Mullite Brick

Mullite brick refers to a high alumina refractory material with mullite as the main crystal phase. Generally, the alumina content is between 65% and 75%. Mineral composition In addition to mullite, those with lower alumina content also contain a small amount of glass phase and cristobalite; those with higher alumina content also contain a small amount of corundum.

Mullite Brick Performance

  1. Good high temperature strength & Good thermal shock resistance.
  2. Resistance to most chemical attack & With excellent stability in acid metal slags.
  3. Resistance to oxidation and attack by furnace atmospheres.
  4. Resistance to abiasion and Good electrical resistivity.
  5. Excellent thermal stability and Maximum service temperature 1700˚C.

Mullite Brick Images

mullite brick
mullite brick
mullite brick
mullite brick

Mullite Brick Production Process

Selection and preparation of raw materials: The raw materials typically include high-purity alumina and high-purity silica. The raw materials may be crushed, ground and blended to achieve the desired composition.

Forming: The Mullite brick can be formed using different methods including extrusion, casting, and dry pressing.

Drying: After forming, the bricks are dried to remove any moisture before firing.

Firing: The bricks are fired at high temperatures to achieve the desired chemical and physical properties. This process is usually carried out in a rotary kiln or tunnel kiln.

Cooling: After firing, the bricks are cooled gradually to prevent cracking or damage.

Testing: The finished bricks may be subjected to various tests including physical, chemical and thermal testing to ensure they meet the required standards.

Mullite Brick Specifications

Al2O3 (%)≥60≥65≥65≥70
SiO2 (%)≤35≤33≤26≤24
Fe2O3 (%)≤1.0≤1.0≤0.6≤0.4
Apparent Porosity (%)≤17≤17≤17≤18
Bulk Density, g/cm3≥2.55≥2.55≥2.55≥2.55
Cold Crushing Strength, Mpa≥60≥60≥60≥80
0.2Mpa Refractoriness Under Load T0.6 ℃≥1580≥1600≥1600≥1650
Permanent Linear Change On Reheating,%
Thermal Shock Resistances 100℃ water cycles≥18≥18≥18≥18
20-1000℃ Thermal Expansich10-6/℃
Thermal Conductivity (W/MK) 1000℃1.741.841.951.95

Mullite Brick Raw Material

The raw materials used in the production of mullite bricks include high-purity alumina powder and silica powder. These raw materials are mixed together in a precise ratio to form a homogenous mixture that is then shaped into bricks using a molding machine. The shaped bricks are then fired at a high temperature, which results in the transformation of the raw materials into mullite crystals.


The mullite brick adopts the imported plate corundum and high-purity fused corundum as the main raw materials, and adopts advanced ultrafine powder addition technology. After mixing, drying and forming, it is fired in a high-temperature shuttle kiln. So Mullite bricks are widely used in slag gasification furnaces, synthetic ammonia conversion furnaces, carbon black reactors, and refractory kiln furnaces, Furnace roof of hot blast stove, Furnace stack and bottom of blast furnace,Regenerative chamber of glass melting furnace and Ceramic high temperature furnace.