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Types and properties of refractories
Jan 03, 2019

1. What is refractory?

A refractory material generally refers to an inorganic non-metallic material having a refractoriness of 1580 ° C or more. It includes natural ores and various products made through certain processes according to certain purposes. It has certain high temperature mechanical properties and good volume stability, and is a necessary material for various high temperature equipment. It is very versatile.

Second, the type of refractory materials?

1. Acid refractory material generally refers to refractory material with SiO2 content greater than 93%. Its main feature is that it can resist the erosion of acid slag at high temperature, but it is easy to react with alkaline slag. Silica bricks and clay bricks are commonly used for acid refractories. Silica brick is a siliceous product containing more than 93% of silicon oxide. The raw materials used are silica, waste silicon brick, etc., which have strong resistance to acid slag erosion, high load softening temperature, no shrinkage after repeated calcination, and even slight expansion; However, it is susceptible to corrosion by alkaline slag and has poor thermal shock resistance. Silica bricks are mainly used in thermal equipment such as coke ovens, glass melting furnaces, and acid steelmaking furnaces. Clay bricks are mainly made of refractory clay and contain 30% to 46% of alumina. They are weakly acidic refractories, have good thermal shock resistance, and are resistant to acid slag.

2. Alkaline refractory materials generally refer to refractory materials containing magnesium oxide or magnesia and calcium oxide as main components. These refractories have high refractoriness and are resistant to alkaline slag. For example, magnesia brick, magnesia chrome brick, chrome magnesium brick, magnesium aluminum brick, dolomite brick, forsterite brick, and the like. Mainly used in alkaline steelmaking furnaces, non-ferrous metal smelting furnaces and cement furnaces.

3. Aluminosilicate refractory refers to refractory material with SiO2-Al2O3 as the main component. According to its Al2O3 content, it can be divided into semi-silica (Al2O3 15~30%) and clay (Al2O3 30~48%). , high aluminum (Al2O3 is greater than 48%) three categories.

4. Melt-casting refractory material refers to a refractory product having a certain shape after being melted at a high temperature by a certain method.

5. Neutral refractory refers to refractory materials that are not easily reacted with acidic or alkaline slag at high temperatures, such as carbon refractories and chrome refractories. Some also attribute high alumina refractories to this category.

6. Special refractory materials are new inorganic non-metallic materials developed on the basis of traditional ceramics and general refractory materials.

7. Unshaped refractory material is a mixture of refractory aggregate and powder, binder or additional admixture. It can be used directly or with appropriate liquid. The amorphous refractory material is a new refractory material which is not calcined and has a refractoriness of not less than 1580 °C.

3. What are the refractory materials that are often used?

Commonly used refractory materials are silica bricks, semi-silica bricks, clay bricks, high alumina bricks, magnesium bricks, and the like.

Special materials commonly used are AZS bricks, corundum bricks, direct combination of magnesia chrome bricks, silicon carbide bricks, silicon nitride bonded silicon carbide bricks, non-oxide refractories such as nitrides, silicides, sulfides, borides, carbides, etc. Refractory materials such as calcium oxide, chromium oxide, aluminum oxide, magnesium oxide, and antimony oxide. Frequently used insulating refractories are diatomite products, asbestos products, insulation panels, and the like.

Commonly used amorphous refractories are refractory materials, refractory ramming materials, refractory castables, refractory plastics, refractory clay, refractory spray materials, refractory projection materials, refractory coatings, lightweight refractory castables, gun mud, ceramic valves. Wait.

Fourth, the physical properties of refractory materials include those?

The physical properties of refractory materials include structural properties, thermal properties, mechanical properties, performance properties and workability. The structural properties of refractories include porosity, bulk density, water absorption, gas permeability, pore pore size distribution, etc. The thermal properties of refractories include Thermal conductivity, coefficient of thermal expansion, specific heat, heat capacity, temperature coefficient, thermal emissivity, etc. The mechanical properties of the refractory include compressive strength, tensile strength, flexural strength, torsional strength, shear strength, impact strength, wear resistance, creep, bond strength, modulus of elasticity, and the like.

The refractory properties include refractoriness, load softening temperature, reheating line change, thermal shock resistance, slag resistance, acid resistance, alkali resistance, hydration resistance, CO corrosion resistance, electrical conductivity, oxidation resistance Wait.

The workability of the refractory material includes consistency, slump, fluidity, plasticity, cohesiveness, resilience, cohesiveness, hardenability, and the like.

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