Firebricks are blocks of refractory ceramic materials used to line fireplaces, fire boxes and furnaces. They are different from regular masonry bricks because of their ability to withstand temperatures up to 1,800 degrees Fahrenheit. The chemical composition of dense firebricks is different from that of regular bricks. The color, shape and thermal conductivity of firebricks and regular bricks are also different.
Firebricks contain refractory properties. They are also known as fireplace bricks. They are used in building cooking chambers in wood-fired ovens, fire boxes and for creating fireplaces. They are also used to line small or large industrial furnaces. They are heavy and have low porosity. Regular, or masonry, bricks, on the other hand, are more porous. Ordinary bricks begin to decompose at 1,200 degrees Fahrenheit.
The chemical composition of a firebrick includes 23 percent alumina and 73 percent silica. Ferric oxide, titanium and other metallic oxides form the remaining portion. The major chemical composition of regular brick is silica, alumina, magnesia, lime, iron oxide and alkalies. If more or less than the required amount of any of these constituents exist, it may cause serious damage to the brick. The composition is lightly bonded in the case of regular bricks, whereas firebricks are much more dense.
Color and Shape
The firebrick is naturally white. Stains are mixed into the slurry to tint the brick during the manufacturing process. Some of the more popular colors include espresso, mossy green, red and jet black. The color allows the bricks to match the surrounding applications in the same way regular bricks are manufactured in different colors. The color of regular bricks varies according to the type of soil used. Firebricks are uniformly rectangular, while regular bricks may be unevenly shaped.
Thermal conductivity of regular bricks is much higher than with fire bricks. Firebricks can withstand high temperature because the ceramic, ferric oxide and other chemical additives absorb, and do not transfer, high temperatures. The low thermal conductivity offers greater energy efficiency and insulating value. Dense firebricks are therefore used in environments with extreme mechanical or thermal stress. A wood-fired kiln or a furnace are some of the applications that require firebricks. The denser properties also give the brick greater resistance to damage from abrasion. Regular bricks are not suited for these applications.