Fire brick - wikipedia Fire brick `` Firebrick '' redirects here. For the communities in the United States, see Firebrick, California and Firebrick, Kentucky. Refractory bricks in a torpedo car used for hauling molten iron A fire brick, firebrick, or refractory brick is a block of refractory 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. They are weaker, but they are much lighter, easier to form, and insulate far better than dense bricks. In any case, firebricks should not spall, and their strength should hold up well during rapid temperature changes. Contents 1 Manufacture 2 Composition 3 High temperature applications 4 Lower temperature applications 5 See also 6 References Manufacture In the making of firebrick, fireclay is fired in the kiln until it is partly vitrified, and for special purposes may also be glazed. There are two standard sizes of fire - brick ; one is 9 × 41⁄2 × 3 inches ( 229 × 114 × 76 mm ) and the other is 9 × 41⁄2 × 21⁄2 inches ( 229 × 114 × 64 mm ). Also available are firebrick `` splits '' which are half the thickness and are often used to line wood stoves and fireplace inserts. The dimensions of a split are usually 9 × 41⁄2 × 11⁄4 inches ( 229 × 114 × 32 mm ). Fire brick was first invented in 1822 by William Weston Young in the Neath Valley of Wales. Composition Main article : Fire Clay Fire bricks have an aluminium oxide content that can be as high as 50 -- 80 % ( with correspondingly less silica ). High temperature applications The silica firebricks that line steel - making furnaces are used at temperatures up to 1648 ° C ( 3000 ° F ), which would melt many other types of ceramic, and in fact part of the silica firebrick liquefies. High - temperature Reusable Surface Insulation ( HRSI ), a material with the same composition, was used in the insulating tiles of the Space Shuttle. Non-ferrous metallurgical processes use basic refractory bricks because the slags used in these processes readily dissolve the `` acidic '' silica bricks. The most common basic refractory bricks used in smelting non-ferrous metal concentrates are `` chrome - magnesite '' or `` magnesite - chrome '' bricks ( depending on the relative ratios of magnesite and chromite ores used in their manufacture ). Lower temperature applications A range of other materials find use as firebricks for lower temperature applications. Magnesium oxide is often used as a lining for furnaces. Silica bricks are the most common type of bricks used for the inner lining of furnaces and incinerators. As the inner lining is usually of sacrificial nature, fire bricks of higher alumina content may be employed to lengthen the duration between re-linings. Very often cracks can be seen in this sacrificial inner lining shortly after being put into operation. They revealed more expansion joints should have been put in the first place, but these now become expansion joints themselves and are of no concern as long as structural integrity is not affected. Silicon carbide, with high abrasive strength, is a popular material for hearths of incinerators and cremators. Common red clay brick are used for chimneys and wood - fired ovens. See also Harbison - Walker Refractories Company Equivalent VIII Niles Firebrick References Jump up ^ Insulating fire bricks, retrieved 2016 - 08 - 07 Jump up ^ http://www.vitcas.com/refractory-bricks Refractory bricks Jump up ^ Modern Refractory Practice, Fifth Edition ( Harbison -- Walker Refractories : Pittsburgh, Pennsylvania, 1992 ), Page CR - 2 Jump up ^ Modern Refractory Practice, Fifth Edition ( Harbison -- Walker Refractories : Pittsburgh, Pennsylvania, 1992 ), Page CR - 3 Jump up ^ Refractory Engineering. Die Deutsche Bibliothek. 2004. ISBN 3 - 8027 - 3155 - 7. Retrieved from `` https://en.wikipedia.org/w/index.php?title=Fire_brick&oldid=832008220 '' Categories : Bricks Refractory materials Silicates Hidden categories : All articles with unsourced statements Articles with unsourced statements from September 2013 Articles with unsourced statements from July 2016 Talk Contents About Wikipedia Català Español Euskara Français 한국어 हिन्दी Hrvatski Português Română Русский Srpskohrvatski / српскохрватски Українська 中文 4 more Edit links This page was last edited on 23 March 2018, at 08 : 13. Text is available under the Creative Commons Attribution - ShareAlike License ; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia ® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization. About Wikipedia

Question: why is silica used to make bricks for high temperature furnaces
Answer: at temperatures up to 1648°C (3000°F), which would melt many other types of ceramic