High Performance Refractory Castable

The high-performance castables adopt the high-performance micro-powder and ultra-fine powder combination technology. It is an important component of the development of new technology refractory castables and an important branch in the new milestone of refractory castables. It has achieved good results in various industrial kilns.

The high-performance ultra-fine powder combined refractory castables are developed on the basis of high-tech refractory castables. The theoretical basis of its ingredients, the selection principles and varieties of materials, the concept of strengthening the matrix, the selection of critical particle size and its particle grading, and the design of the mix ratio are all the same. The difference between the two is that ultra-fine powder replaces aluminate cement, overcomes the defects of cement, and gives play to the advantages of ultra-fine powder. Therefore, the formulated ultra-fine powder combined refractory castables, in addition to maintaining the characteristics of refractory castables, also improves slag resistance, has a very small high and medium temperature strength ratio, and improves the high performance of heat spalling resistance.

 

The high-performance ultra-fine powder combined refractory castables are different from ordinary cement-free refractory castables. The former uses a small amount of SiO2 ultrafine powder and has the combined effect of magnesium materials, so the drying strength is high, and the medium and high temperature strength meets the use requirements; the latter uses a large amount of SiO2 ultrafine powder, but the drying strength is low. At medium and high temperatures, it is over-sintered and has a high strength, which is not conducive to use. Compared with the two, the former also has high performance.

In high-performance ultrafine powder bonded refractory castables, α-Al2O3 ultrafine powder is generally added. Its function is to increase the fluidity of the material at room temperature, improve the construction performance, react with active SiO2 at medium and high temperatures to form mullite, and react with MgO to form spinel, which are helpful for the strength and other properties of the castable.

The coagulation and hardening mechanism of ultrafine powder bonded refractory castables is: the coagulation bonding of μf-SiO2 is the main one, and the hydration bonding of MgO is the auxiliary one. Therefore, the ultrafine powder binder mainly refers to the active SiO2 ultrafine powder, and its general dosage is less than 3%. The binder still maintains the siloxane network structure at higher temperatures, and reacts with other minerals to form a high-temperature phase, which can strengthen the matrix, improve the strength and slag resistance, so as to meet the needs of thermal equipment such as high-temperature smelting.

The matrix materials of high-performance castables are super-grade bauxite, corundum powder, fused magnesia powder, high-purity alumina-magnesia spinel powder, Cr2О3 powder, α-Al2О3 and SiO2 ultrafine powder, aluminate ice mud CA-70 or CA-80 and admixtures. Select the material particle grading and scientifically combine the material formula. Its varieties include low-cement-bonded alumina-magnesia spinel, alumina-magnesia and alumina-spinel refractory castables, ultrafine powder-bonded alumina-magnesia spinel and magnesia refractory castables, chromium-containing refractory castables, etc.

The refractory aggregates of high-performance castables include plate-shaped corundum, dense corundum, white corundum, alumina-based corundum, super-grade alumina clinker, fused high-purity magnesia and alumina spinel, etc. In order to improve the thermal shock resistance, i.e. spalling resistance, of refractory castables, the critical particle size of refractory aggregates tends to increase, sometimes 30mm is selected, and 25mm is more commonly used. The particle size distribution (%) of refractory powder, i.e. matrix material, is: 0.074mm~5μm and <5μm, and the particle size distribution of refractory aggregate and refractory powder.

Suitable for petrochemical tubular furnaces, metallurgical steel rolling heating furnaces, industrial boilers and various heating furnace bottoms, furnace walls, flues, etc. in petrochemical, electric power, building materials, metallurgy and other industries. It can be made into various special-shaped prefabricated parts and can also be cast on site.

Note: Various grades of high-performance castables can also be produced according to user requirements.

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