Fire brick

2025-10-04T16:36:21Z

2600:1017:B83A:73DD:5DD9:1B06:41AD:E7D3: /* Material properties */

{{Short description|Building material}}
{{redirect|Firebrick|the communities in the United States|Firebrick, Ohio|and|Firebrick, Kentucky}}
[[File:Torpedo car refractory bricks.JPG|thumb|Refractory bricks in a [[torpedo wagon|torpedo car]] used for hauling molten iron]]

A '''fire brick''', '''firebrick''', '''fireclay brick''', or '''[[refractory]] brick''' is a block of [[ceramic]] material used in lining [[Metallurgical furnace|furnace]]s, [[kiln]]s, [[firebox (steam engine)|fireboxes]], and [[fireplace]]s. Made of primarily oxide materials like silica and alumina in varying ratios,<ref name=sadik>{{cite journal |last1= Sadik Monteiro|first1= Chaouki|last2= El Amrani|first2= Iz-Eddine|last3= Albizane|first3= Abderrahman|date= 2014|title= Recent advances in silica-alumina refractory: A review|url= https://www.sciencedirect.com/science/article/pii/S218707641400027X|journal= Journal of Asian Ceramic Societies|volume= 2|issue = 2|pages= 83–96|doi=10.1016/j.jascer.2014.03.001|access-date=2025-06-11|doi-access= free}}</ref> these [[Thermal insulation|insulating]] materials are able to withstand extremely high temperatures, and have a low [[thermal conductivity]] for greater [[Efficient energy use|energy efficiency]]. Refractory bricks generally range from 25-45% alumina, and ~60% silica, with additional magnesium, calcium, potassium oxides.<ref name=sadik/>

Usually dense fire bricks 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.<ref name=tradoven>{{cite web
|url= http://www.traditionaloven.com/articles/81/insulating-fire-bricks |title= Insulating fire bricks |access-date= 2016-08-07
}}</ref> They are weaker, but they are much lighter and easier to form and [[thermal insulation|insulate]] far better than dense bricks. In any case, firebricks should not [[spall]], and their strength should hold up well during rapid temperature changes.

==Manufacturing==
There are three main manufacturing methods for firebrick: firing, cementing and geopolymerization.<ref name=sergio>{{cite journal |last1= Neves Monteiro|first1= Sergio|last2= Fontes Vieira|first2= Carlos Mauricio|date= 2014|title= On the production of fired clay bricks from waste materials: A critical update|url= https://www.sciencedirect.com/science/article/abs/pii/S0950061814007211|journal= Construction and Building Materials|volume= 68|pages= 599–610|doi=10.1016/j.conbuildmat.2014.07.006|access-date=2025-06-11|url-access= subscription}}</ref> In the first method, clay is fired in the kiln until it is partly [[Glass transition|vitrified]]. For special purposes, the brick may also be glazed. Firing is the most conventional process, with easy execution using traditional equipment. However, it is an energy intensive process, consuming a significant amount of energy - on the scale of 2.0 kWh per brick. Firing also releases around 0.41 kg of CO<sub>2</sub><ref name=sergio/> from the decomposition of carbonate materials and combustion of fuel.

To cement, refractory brick is combined with refractory [[cement]]. [[Portland cement]] is not able to withstand high temperatures and is therefore not recommended.<ref name=zhang>{{cite journal |last1= Zhang|first1= Lianyang|date= 2013|title= Production of bricks from waste materials – A review|url= https://www.sciencedirect.com/science/article/abs/pii/S0950061813004418|journal= Construction and Building Materials|volume= 47|pages= 643–655|doi=10.1016/j.conbuildmat.2013.05.043|access-date=2025-06-11|url-access= subscription}}</ref> High-temperature refractory cements include furnace cements or high-heat mortar. These mixtures are applied to the brick surfaces and pressed together, and allowed to cure with time - taking anywhere from days to weeks.

A technique with the potential to replace firing and cementing is [[geopolymer]]ization. Firing and cementing both require huge amounts of energy and release large amounts of greenhouse gases, thus motivating research into additional methods of production. Efforts to incorporate up to 30 wt% of waste materials into clay ceramics have been shown. Clay ceramics with 17 wt% additives displayed the highest bending [[Strength of materials|strength]] of 30 MPa.<ref name=sergio/> Although these waste materials are inert, they could be responsible for structural defects that change the material properties and therefore applications of these bricks.

