What Are Refractory Bricks And What Are They Used For?

 Ranging from yellow, to gray, to traditional red and orange, bricks are found everywhere in many of our cities and are used extensively in construction. In short, the traditional brick manufacturing process involves shaping the clay and firing it in an oven to facilitate the creation of solid blocks, perforated blocks, cobogós, tiles and other shapes. Ceramic tiles are inexpensive; easy to find; highly resistant, thermally inert and glossy; and do not require such specialised labour to construct. However, if installed close to a high heat source, ordinary bricks will eventually crack, making refractory bricks more suitable. But what does this mean?

 

What are refractory bricks?

A fire brick, firebrick, or refractory is a block of ceramic material used in lining furnaces, kilns, fireboxes, and fireplaces. A refractory brick is built primarily to withstand high temperature, but will also usually have a low thermal conductivity for greater energy efficiency. Usually dense firebricks are used in applications with extreme mechanical, chemical, or thermal stresses, such as the inside of a wood-fired kiln or a furnace, which is subject to abrasion from wood, fluxing from ash or slag, and high temperatures. In other, less harsh situations, such as in an electric- or natural gas-fired kiln, more porous bricks, commonly known as "kiln bricks", are a better choice.

 

High Alumina Bricks

Manufacturing Process of Fire Brick

The manufacturing process of fire brick is similar to ordinary bricks. The usual steps are

Digging

Weathering

Tempering

Moulding

Burning

 

Fire bricks are produced from fire clay. The burnings are carried out in a superior type of kiln under carefully graduated temperature control. Processes of burning and cooling are kept rather slow.

 

What are refractory bricks used for?

It seems paradoxical that materials that burn in ovens at temperatures in excess of 1000°C cannot withstand high temperatures. In fact, the main problem is thermal shock. When ordinary brick comes into contact with a heat source, it expands rapidly.

 

When the source stops (e.g. the fire goes out), the material contracts. These sudden changes in temperature can affect the stability of the structure and can create cracks and other serious problems. Refractory materials are those that can withstand high temperatures without destroying their structure, resistance or thermal conductivity. In the case of bricks, the chemical composition of refractory materials differs from that of ordinary bricks, and this can also affect their colour and thermal conductivity.

Straight Fireclay Bricks

For domestic use, such as ovens, barbecues and fireplaces, the refractory bricks used are usually composed of clay containing mainly aluminium oxide and silica, elements that can withstand high temperatures. While alumina has reflective properties, silica is an excellent insulator. The more alumina present in the mix, the higher the temperature the brick can withstand (a fundamental consideration for industrial use) and the more expensive the brick will be. Silicon dioxide has a lighter colour, while aluminium oxide has a more yellowish appearance.

 

In addition to their technical function, there are architects who use exposed refractory bricks to build and coat surfaces.

 

In addition to the bricks themselves, the mortar used must also be able to withstand high temperatures. It is therefore usually made up of special aggregates such as vermiculite and refractory clay. Like brick, it can also contain aluminium oxide (Al2O3), mullite-zirconium oxide and other materials.

 

It is always important to emphasise that when designing or constructing structures that come into contact with fire, care must be taken to use materials that are consistent with local regulations. This caution comes at a small price in order to avoid material damage or more serious accidents. It is always essential to seek the advice of experts and manufacturers.

The source is from here.