What is a refractory brick? Why is it called fire brick?

Refractory bricks are shaped refractory materials that are used in industrial furnaces. The term originates from the refractory material having a specific geometric shape, it resembles a brick in general. Since almost all industrial furnaces reach high temperatures, the refractory brick must be able to stand against the corrosive effect of the heat. That is why they are also called fire bricks. Fire bricks are produced by special methods that allow manufacture of any desired geometric shape. The important thing here is the bonding between the brick and the mortar, which determines the type of the end result. Production methods and the type of mortar used also to determine the area of application of fire bricks. If we make a classification based on this information;

Fire brick types and uses

Composite refractory bricks : These consist of Al2O3 - SiC, Al2O3, MgO, and ZrO2. They can withstand very high temperatures. Therefore, they are often used in the steel industry and electric arc furnaces.

Three oxide refractory bricks : They are made of a mixture of AZS (ZrO2-Al2O3-SiO2) and CAS (CaO-SiO2-Al2O3). Since because they can withstand the effects of the corrosive liquids, they are mostly used in glass melting furnaces.

Silica refractory bricks :  This is one of the most widely used types of fire bricks. They are made from a mixture of quartz and pure calcium oxide. Quartz is transformed into calcium silicate during the production phase. Silica refractory bricks are mainly used in the construction of metallurgical furnaces. Their resistance to acid-based abrasion is high.

Magnesite refractory bricks : They are manufactured from periclase and belong to the basic refractory category. Periclase acts like a mortar and bonds the iron oxide, quartz, and silicate together. It has a high tolerance against basic corrosion. However, their resistance to high temperature is low. They are used in basic furnaces of all types.

Chromite-magnesia refractory bricks   : As the name suggests, they are made from a mixture of magnesite and chromite content. (Mixing ratio is usually 70/30.) They are manufactured with the dry-pressing method. Furnace ceilings and gas outlet pipes are the most common areas of usage.

Dolomite refractory bricks : They are made of dolomite, which is an extremely common material. Dolomite bricks are used in chambers of basic and electric arc furnaces, and over the inner walls.