The characteristics of corundum for refractories mainly include these features:
1. High strength and wear resistance;
2. Erosion and infiltration of acid-resistant slag: The main crystal phase of all types of corundum is a-Al2O3, which has good resistance to acid slag erosion and penetration. The slag produced during the ironmaking process is generally acidic slag, with higher SiO2 content and lower CaO content. The ironmaking industry generally uses Al2O3-based refractories as the inner lining, such as the high-alumina brick of the blast furnace body. The Al2O3-SiC-C refractories (poured and ramming) of the iron-gathering ditch. Artillery (Al2O3-SiO2-SiC) -C quality). Al2O3-SiC-C refractories (castables, refractory bricks, etc.) for ladle and torpedo.
3. Variety of materials and properties: The main crystal phase of corundum is a-Al2O3, which can be compounded with many oxides and non-oxides, improving some of its own properties, such as thermal shock resistance, resistance to slag (acidity or alkalinity). ) Erosion etc. Composited with SiO2 to form corundum mullite refractories, compounded with MgO to form corundum-spinel refractory, and compounded with zircon sand (ZrO2 and SiO2) to form Al2O3-SiO2-ZrO2 refractories, with silicon carbide and Carbon composite forms Al2O3-SiC-C refractories, etc.;
4. The diversity of the combination of methods, corundum and various binders compatibility is good, you can use a variety of bonding methods, such as high-temperature sintering, low temperature bonding, etc., can give the material different characteristics.
Corundum is mainly divided into two types of refractories: styling products and indefinite products.
Stereotype products mainly include:
1. Corundum Refractory Products: Al2O 398% or more, since the combination of solid-phase sintering of high-quality corundum products, the main phase is corundum, there are a small amount of mullite, etc., mainly used in petrochemical industrial gasification furnace. Carbon black reactor. Gasification furnaces. Ammonia decomposition furnaces. Second-stage conversion furnaces. High-temperature ultra-high-temperature furnaces for refractory ceramics industries. Blast furnaces for the metallurgical industry.
2. Modified high alumina bricks:
(1) Low creep high alumina bricks: For high alumina bricks with a creep temperature of 1500°C-1550°C, a low creep high alumina brick can be obtained by adding some fused alumina and silica raw materials.
(2) Phosphate bonded high-alumina brick: The main raw material is special grade or first-grade high alumina blanched clinker, phosphoric acid solution or aluminum phosphate solution is used as a binding agent, and a small amount of fused alumina, mullite, etc. are added to strengthen the matrix. 600 °C heat treatment made of chemically bonded refractory products. Mainly used in iron stoves, cement kiln, electric furnace roof, ladle and so on.
3. Corundum – mullite products: the use of fused white corundum. Tabular corundum. Fused mullite and other raw materials, the ingredients. Mixing. High pressure molding, high temperature kiln firing. The main crystalline phase of the product is corundum, and the bonded phase is mullite. Mainly used in the ceramic industry’s high-temperature firing kiln and push plate. Sets such as kiln furniture.
Various kinds of corundum raw materials can be used as aggregates and powders for the preparation of unshaped refractory products. According to different binders, construction methods can be divided into the following categories:
Refractory Castable: Corundum, Corundum-spinel, Corundum-SiC-C
Fire-resistant plastics: corundum, aggregates: all types of corundum; binders: water glass, phosphate, organic binders.
Refractory ramming material: corundum, aggregate: all kinds of corundum; binder: phosphoric acid, phosphate, etc.
Refractory mud: joints for corundum fireproof masonry.