Refractory materials refer to inorganic non-metallic materials of which the refractoriness is more than 1500 ℃. Refractories materials are widely used in the metallurgy industry, chemical industry, petroleum industry, and machinery manufacturing, etc. Refactory material can be classified into ordinary refractory, advanced refractory, and super refractory, based on the refractoriness. And according to the chemical properties, refractory materials can be classified into acid refractory, neutral refractory, and alkaline refractory.
The main component of the acid refractory is silicon oxide, and the common bricks are silica bricks and fireclay bricks. The former contains 94% of silicon oxide, and take the silica as raw materials. Such bricks are featured with strong acidic slag erosion resistance, and high refractoriness, being widely used in the coke oven, glass furnace, and acid steel making furnace, etc. while the latter is mainly made of fireclay, plus 30%-46% of alumina. Such bricks are weak acid refractory materials, being featured with good thermal shock resistance, and acid resistance.
Neutral refractory materials contain alumina, chromium oxide and carbon. Corundum products, chrome bricks and carbon refractory materials are common types of such materials. Corundum refractory materials are high quality refractory material, which contain alumina more than 95%. Chrome bricks are used as the insulation bricks. And carbon refractory materials can be classified into carbon bricks, graphite products, and silicon carbide products, being featured with low thermal expansion coefficient, good thermal conductivity, good thermal shock resistance, high strength at high temperature, and anti-acid and alkali performance.
As for the alkaline refractory materials, such products is made of magnesium oxide and calcium oxide. The most commonly used products are magnesite bricks, which contain magnesium oxide about 80%-85%，with characters of alkaline slag and iron slag resistance, being widely used in the open hearth furnace, electric furnace, and non-ferrous metal smelting equipment, etc.
The most commonly used refactory materials are shaped refractory, unshaped refractory and insulation refractory.
Shaped refractory materials are refractory bricks, such as AZS refractory brick, high alumina brick, magnesia brick, fireclay refractory brick, silicon brick, corundum brick, direct-bonded magnesia-chrome brick, silicon-carbide brick, and insulation brick, etc.
Unshaped refractory materials are also called monolithic refractory, which are made of power, aggregate and binder, being used directly without firing, such as ramming mass, plastic, castable, pouring materials, gunning mass, and coating materials, etc.
And the insulation refractory materials can be classified into refractory blanket, refractory board, refractory rope, and insulation refractory brick, such as alumina bubble brick, mullite insulating brick, and diatomite insulation brick, etc.
There are great varieties of refra products with different purposes, so, it is necessary to classify such materials, in order to research, use and manage refractory materials scientifically.
