Alumina Bubble Brick

what is alumina bubble brick?

Alumina bubble brick is a high temperature refractory material, mainly composed of alumina (Al₂O₃), with extremely high fire resistance and thermal shock resistance. This brick is made by introducing bubbles or foams into bauxite or alumina powder and then sintering at high temperature. The presence of bubbles makes the material have good insulation properties, reduces heat conduction, and is suitable for lining and insulation layers of high temperature furnaces.

Other popular insulation bricks

• Fire Clay Insulating Brick
• High Alumina Insulating Brick
• Mullite Insulating Brick

alumina bubble brick price

Physical and chemical indicators of alumina bubble bricks

index	Numeric
Chemical composition
Al₂O₃	≥90%
SiO₂	≤10%
Fe₂O₃	≤1.5%
Na₂O + K₂O	≤0.5%
Bulk density (g/cm³)	0.8-1.2
Apparent porosity (%)	60-75%
Normal temperature compressive strength (MPa)	≥3.0
Load softening point (℃)	≥1600
Re-firing line changes (1500℃×3h)	±0.5%
Thermal conductivity (W/m·K, 350℃)	0.25-0.30
Operating temperature (℃)	Up to 1800
Thermal shock resistance (1100℃ water cooling, times)	≥20

Advantages of alumina bubble bricks

1. Excellent high temperature performance: Alumina bubble bricks have high refractoriness, usually above 1800℃, and can withstand high temperature environments without softening or deformation.
2. Excellent thermal stability: It has good thermal shock resistance, can maintain structural stability when changing rapidly between high and low temperatures, and is not easy to crack.
3. Low thermal conductivity: The thermal conductivity of bubble alumina bricks is low, about 0.25-0.30 W/m·K (at 350℃), which helps to reduce heat loss and improve energy efficiency.
4. Lightweight: Due to the existence of bubble structure, the volume density of bubble alumina bricks is low (about 0.8-1.2 g/cm³), which makes it reduce the weight of the structure while ensuring strength.
5. High strength: Despite the low density, its compressive strength at room temperature is still high, generally above 3.0 MPa, suitable for bearing certain mechanical pressure.
6. Chemical erosion resistance: Alumina bubble bricks have good chemical stability and are not easily corroded by chemicals such as acids and alkalis. They are suitable for high temperature corrosion environments in industries such as chemical and metallurgy.

alumina bubble brick bulk price

How are alumina bubble bricks produced?

Raw material preparation:

• The main raw material is high-purity alumina powder (Al₂O₃), and the Al₂O₃ content is usually required to be above 90%.
• Auxiliary materials may include binders, fluxes, stabilizers, etc., such as silicon oxide (SiO₂), iron oxide (Fe₂O₃), etc.

Mixing and granulation:

• Mix the alumina powder and other additives in proportion, usually using a ball mill or mixer for uniform mixing.
• The mixed material is formed into tiny particles through spray drying or granulation process, which are convenient for subsequent molding and sintering.

Molding:

• The formed particles are made into a green body of a certain shape by pressing or extrusion molding. During molding, an appropriate amount of water or other binders can be added to improve the strength and plasticity of the green body.

Drying:

• The green body after molding needs to be dried to remove the moisture in it and prevent bubbles or cracks from forming during the sintering process. The drying process is usually carried out in a low temperature environment.

Sintering:

• The dried green body enters the high-temperature sintering furnace for sintering. The sintering temperature is usually above 1600℃, and the specific temperature and time depend on the desired final properties.
• During the sintering process, the alumina particles are combined by diffusion to form a dense alumina structure, while the bubbles are retained to form a porous structure.

Bubble generation:

• During the sintering process, the formation and stability of bubbles can be promoted by controlling the temperature, time and atmosphere. These bubbles are generated by chemical reactions or physical processes inside the material.

Cooling and inspection:

• After sintering, the brick body needs to be cooled slowly to prevent cracks caused by rapid temperature changes.
• After cooling, quality inspection is carried out, including testing of indicators such as bulk density, strength, and porosity to ensure that the product meets the standards.

Cutting and processing:

• As needed, the sintered alumina bubble bricks can be cut, polished, and processed to achieve specific sizes and shapes.

Packaging and storage:

• Qualified products are packaged to prevent damage during transportation and storage.

Alumina bubble brick application scenarios

Glass melting furnace; ceramic kiln; metallurgical furnace; chemical reactor; incinerator; boiler; heat exchanger; thermal protection system; cracking furnace; high temperature insulation layer; fire protection, welcome to consult Henan Lit Refractory Materials.

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