- Fire brick
A fire brick, firebrick, or refractory brick is a block of refractory
ceramicmaterial used in lining furnaces, kilns, fireboxes, and fireplaces.
brickis built primarily to withstand high heat, but should also usually have a low thermal conductivityto save energy. 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 a natural gasfired kiln, more porous bricks are a better choice. They are weaker, but they are much lighter, easier to form, and insulate far better than dense bricks. In any case, firebricks should not spallunder rapid temperature change, and their strength should hold up well during rapid temperature changes.
To make firebrick,
fireclayis baked in the kiln until it is partly vitrified, and for special purposes may also be glazed. Fire bricks usually contain 30-40% aluminum oxideor alumina and 50% silicon dioxideor silica. They can also be made of chamotte and other materials. For bricks of extreme refractory character, the aluminum oxide content can be as high as 50-80% (with correspondingly less silica), and silicon carbidemay also be present. The standard size of fire-brick is 9 x 4.5 x 2.5 in. (228 mm x 115 mm x 64 mm)
The silica firebricks that line
steel-making furnaces are used at temperatures up to 1650°C (3000°F), which would melt many other types of ceramic, and in fact part of the silica firebrick liquefies. HRSI, a material with the same composition, is used to make the insulating tiles of the space shuttle.
A range of other materials find use as firebricks for lower
temperatureapplications. Magnesium oxideis often used as a lining for furnaces.
The first application of silica "tiles" within ceramic brick kilns or furnaces is credited to William Harry of the
Swansea Valley, Glamorganshire, Walesin 1817. Harry's invention served to vitrify the interior surface of ceramic brick built blast furnace. In 1820however Quakerentrepreneur William Weston Youngbegan experimenting with silica clay recipes, at his pottery in Nantgarw, also in Glamorganshire, for the creation of a robust, heat-proof brick from which a whole blast furnacecould durably be made.
1822, Young, with three further investors, including David Morgan, John Player and (Young's brother) Joseph Young established "The Dinas Firebrick Co." in the Vale of Neath, Glamorganshire, Walesand the first batches of firebricks began to be exported for the construction of blast furnacesacross the industrialized world.
The Welsh word "Dinas," a reference to the hill where the silica was quarried in the upper Neath Valley, (Craig-y-Dinas, at
Pontneddfechan) is synonymous with the word firebrick in many foreign languages, as a result of the extensive influence of this industry in South Wales.
Silica bricks were also manufactured in the upper
Swansea Valleyby the PenwylltDinas Silica Brick Co.
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