Refractoriness of Insulation Bricks

Insulation brick is a type of insulation material. It can reduce heat loss, save energy, reduce the weight of the furnace and reduce the total cost of the furnace. 

The pores in insulation bricks are generated by adding lightweight aggregates such as combustible materials, blowing agent and hollow balls. Those pores have big size, good insulation performance and mechanical properties. If increasing the volume fraction, many large pores will gather together and affect the insulation performance. However, insulation bricks have small specific surface area and low specific surface energy. Therefore, it has good thermal stability and low potential of deterioration. 

 

The main properties of insulation brick include bulk density, porosity, thermal conductivity, service temperature and mechanical strength. Just a few insulation materials can fully meet the requirements.  

 

According to the service temperature, it can be divided into low-temperature type (<900℃, diatomite brick), medium-temperature type (1000℃, fire clay insulation brick) and high-temperature type (>1200℃, high alumina insulating brick)

 

According to bulk density, it can be classified into sub-light weight brick (1.00-1.39 g/cm3), light weight brick (0.4-1.0 g/cm3) and ultra-light weight brick (<0.49 g/cm3). 

 

According to the shape, it can be divided into fibrous materials, porous materials and granular materials. 

 

The service temperature and features of the insulation bricks are as followings.

	Service temperature/℃	Features
Diatomite Insulation Brick	<900	made from natural porous materials; low thermal conductivity; good insulation performance;
Fire clay insulation brick	900-1100	Mainly made by adding combustible substances; has a wide application;
High alumina insulating brick	1100-1250	can contact flame directly; has a wide application;
Cordierite brick	1300	Has low thermal expansion and spalling résistance;
Corundum insulation brick	≥1600	Has a high content of Al2O3; mainly composed of α-Al2O3; can be used in a reducing atmosphere;
Silica insulation brick	1220-1550	High softening temperature under load,; good thermal stability;
Anorthite brick	1200-1300	Mainly composed of CaO•Al2O3•SiO2; low bulk density; good resistance to cracking;
Alumina bubble brick	1350-1500	Made by the bubbling method; mainly used for the insulation of furnaces.