What is the thermal conductivity of mullite insulation brick?

In industrial furnaces, heat-treatment equipment, and high-temperature energy-saving systems, one of the core performance indicators of insulation materials is thermal conductivity. The lower the thermal conductivity, the slower the transfer of heat through the material, resulting in better insulation, improved furnace efficiency, and reduced energy consumption.
So, what is the thermal conductivity of a mullite insulation brick?

Typical thermal conductivity range of mullite insulation brick

Because material density, raw-material purity, and manufacturing processes vary between brands, the thermal conductivity of mullite insulation brick also differs. Under 800°C, the industry reference range is:
Mullite insulation brick: 0.20–0.24 W/m·K

Generally, insulation bricks with thermal conductivity below 0.23 W/m·K at 800°C are already considered high-performance, capable of significantly reducing heat loss and improving thermal efficiency.

Why does CCEFIRE® mullite insulation brick achieve even lower thermal conductivity?

CCEFIRE® mullite insulation brick can consistently reach ≤ 0.17 W/m·K at 800°C, thanks to several key technological advantages:

Low-impurity, high-purity raw-material system
Using high-purity minerals from our own mines, the levels of Fe₂O₃and other low-melting impurities are strictly controlled. This ensures more complete mullite development, a stronger pore-wall structure, and reduced heat-transfer pathways.

Precisely controlled microporous structure
Unlike conventional insulation bricks with large and uneven pores, CCEFIRE® develops a uniform and closed microporous structure through formulation and optimized forming technology:
Gas convection is minimized, lower thermal conductivity
Strong pore walls, no coarse pores or pore connection during long-term operation

88-meter fully automated tunnel kiln firing
With consistent and accurate heat-field control, mullite crystallization becomes more complete and the internal structure more compact, avoiding loose pores caused by underfiring and shrinkage collapse caused by overfiring. As a result, thermal-conductivity stability is fundamentally improved.

What real-world benefits does lower thermal conductivity bring?

Lower thermal conductivity is more than a numerical advantage — it directly translates into measurable industrial performance:
Lower furnace shell temperature
Reduced fuel consumption
Faster heating and higher thermal efficiency
Longer maintenance intervals and fewer shutdowns
For furnaces operating continuously at 1100–1400°C, every 0.01 W/m·K difference in thermal conductivity becomes magnified over thousands of hours, ultimately affecting total energy consumption and service life.

The answer is not just a numerical range — it is a key factor that determines furnace operating cost, thermal efficiency, and durability.
With high-purity raw materials, a uniform microporous structure, and stable firing technology, CCEFIRE® mullite insulation brick consistently maintains a lower and more durable thermal-conductivity performance, enabling safer, more energy-efficient, and more economical operation across high-temperature systems.