The defining characteristics of refractory fire bricks include:
1. High temperature resistance
2. Good wear resistance
3. Weakly acidic at high temperatures
4. Strong erosion resistance
5. Good volume stability
6. Low prices
Used for lining blast furnaces, hot blast furnaces, electric furnace roofs, oxygen converters, reverberatory furnaces, and rotary kilns. They are also widely used as regenerative flat furnace checker bricks, plugs for pouring systems, and water mouth bricks, among other applications.
|
Item |
Index |
||||||||
|
Model |
N-1 |
N-2a |
N-2b |
N-3a |
N-3b |
N-4 |
N-5 |
N-6 |
|
|
Refractory temperature（℃≥） |
1750 |
1730 |
1730 |
1710 |
1710 |
1690 |
1670 |
1580 |
|
|
Bulk densityg/cm3 |
2.1 |
-- |
-- |
-- |
-- |
2.0 |
-- |
2.0 |
|
|
Softening temperature under load[0.2MPa*0.6%]≥ |
1400 |
1350 |
-- |
1320 |
-- |
1300 |
-- |
-- |
|
|
Reburning line change rate（%） |
1400℃*2h |
+0.1-0.4 |
+0.1-0.5 |
+0.1-0.5 |
-- |
-- |
-- |
-- |
-- |
|
1400℃*2h |
-- |
-- |
-- |
+0.2-0.5 |
+0.2-0.5 |
+0.2-0.5 |
+0.2-0.5 |
-- |
|
|
Apparent porosity（%≤） |
22 |
26 |
24 |
24 |
26 |
24 |
26 |
28 |
|
|
Normal temperature compressive strength（MPa≥） |
30.0 |
20.0 |
25.0 |
20.0 |
15.0 |
20.0 |
15.0 |
15.0 |
|
Refractory fire bricks are essential materials in high-temperature industrial environments, playing a critical role in protecting furnace structures, maintaining thermal efficiency, and ensuring long-term operational stability. Widely used across industries such as iron and steel, cement, glass, ceramics, power generation, and petrochemical processing, refractory fire bricks are specifically engineered to withstand extreme heat, mechanical stress, and chemical attack.
Unlike ordinary construction bricks, refractory fire bricks are designed for continuous exposure to high temperatures, often exceeding 1,200°C, while maintaining structural integrity and consistent performance. Selecting the right refractory fire brick is not simply a matter of choosing the highest temperature rating—it requires a thorough understanding of material composition, furnace design, operating conditions, and service life expectations.
Refractory fire bricks are shaped refractory materials manufactured primarily from alumino-silicate raw materials such as fire clay, bauxite, and other mineral additives. They are designed to retain mechanical strength and dimensional stability under prolonged exposure to high temperatures, thermal cycling, and chemically aggressive environments.
The defining characteristics of refractory fire bricks include:
In industrial furnaces, refractory fire bricks serve as working linings, safety linings, or backup linings, depending on temperature zones and design requirements. Their performance directly affects furnace efficiency, maintenance frequency, and overall operating costs.
Refractory fire bricks are not a single product category. They are classified based on chemical composition, alumina content, density, and intended application. Understanding these differences is essential for proper selection.
Fire clay bricks are among the most widely used refractory fire bricks, typically containing 30–45% Al₂O₃. They offer a balanced combination of refractoriness, mechanical strength, and cost efficiency. Fire clay bricks are commonly used in medium-temperature zones, furnace walls, roofs, and backup linings where extreme chemical attack is limited.
They are valued for:
High alumina bricks contain higher alumina content, generally above 48% Al₂O₃, with some grades exceeding 70%. These bricks offer superior refractoriness, higher load-bearing capacity, and improved resistance to slag penetration.
They are typically selected for:
While high alumina bricks provide enhanced performance, they are heavier and more expensive, making them less economical for lower-temperature or backup applications.
Insulating fire bricks are lightweight refractory fire bricks characterized by high porosity and low thermal conductivity. Their primary function is insulation rather than mechanical strength.
They are used in:
Due to their lower strength, insulating fire bricks are not suitable for direct contact with molten materials or high mechanical stress.
