Low cement, ultra low cement high alumina refractory castable

Low cement cast-able refers to a new type of castable with a small amount of binder. The key point of electric furnace spray feeding is to use ultrafine particles of no more than 1 μm. Its thermal shock resistance, slag resistance and erosion resistance are significantly improved, surpassing similar refractory bricks. Further reduction of the binder content can produce ultra-low cement castables and cement-free castables.

Low cement, ultra low cement high alumina refractory castables refer to castables with lower cement content. The amount of cement used for refractory cement castables is generally 15% to 20%, and the amount of cement for low cement castables is about 5%, and some even decrease to 1% to 2%. The purpose of reducing the amount of cement is to improve the fire resistance of the castable.

It relies on the addition of several special raw materials to obtain good performance: pure calcium aluminate cement, because of the high content of effective mineral CaO·Al2O3, the lesser the incorporation, the desired strength can be obtained. The second silica fume is a glass microsphere having an SiO2 content of between 93% and 98% and an average particle diameter of about 0.5 μm. After the addition of silica fume, the flowability of the castable is good, the water requirement for molding is low, the sintering temperature is low, and the performance after heat treatment is avoided. Third, alumina fine powder, which is relatively easy to participate in the reaction and improve the fire resistance of the material. Fourth, the water reducing agent, which can adsorb on the surface of the powder, thereby generating electrostatic repulsion to disperse the powder, thereby further exerting the function of the fine powder.

Low-cement, ultra-low cement and high-aluminum refractory castables are high-tech refractories developed on common castables using rheological principles, tightest packing theory and ultrafine powder technology. It has the characteristics of low porosity, small pore size, high density, good volume stability, high strength and small water addition, and overcomes the characteristic that the strength of ordinary castables drops significantly at 800-1200 °C, and increases with temperature. When it is raised, the thermal shock resistance of the furnace body can be more than doubled.