Low cement refractory castables refer to low cement refractory castables of aluminum silicate, magnesium and silicon, among which the earliest development, the deepest basic research work and the most application are aluminum silicate low cement refractory castables.
1. Low cement aluminum silicate refractory castable
Low cement aluminum silicate refractory casting material is made of first-class clay clinker and first-class ~ special grade alumina clinker as aggregate, generally the largest grain
Diameter is 10mm and dosage is 70%; Refractory powder with special or first grade alum clinker powder or brown corundum powder, etc., the dosage is 18%
～24%; Use α-Al2O3 powder and silica ash for ultra-fine powder, and the dosage is 6% to 12%. With the increase of heating temperature, the strength of the castable material increases significantly, and the strength of 1500 °C is about 1 times higher than the drying strength. 1400 °C high temperature flexural strength of 1.5 ~ 2.3MPa, nearly double the CA-50 cement refractory castables; 1400 °C or 1500 °C after-firing line changes, generally in an expanded state, its absolute value is smaller, but relatively stable, that is, the volume change is relatively small, conducive to the use of castables; CaO content meets the requirements of low cement refractory castables.
2. Low cement magnesium silicate refractory castable
Low cement magnesium refractory casting material is divided into mullite and corundum castable, low cement mullite and corundum refractory casting material is the use of sintered or electrofusion mullite, brown corundum, bauxite-based corundum and white corundum as refractory bone powder, sometimes also with special grade bauxite clinker powder, ultra-micro powder is mixed with a-Al2O3 and silica ash, with aluminate cement as a binding agent and additional dispersant formulation. The material is used in rolling steel heating furnace lining, water cooling pipe bandaging and burner bricks, middle bag slag weir, medium and small blast furnace iron ditch and electric furnace cover and other thermal equipment, the use effect is better.
3. Low cement silicate silicon refractory castable
Low cement SiC refractory castable is characterized by low linear expansion coefficient, high thermal conductivity, high strength, good wear resistance, in the power generation boiler, non-ferrous metallurgical furnace and incinerator and other thermal equipment, has been applied, the use of good effect.
Low cement SiC refractory casting material uses SiC greater than 97% silicon carbide as refractory aggregate and powder, Add SiO2 ultra-fine powder and silicon metal antioxidant, ca-70 cement as a binder and add polyphosphate superplasticizer. The main properties of the material are SiC of 85%, 110 °C drying bulk density, pressure resistance and flexural strength of 2.5g/cm, 45 MPa and back to 9 MPa and 1000 °C after firing line change, pressure resistance and flexural strength are -0.2%, 107 MPa and 24 MPa, 1450 °C post-firing line change, pressure resistance and flexural strength are +0.3%, 130 MPa and 54 MPa, respectively, and 400 °C thermal conductivity is 12.2 W/(m·K).
Low cement castable features:
In the low cement refractory castable, the amount of water is small, the volume density is large, the porosity is small, the microstructure is dense, so the strength is high, the wear resistance is good, the pressure strength at room temperature (3d) is 12~40MPa, and the drying compressive strength is 30~100MPa. With the increase of the heating temperature, the compressive strength after burning increases significantly, and the strength of the Chinese does not decrease. In the range of 800 ~ 1500 °C, its strength is increased by 50 ~ 70 MPa compared with CA-50 cement refractory castable, which is very beneficial to use at high temperatures.
Applications for low cement castable products:
Low cement castables are mainly used in metallurgy, electric power, nonferrous metals, petrochemicals, building materials and other industries. Such as glass kiln trough bottom, cement kiln front and rear kiln door cover cooler front and other high temperature-resistant parts, front and rear kiln mouth, coal injection pipe, etc.; heating furnace, equal heat furnace and other heat treatment furnaces; medium frequency induction furnace lining, petrochemical catalytic cracking reactor high temperature wear-resistant lining, other industrial furnace lining.