Depending on furnace conditions, additional refractory fire bricks may be used, such as silica bricks, magnesia bricks, or chrome-containing bricks. These are selected for specific chemical environments or extremely high-temperature zones, but they are typically applied selectively rather than as general-purpose solutions.
When evaluating refractory fire bricks, technical datasheets often list numerous properties. However, only a few of these parameters directly determine real-world furnace performance.
Refractoriness under load indicates the brick’s ability to retain shape and strength while supporting weight at high temperatures. This is more relevant than maximum firing temperature, especially in furnaces with thick linings or structural loads.
Porosity affects both thermal insulation and chemical resistance. Lower porosity generally improves slag resistance and strength, while higher porosity reduces thermal conductivity. Bulk density reflects material compactness and is closely related to durability.
Furnaces rarely operate at constant temperatures. Rapid heating and cooling cycles can cause cracking or spalling. Refractory fire bricks must tolerate repeated thermal stress without structural failure, especially in batch furnaces or intermittent operations.
This property measures the brick’s ability to withstand mechanical load at room temperature. Higher crushing strength is essential for areas subject to impact, abrasion, or heavy lining loads.
Thermal conductivity determines how much heat is transferred through the lining. Dense refractory fire bricks offer mechanical protection, while insulating layers behind them help reduce heat loss and improve energy efficiency.
Refractory fire bricks are used across a wide range of industries, each with specific thermal and mechanical demands.
In steelmaking, refractory fire bricks are used in:
Their role is to provide structural stability, thermal containment, and resistance to wear in demanding operating environments.
Cement kilns and preheater systems rely on refractory fire bricks in:
These areas experience high temperatures combined with dust abrasion and chemical exposure, making balanced refractory performance essential.
In power plants and waste incineration facilities, refractory fire bricks line:
Here, thermal shock resistance and durability under fluctuating loads are particularly important.
Refractory fire bricks are used in:
Dimensional stability and consistent thermal behavior are critical to maintaining product quality.
Selecting refractory fire bricks requires matching material properties to actual service conditions, not just nominal temperature ratings.
Key selection considerations include:
In many designs, refractory fire bricks are combined with insulating bricks or castables to optimize both mechanical protection and thermal efficiency. Choosing an over-specified brick increases cost, while under-specification leads to premature failure.
Proper installation is as important as material selection. Refractory fire bricks are typically used in:
Design considerations include expansion joints, brick orientation, mortar selection, and compatibility with adjacent refractory materials. Incorrect installation often results in cracking, spalling, or uneven wear, reducing service life.
The service life of refractory fire bricks varies widely depending on operating conditions. Under normal industrial conditions, service life can range from several years to over a decade.
Factors that shorten service life include:
Correct selection, proper lining design, and regular inspection significantly extend refractory performance and reduce downtime.
High-quality refractory fire bricks require strict control throughout the manufacturing process:
At Highland Refractory, quality control focuses on consistency between batches, ensuring predictable performance during installation and operation.
For industrial projects, reliable delivery is essential. Refractory fire bricks are typically supplied in:
Highland Refractory has extensive experience supplying refractory fire bricks to international markets, supporting large-scale industrial furnace projects with stable lead times and technical documentation.
How hot can refractory fire bricks withstand?
Depending on grade, refractory fire bricks typically operate reliably between 1,200°C and 1,700°C.
How long do refractory fire bricks last?
Service life depends on application, but properly selected bricks often last 2–5years or more.
Are refractory fire bricks suitable for backup linings?
Yes, they are commonly used as backup linings behind higher-grade working linings.
Can refractory fire bricks be customized?
Custom sizes and shapes are widely available to fit specific furnace designs.
Refractory fire bricks remain a fundamental component of industrial furnace design, offering a reliable balance of heat resistance, mechanical strength, and cost efficiency. Their successful application depends on proper selection, thoughtful lining design, and correct installation.
With decades of manufacturing experience, Highland Refractory supplies refractory fire bricks engineered for consistent performance in demanding industrial environments. By combining material expertise with practical project support, Highland Refractory helps customers achieve longer furnace life, improved efficiency, and reduced maintenance costs.
Silicon carbide plates are mainly composed of silicon carbide (SiC) as the aggregate (with a content usually ≥ 80%).
