Low Cement Refractory Castable Introduction. Cost-effective low-cement Castable with Excellent Thermal Shock Stability. Low cement castables are one of the most widely used castables in thermal kiln linings, with Cost-Effective performance and easy construction. Low-cement castables have the advantages of less water addition, high density, good volume stability, and high strength at high temperatures.

The 3 Different Low-Cement Refractory Castables

Low cement refractory castable mainly includes three types: Low Cement Aluminum Silicate Refractory Castable, Low Cement Mullite Corundum Castables, Low Cement SiC Refractory Castable, etc. The Low Cement series Castables are widely used as linings in reheating furnaces and other industrial furnaces.

(1) Low Cement Aluminum Silicate Refractory Castable

Low-cement aluminum silicate refractory castables use first-grade clay clinker and first-grade to special-grade alumina clinker as aggregates. Generally, the maximum particle size is 10mm and the dosage is 70%. Refractory powder is made of special grade or first-grade bauxite clinker powder or brown corundum powder, etc., and its dosage is 18% to 24%. Ultrafine powder uses α-Al2O3 powder and silica fume, the dosage is 6%~12%. Add an appropriate amount of compound water-reducing agent. High-Alumina Low Cement Castable.

Performance Advantages of Low Cement Aluminum Silicate Refractory Castables

The refractory degree of low cement refractory castable is greater than 1790℃. The load softening temperature under 0.2MPa (deformation 4%) is 20~100℃ higher than that of CA-50 cement refractory castable. Therefore, the service temperature of low-cement refractory castables is generally about 100°C higher than that of CA-50 cement refractory castables of the same material.

The high strength and medium-temperature strength of low-cement refractory castables do not decrease but increase significantly. There are many reasons for this.

Among them, the dehydration of calcium aluminate hydrate is carried out slowly and continuously within a large temperature range. And less damage to the crystal structure.

Low-cement refractory castables have less total pores, more small capillary pores and even distribution. That is, it has the characteristics of low pores, good pore structure, poor air permeability and strong resistance to slag erosion. This is also one of the reasons for the high strength of this castable.

Due to the low apparent porosity of low-cement refractory castables, the structure is dense. Therefore, it has high strength at medium and high temperatures.

Low cement refractory castables have high strength, good wear resistance, low apparent porosity and few low melting point materials. Therefore, it has strong resistance to slag invasion.

The thermal shock resistance of low cement refractory castables, that is, the number of cycles of water cooling after heating to 1100°C, is the same as that of CA-50 cement and clay combined refractory castables. are more than 15 times. Its thermal conductivity is slightly higher than that of CA-50 cement and clay combined refractory castables due to its low pores and dense structure. Its value is generally 1.05~1.35W/(m·K).

(2) Low Cement Mullite Corundum Castables

Low cement mullite corundum refractory castables use sintered or electric fused mullite, brown corundum, alumina-based corundum and white corundum as refractory bone powder. Sometimes special-grade alumina clinker powder is also used, and ultra-fine powder is mixed with α-AI2O3 and silica fume. It is formulated with aluminate cement as binder and additional dispersant. This material is used for steel rolling heating furnace lining, water cooling pipe wrapping and burner bricks, and tundish slag weir. On thermal equipment such as tap troughs and electric furnace covers of medium and small blast furnaces. The use effect is better. Low Cement Mullite Corundum Refractory Castable.

(3) Low Cement SiC Refractory Castable

Low cement SiC refractory castables are characterized by low linear expansion coefficient, high thermal conductivity, high strength and good wear resistance. It has been widely used in thermal equipment such as power generation boilers, non-ferrous metallurgical furnaces and incinerators. Low Cement Silicon Carbide Castable.

Low-cement SiC refractory castables use silicon carbide with SiC greater than 97% as refractory aggregate and powder. Add SiO2 ultrafine powder and metallic silicon antioxidant, use CA-70 cement as the binding agent and add polyphosphate water-reducing agent. The main properties of this material are 85% SiC and drying volume density at 110°C. The compressive and flexural strengths are 2.5g/cm3, 45MPa and 9MPa respectively. The wire change, pressure resistance and flexural strength after burning at 1000℃ are -0.2%, 107MPa and 24MPa respectively. The wire change, pressure resistance and flexural strength after burning at 1450℃ are +0.3%, 130MPa and 54MPa respectively. The thermal conductivity at 400℃ is 12.2W/(m·K).

Application of Low Cement Refractory Castables

1.  Furnaces of metallurgy industry, heat treatment furnace.
2.  Furnace of incineration of garbage, recirculating fluidized bed furnace.
3.  Furnaces of the chemical industry and construction industry.
4.  Tundish lining.

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