Celsius) and grade refractory (above 2000 Celsius); divided by the chemical properties of acidic refractories, neutral and basic refractories. In addition, there are special occasions for refractories.
Silicon oxide as the main component to acidic refractory, commonly used silica brick and clay. Silica brick containing 93% silica siliceous products, its raw materials are silica, silica brick scrap, with its strong acid slag corrosion resistance, high softening temperature under load, the volume does not shrink after repeated firing, even a slight expansion; but its vulnerability to erosion of basic slag, thermal shock resistance is poor. Mainly used silica brick oven, glass melting furnaces, steel furnaces and other acidic thermal equipment. To fire clay brick as the main material containing 30% to 46% alumina, is a weak acid refractory, thermal shock resistance, corrosion resistance to acid slag has wide application.
Oxide, chromium oxide and carbon are main component in neutral alumina refractory. Containing more than 95% of alumina corundum products is a wider use of high-quality refractory materials. Chromium oxide as the main component of chromium slag bricks for good corrosion resistance, thermal shock resistance, but poor low temperature load deformation temperature. Carbon-carbon refractory bricks, graphite products and silicon carbide products, low coefficient of thermal expansion, high thermal conductivity, good heat resistance, vibration resistance, high temperature strength, resistance to acid and salt erosion, not metal and slag wetting, light. Widely used as a high-temperature furnace lining material, also used in petroleum, chemical autoclave liner.
Basic refractory magnesia, calcium oxide as the main component, is used magnesia brick. Magnesium containing more than 80% to 85% of the brick, alkaline slag and iron slag has good resistance, high refractoriness than clay and silica brick. Mainly used for open-hearth, basic oxygen furnace, electric furnace, high temperature and non-ferrous metal smelting equipment and some equipment.
Special occasions refractory oxide material has a high temperature, such as alumina, lanthanum oxide, beryllium oxide, calcium oxide, zirconium oxide, refractory material compounds, such as carbides, nitrides, borides, silicates and sulphides, etc.; temperature composite materials, mainly metal ceramics, high temperature inorganic coatings and fiber-reinforced ceramics.