An alumina bubble brick is a lightweight refractory insulation brick made primarily from hollow alumina spheres with Al₂O₃ content typically ranging from 90% to 99%.
By combining advanced forming technology with high-temperature sintering, this brick offers an exceptional balance of ultra-high temperature resistance, low thermal conductivity, low bulk density, and stable structural strength.
(1) Ultra-lightweight structure with high alumina purity
(2) Excellent high-temperature insulation performance
(3) High service temperature capability
(4) Low heat storage and fast thermal response
(5) Good dimensional stability at high temperatures
(6) Adequate mechanical strength for insulation linings
(1) High-temperature industrial furnaces:Electric furnace, heat treatment furnace, laboratory furnace, shuttle kiln, batch kiln, annealing furnace, sintering furnace.
(2) Ceramic and advanced materials industry:High-temperature ceramic kilns, technical ceramic firing furnaces, catalyst calcination furnaces, powder sintering furnaces.
(3) Nonferrous metal and special metallurgy:Aluminum holding furnace insulation layer, copper and nickel heat treatment furnaces, nonferrous alloy melting furnace insulation zones.
(4) Energy-saving and special thermal equipment: High-temperature insulation lining of reformer furnaces, cracking furnaces, waste incinerators, high-temperature reactors and thermal processing units
Below are representative technical specifications. Custom grades are available upon request.
| Property | Typical Value | Practical Meaning |
| Al₂O₃ Content | 90–99% | Higher purity ensures higher service temperature |
| Bulk Density | 1.3–1.9 g/cm³ | Lightweight structure reduces furnace load |
| Apparent Porosity | ≥70% | Improves insulation efficiency |
| Cold Crushing Strength | 6–18 MPa | Sufficient strength for furnace construction |
| Thermal Conductivity (1000°C) | 0.9–1.2 W/m·K | Lower heat loss, better energy saving |
| Refractoriness | ≥1800°C | Suitable for ultra-high temperature zones |
| Permanent Linear Change | ≤0.5% | Stable dimensions during long-term use |
Note: Exact parameters can be adjusted according to application requirements.
Alumina Bubble Brick is a premium lightweight insulation refractory brick manufactured from high-purity alumina hollow spheres (alumina bubbles) as the main aggregate. By combining advanced forming technology with high-temperature sintering, this brick offers an exceptional balance of ultra-high temperature resistance, low thermal conductivity, low bulk density, and stable structural strength.
Compared with traditional insulating fire bricks or lightweight high alumina bricks, alumina bubble bricks provide superior thermal insulation performance at extremely high temperatures, making them an ideal solution for energy-saving furnace linings where heat retention, reduced heat loss, and lightweight structure are critical.
Alumina bubble bricks are widely used as hot-face or backup insulation linings in industrial furnaces operating under high temperatures, especially in applications where conventional insulation materials cannot meet temperature or purity requirements.
An alumina bubble brick is a lightweight refractory insulation brick made primarily from hollow alumina spheres with Al₂O₃ content typically ranging from 90% to 99%.
These hollow spheres create a unique closed-pore structure inside the brick, which provides:
Excellent thermal insulation
Extremely low heat storage
Reduced furnace weight
High refractoriness and chemical stability
Unlike clay-based or low-alumina insulation bricks, alumina bubble bricks maintain stable performance even at temperatures above 1700°C, making them suitable for high-end industrial furnace applications.
With high-purity alumina as the main component, alumina bubble bricks exhibit excellent refractoriness and thermal stability.
Typical service temperature: up to 1800°C
Minimal shrinkage under high-temperature conditions
Maintains insulation performance during long-term operation
This makes alumina bubble bricks suitable for furnaces with extreme thermal environments where ordinary insulation bricks fail.
The closed hollow structure of alumina bubbles significantly reduces heat transfer.
Low thermal conductivity
Reduced heat loss through furnace linings
Improved thermal efficiency
Lower fuel or energy consumption
As a result, alumina bubble bricks are often selected for energy-saving furnace designs, especially where long-term operating cost reduction is a priority.
