Refractoriness of not less than 1580 ℃ of a class of inorganic non-metallic materials. Refractory degree refers to the refractory cone specimen in the absence of load conditions, resistance to high temperature effect without softening the melting of the Celsius temperature. But only to the definition of refractories can not fully describe the refractory, and 1580 ℃ is not absolute. It is defined as materials that are allowed to be used in high temperature environments where physical and chemical properties are called refractory materials. Refractory materials are widely used in the metallurgical, chemical, petroleum, machinery manufacturing, silicate, power and other industrial fields, the largest in the metallurgical industry, accounting for 50% of the total output of 60%.
Refractory materials used in iron and steel, nonferrous metals, glass, cement, ceramics, petrochemical, machinery, boilers, light industry, electricity, military and other national economy in all areas, is to ensure that the production and operation of the industry and essential technical development essential materials, In the development of high temperature industrial production plays an irreplaceable important role.
Refractory materials variety, use different, it is necessary to scientific classification of refractories, in order to facilitate scientific research, rational selection and management. There are many methods of classification of refractories, including chemical classification, chemical composition classification, production process classification, material morphology classification and other methods.
Frequently used special materials are AZS brick, corundum brick, directly combined with magnesia-chrome brick, silicon carbide brick, silicon nitride combined with silicon carbide brick, nitride, silicide, sulfide, boride, carbide and other non-oxide refractories ; Calcium oxide, chromium oxide, alumina, magnesium oxide, beryllium oxide and other refractories. Frequently used insulation refractories are diatomite products, asbestos products, thermal panels and so on. Frequently used unshaped refractories are filled charge, ramming material, castable, plastic, refractory mud, spray feed, casting material, paint, light refractory castable, gun mud and so on.
According to the degree of compactness and shape of the product, there are sintering method, casting method and melt injection method. Sintering method is part of the raw materials pre-burned clinker, broken and sieved, and then by a certain ratio and raw materials mixed, after molding, drying and firing. The purpose of raw materials is to burn the water, organic impurities, sulfate decomposition of the gas burned to reduce the sintering of products to ensure the accuracy of the product size. The raw material also needs to be sieved after crushing and grinding, since the blanks are graded with powders of different particle sizes to ensure that the most compact deposits are obtained.
In order to homogenize the ingredients and particles of various raw materials and clinker, kneading is carried out while the binder is added to enhance the binder bonding strength. Such as aluminum silicate billet to join the combination of clay, magnesia billet into the sulfite pulp waste, silicate billet powder and so on. According to the amount of water content of the blank, can be semi-dry molding (about 5% moisture), plastic molding (about 15% moisture) and grouting molding (about 40% moisture). And then dried and fired. Casting method is the raw materials through the mixing process and fine grinding and other processes, melting at high temperatures, direct casting, cooling crystallization, annealing products. Such as cast mullite tiles, corundum bricks and magnesia bricks. Their body is dense, high mechanical strength, high temperature structural strength, good slag resistance, the use of the range continue to expand. The melt-blown method is a method in which a batch is melted and then blown into high-pressure air or superheated steam to disperse it into fibers or hollow spheres. Products are mainly used for light refractory, insulation materials. In addition, can also be made of powder or granular amorphous refractory, temporary use tar, asphalt, cement, phosphate, sulfate or chloride and other bonding agent bonding, without molding and sintering and direct use.