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Mullite is an important refractory component, and common mullite refractory products include mullite bricks, silica mullite bricks, corundum mullite bricks and so on. Mullite series refractory bricks are widely used in high temperature industrial equipment and furnace lining.
Fireramo, as a leading refractory material supplier in China, in order to better help you understand mullite refractory material. We have compiled some of the most frequently asked questions about mullite, which are asked by customers from all over the world. We believe that after reading this article, you will also have a clear understanding of mullite refractory material.
What is mullite refractory?
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Mullite refractory is a type of refractory material with mullite as the main component. Mullite is a mineral composed of aluminum silicate, which has excellent heat resistance and chemical stability.
Natural mullite crystals are elongated needles and radial clusters, while mullite is formed when aluminum silicates are artificially heated. Mullite ores are used for the production of high-temperature refractories and as thermal barrier coatings in C/C composites.
Composition of mullite
Mullite refers to a group of minerals consisting of aluminum silicates, which are chemically composed primarily of aluminum silicate. It is a composite oxide consisting of aluminum-oxygen hexahedra and silica-oxygen tetrahedra.
In the crystal structure of mullite, a three-dimensional network is formed between each aluminum-oxygen hexahedron and each silica-oxygen tetrahedron by sharing oxygen atoms. This structure gives mullite a certain stability and special physical properties.
Properties of mullite
Mullite has a high melting point, high-temperature strength, low thermal expansion, excellent thermal shock resistance, high hardness and good chemical resistance, which makes it an excellent raw material for refractories.
Difference between mullite and alumina
Difference in chemical composition
Mullite: The chemical formula of mullite is Al₂SiO₅, mainly composed of aluminum silicate.
Alumina: The chemical formula of alumina is Al₂O₃, which is composed entirely of aluminum oxide.
Differences in crystal structure
Mullite: Mullite has a complex crystal structure that includes a three-dimensional network formed by shared oxygen atoms of aluminum-oxygen hexahedra and silica-oxygen tetrahedra.
Alumina: The crystal structure of alumina is a typical ionic crystal structure consisting of alumina cations (Al³⁺) and oxygen anions (O²-).
Differences in physical properties
Mullite: Mullite has a low coefficient of thermal expansion and excellent resistance to high temperatures, enabling it to maintain its structural stability in high-temperature environments. It also has a certain mechanical strength and hardness.
Alumina: Alumina has good heat resistance and a high melting point, and is able to maintain stability at high temperatures. It also has high hardness and resistance to abrasion.
Differences in fields of application
Mullite: Mullite is mainly used in high-temperature industrial fields such as refractory materials, high-temperature hearths, heat-insulating materials, etc. It is also used in the manufacture of insulating materials and ceramic products.
Alumina: Alumina is more widely used, it can be used in ceramics manufacturing, electronic devices and other fields. It is also used in the preparation of refractory materials, coatings, electrolytic aluminum and so on. It is the main raw material of aluminum refractory bricks, we commonly have high alumina bricks, 70 high alumina bricks and high alumina castables.
How is mullite formed?
The formation of mullite is related to metamorphism at high temperatures and mineral interactions. It is usually formed in metamorphic rocks at high temperatures, especially in the metamorphism of aluminosilicic and volcanic rocks.
Types of mullite refractories
Types of mullite refractories commonly include mullite bricks, silica mullite bricks, Fused mullite bricks, corundum mullite bricks, chrome mullite bricks, and mullite insulating bricks, among other refractories.
Fireramo offers high quality mullite refractory bricks.
Application of mullite refractory bricks
Mullite bricks: commonly used in the construction of industrial high-temperature kilns, such as smelting furnace, converter, electric arc furnace, etc., furnace lining.
Silica mullite bricks: widely used in the glass industry in the glass kiln, fiberglass casting and high temperature chemical reaction equipment.
Fusted mullite bricks: used as capacitor insulating materials in electronic devices, with good insulating properties and high temperature resistance.
Corundum mullite bricks: used in metallurgical industry for high-temperature hearth, glass industry for glass kiln and other scenes requiring high-temperature stability and abrasion resistance.
Chrome mullite bricks: commonly used in high temperature hearth in metallurgical industry, acid and alkali corrosion resistant environment in chemical equipment, etc.
Mullite insulation bricks: mainly used in high-temperature equipment insulation, such as high-temperature furnace chamber, heat treatment equipment, etc., can effectively reduce heat conduction and maintain temperature stability.
Specializing in refractory materials for over 20 years, we provide professional refractory solutions for the global high temperature industry.
