Alumina hollow ball castable is a lightweight refractory material made of alumina hollow balls as the main aggregate, combined with high-purity alumina powder, silica powder and appropriate binder (such as aluminate cement or phosphate) in a scientific ratio. Its core component, alumina hollow balls, are prepared by high-temperature melt blowing or spray granulation. They have a closed-cell structure, with a particle size of usually 0.2-5mm and a porosity of up to 50%-70%, giving the material a significant lightweight property. The volume density is only 1.0-1.8g/cm³, which is 30%-50% lighter than traditional refractory materials.
Performance of alumina hollow ball castables:
Alumina hollow ball castable have both high strength and excellent thermal insulation performance, with a compressive strength of 5-30MPa at room temperature, stable structure at high temperature, load softening temperature exceeding 1600℃, and maximum operating temperature up to 1800℃. The unique hollow ball structure effectively blocks heat conduction, with a thermal conductivity as low as 0.3-0.8W/(m·K), which is more than 50% lower than that of dense castables, significantly reducing heat energy loss. At the same time, the buffer network formed by closed pores gives excellent thermal shock resistance, and can withstand more than 100 (1100℃⇄water cooling) rapid cooling and heating cycles without cracking.
Production process of hollow alumina ball castables:
Dry vibration casting or wet casting is used to form the material. By optimizing the particle grading and bonding system, the construction fluidity and structural density after sintering are ensured. After curing, the material is sintered at a high temperature of 1350-1550℃ to form a three-dimensional network structure dominated by corundum phase, achieving a balance between mechanical and thermal properties.
Application of hollow alumina ball castables:
In industrial applications, this material is widely used in ladle covers and heating furnace tops in the metallurgical industry, cracking furnace linings in the petrochemical industry, shuttle kiln linings in the ceramic industry, and high-temperature testing equipment for aerospace. Its lightweight characteristics reduce the load on the kiln steel structure, low thermal conductivity improves energy efficiency, and convenient construction shortens the construction period. For example, a steel company used this material to transform the heating furnace, reducing energy consumption by 15%, extending the service life to 3 years, and saving more than one million yuan in annual maintenance costs.
As a representative of green refractory materials, alumina hollow ball castables help high-energy-consuming industries achieve carbon neutrality goals by reducing heat storage and improving thermal efficiency. It has become the preferred lining material for upgrading high-temperature industrial equipment.