Aluminum carbon brick related knowledge, classification and use
Aluminum carbon brick refractories containing Al2O3 and C as main components, containing Al2O3 35%~85% and containing C 7%-35%. Can be divided into two categories of burnt bricks and non-burned bricks.
Aluminum carbon bricks have high refractoriness, good chemical stability and corrosion resistance. If ZrO2 is added to the ingredients, good thermal shock resistance can be obtained. The sintered aluminum carbon bricks containing 72%~85% of Al2O3 and 7%~8% of C can reach 110~120MPa, the bending strength of 1400°C is 25MPa, and the content of Al2O3 is 35%~46%, C+SiC 30 The compressive strength of %~37% of fired aluminum carbon bricks is 21~28MPa.
Aluminum carbon bricks are mainly used as sliding nozzle slides, continuous casting tundish integral plugs, etc., and can also be used as lining for hot metal pretreatment and lining of steel drums.
This series of products, such as bauxite clinker, corundum and graphite, are the main materials and are used in various differential additives. They have good microporous index, excellent alkali resistance and high thermal conductivity. Applicable to different furnaces and high aluminum furnace waist, furnace belly, cooling wall aluminum brick and other parts.
A carbon-containing refractory product made of corundum (or high alumina bauxite, mullite) and graphite. Aluminum carbon bricks can be divided into fired aluminum carbon bricks and non-fired aluminum carbon bricks according to different manufacturing processes.
From the search for refractory materials, the main points of the process of manufacturing aluminum carbon bricks are: adding carbon raw materials to the main raw materials of alumina, adding small amounts of other raw materials such as silicon powder, SiC powder, aluminum powder, etc., using phenolic resin or asphalt The binder is fired in a reducing atmosphere by compounding, mixing, isostatic pressing (or machine forming).
The main points of the process of manufacturing non-burned aluminum carbon bricks are the same as not burning bricks.
The fired aluminum carbon brick belongs to a ceramic bond or a ceramic-carbon composite bond material, and is widely used as a sliding nozzle slide, a long nozzle, an immersion nozzle, a drain brick and an integral stopper rod for continuous casting. Non-burning aluminum carbon bricks are carbon-bonded materials. Because of their superior oxidation resistance to magnesia-carbon bricks and excellent corrosion resistance to Na2O-based slags, they have been widely used in hot metal pretreatment equipment.
Application of phenolic resin in aluminum carbon brick
Aluminium carbon brick is made by using corundum and graphite as raw materials and adding a certain amount of binder and additive. Since Al2O3 and C do not undergo a solid phase reaction at the firing temperature of the product, the bonding strength of the aluminum carbon brick is mainly derived from the binder and the additive. Phenolic resins are widely used in aluminum carbon bricks due to their excellent properties. However, there are some disadvantages when the phenolic resin is used as a binder for aluminum carbon bricks. The main manifestation is that at 300 ° C to the medium temperature region where metal is bonded to aluminum, the strength of the material is lowered due to the decomposition of the phenolic resin binder, resulting in the material being When used in the medium temperature region, it is easy to cause damage such as oxidation and "face shortage". In order to overcome these shortcomings, many researchers have conducted in-depth research on phenolic resin for aluminum carbon bricks.
Han Bing et al. used the principle of in-situ intercalation polymerization to introduce nano-clay into phenolic resin to synthesize modified phenolic resin, and studied the effect of the modified resin on the performance of aluminum carbon brick. It was found that in the process of polymerization of phenol and formaldehyde, the clay was polymerized into the phenolic resin by in-situ intercalation to form a phenolic resin-clay intercalation composite, which can effectively improve the normal temperature compressive strength and high temperature resistance of the aluminum carbon brick. Fold strength.
Qiangmin et al. introduced transition metal molybdenum into phenolic resin to synthesize molybdenum modified phenolic resin. The structure and thermal properties of molybdenum modified phenolic resin and the medium temperature strength of aluminum carbon bricks combined with it were studied. It was found that molybdenum is bonded to the resin molecular chain in the form of a chemical bond, which can increase the pyrolysis temperature of the phenolic resin; the compressive strength of the aluminum carbon brick sample prepared by using it as a binder at 200, 500 and 600 ° C The samples combined with the ordinary resin were increased by 23.1%, 51.2% and 70.3%, respectively.
In addition, the method of doping a phenolic resin with a transition metal compound described in the literature is also applied to the study of aluminum carbon bricks. Luo Ming et al. modified NiNO3·6H2O into phenolic resin and found that the degree of graphitization of the modified phenolic resin after treatment at 1 050 °C is much higher than that of ordinary resin. The density and mechanical properties of the modified resin-bonded aluminum carbon bricks were significantly better than those of the common resin. The SEM analysis showed that the modified resin-bonded samples produced carbon nanotubes after treatment at 1 400 °C.
In addition to its wide application in the preparation of magnesia carbon and aluminum carbon bricks, phenolic resins can also be used as binders for carbon-containing shaped products such as MgO-SiC-C and Al2O3-SiC-C.