Compared with dense refractory bricks, alumina bubble bricks have a much lower bulk density.
Reduced furnace structural load
Faster heating and cooling cycles
Lower heat storage loss during intermittent operation
This is particularly beneficial for batch furnaces, shuttle kilns, laboratory furnaces, and heat treatment furnaces that require frequent start-stop operation.
Although lightweight, alumina bubble bricks still provide sufficient cold crushing strength for normal furnace construction and maintenance.
Easy handling and installation
Stable structure during service
Suitable for both hot-face insulation and backup layers
This balance between strength and insulation is a major reason why alumina bubble bricks are preferred in high-performance furnace linings.
Thanks to the high alumina content, alumina bubble bricks show strong resistance to:
Oxidizing and neutral atmospheres
Chemical corrosion from most industrial gases
Thermal shock under controlled heating schedules
They are especially suitable for clean, high-temperature environments where contamination must be minimized.
The performance of alumina bubble bricks depends heavily on precise manufacturing control. At Highland Refractory, the production process includes:
Raw Material Selection
High-purity alumina hollow spheres are carefully selected to ensure consistent size, strength, and purity.
Batching & Mixing
Alumina bubbles are uniformly mixed with selected bonding materials to maintain pore structure integrity.
High-Pressure Forming
Advanced pressing techniques ensure uniform density and accurate dimensions.
Controlled Drying
Proper drying prevents cracking and maintains internal pore structure.
High-Temperature Sintering
Fired at carefully controlled temperatures to achieve optimal strength and stability.
Precision Machining & Inspection
Dimensional accuracy and physical properties are strictly inspected.
Secure Packaging
Export-standard packaging ensures safe transportation.
This strict process control ensures consistent quality, reliable performance, and long service life.
Proper installation is essential to maximize the performance of alumina bubble bricks.
Use appropriate refractory mortar compatible with high-alumina materials
Ensure uniform brick joints to prevent heat bridges
Avoid excessive mechanical stress during installation
Follow controlled heating-up schedules during initial furnace startup
Can be used as hot-face insulation in high-temperature zones
Often combined with dense refractory bricks or castables
Suitable as backup insulation behind working linings
Our technical team can provide installation guidance and lining design suggestions based on your furnace type.
Alumina bubble bricks are widely used across various industries:
High-temperature heat treatment furnaces
Electric furnaces
Laboratory and experimental furnaces
Shuttle kilns and batch kilns
Ceramic Industry: Kiln insulation and hot-face linings
Petrochemical Industry: Reformers and cracking furnaces
Power Industry: High-temperature insulation zones
Non-Ferrous Metallurgy: Aluminum and copper furnaces
Environmental Engineering: Waste incinerators and biomass furnaces
Their lightweight and insulation advantages make them especially suitable for energy-saving retrofits.
| Type | Max Service Temp | Insulation Performance | Strength | Typical Use |
| Alumina Bubble Brick | Up to 1800°C | Excellent | Moderate | Ultra-high temp insulation |
| High Alumina Insulation Brick | ~1700°C | Good | Higher | High-load insulation |
| Lightweight Fire Clay Brick | ~1200°C | Moderate | Lower | Backup insulation |
Alumina bubble bricks are the preferred choice when both insulation efficiency and ultra-high temperature resistance are required.
We offer:
Custom sizes and shapes
Different alumina purity grades
Tailored solutions based on furnace design
Stable bulk supply for large projects
With decades of refractory manufacturing experience, Highland Refractory provides reliable delivery and technical support for international customers.
Over 30 years of refractory manufacturing experience
Advanced production lines and strict quality control
Competitive pricing with global standards
Technical support from application engineers
Trusted supplier for customers worldwide
If you are looking for a high-performance insulation refractory for high-temperature furnaces, our Alumina Bubble Brick is a proven solution.
📩 Contact us today to request a quote, datasheet, or application recommendation.
Our technical team is ready to support your project from design to installation.
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