There are two standard sizes of fire brick: {{cvt|9|x|4+1/2|x|3|in|order=flip}} and {{cvt|9|x|4+1/2|x|2+1/2|in|order=flip}}.<ref name=sheffield>{{Cite web|title=Refractory Fire Bricks {{!}} Kiln Building Fire Brick|url=https://www.sheffield-pottery.com/Kiln-Building-Refractory-Bricks-s/24.htm|access-date=2020-07-18|website=www.sheffield-pottery.com}}</ref> 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 {{cvt|9|x|4+1/2|x|1+1/4|in|order=flip}}.<ref name=sheffield /> Fire brick was first invented in 1822 by [[William Weston Young]] in the [[Neath Valley]] of [[Wales]].

==High temperature applications==
The [[Silicon dioxide|silica]] fire bricks that line [[steel]]-making [[Metallurgical furnace|furnace]]s are used at temperatures up to {{cvt|3000|F|0|order=flip}}, which would melt many other types of ceramic, and in fact part of the silica firebrick liquefies.{{citation needed|date=July 2016}} [[Space Shuttle thermal protection system#High-temperature reusable surface insulation (HRSI)|High-temperature Reusable Surface Insulation (HRSI)]], a material with the same composition, was used in the insulating tiles of the [[Space Shuttle]].{{citation needed|date=July 2016}}

Non-ferrous metallurgical processes use [[Refractory#Basic refractories|''basic'' refractory bricks]] because the slags used in these processes readily dissolve the "acidic" silica bricks.<ref>''Modern Refractory Practice, Fifth Edition'' (Harbison–Walker Refractories: Pittsburgh, Pennsylvania, 1992), Page CR-2</ref> 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).<ref>''Modern Refractory Practice, Fifth Edition'' (Harbison–Walker Refractories: Pittsburgh, Pennsylvania, 1992), Page CR-3</ref>

==Lower temperature applications==
A range of other materials find use as firebricks for lower [[temperature]] applications.<ref>{{Cite web|title=Firebricks High Temperature Resistant|url=https://www.vitcas.com/prd/cty/firebricks|access-date=2023-06-21|website=www.vitcas.com}}
</ref> [[Magnesium oxide]] is often used as a lining for [[Metallurgical furnace|furnace]]s. Silica bricks are the most common type of bricks used for the inner lining of furnaces and [[incinerator]]s. 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.<ref>{{cite book|publisher=Die Deutsche Bibliothek|title=Refractory Engineering|year=2004|isbn=3-8027-3155-7}}</ref> Silicon carbide, with high abrasive strength, is a popular material for hearths of [[incinerator]]s and [[cremation|cremator]]s. Common red clay brick may be used for chimneys and wood-fired ovens.

==Material properties==
The linear shrinkage of firebrick under compression was found to be around 12.8%.<ref name=hassan>{{cite journal |last1= Hassan|first1= S.B.|last2= Aigbodion|first2= V.S.|date= 2014|title= Effect coal ash on some refractory properties of alumino-silicate (Kankara) clay for furnace lining|url= https://www.sciencedirect.com/science/article/pii/S2314808X14000128#bib19|journal= Egyptian Journal of Basic and Applied Sciences|volume= 1|issue = 2|pages= 107–114|doi=10.1016/j.ejbas.2014.04.001|access-date=2025-06-11|doi-access= free}}</ref> This number can be decreased to below 8% with the addition of 25wt% [[Coal combustion products|coal ash]]. This is due to the high [[porosity]] of pure refractory bricks, around 31%, which compromise some of its structural integrity. When even 5wt% of coal ash is added, the porosity decreases to 24%,<ref name=hassan /> and can withstand more compressive load. [[Bulk density]] of firebrick is between 1.88-2.05 g/cm^3, which is the approximate standard recommendation for high-temperature applications. This high-density is preferred in order to offer resistance in challenging operating environments. The standard for cold crushing strength is a minimum of 12,000 kN/m^2 for refractory materials.<ref name=hassan />

==Potential use to store energy==
Firebricks, with their ability to withstand high temperatures and store heat, offer a promising solution for storing energy. These refractory bricks can be used to store industrial process heat, leveraging excess renewable electricity to create a low-cost, continuous heat source for industry. Due to their construction from common materials, firebrick storage systems are much more cost-effective than battery systems for thermal energy storage. Research across 149 countries indicates that using firebricks for heat storage can significantly reduce the need for electricity generation, battery storage, hydrogen production, and low-temperature heat storage. This approach could lower overall energy costs by about 1.8%, making firebricks a valuable tool in reducing the costs of transitioning to 100% clean, renewable energy.<ref>{{cite journal |last1=Jacobson |first1=Mark Z |last2=Sambor |first2=Daniel J |last3=Fan |first3=Yuanbei F |last4=Mühlbauer |first4=Andreas |title=Effects of firebricks for industrial process heat on the cost of matching all-sector energy demand with 100% wind–water–solar supply in 149 countries |journal=PNAS Nexus |volume=3 |issue=7 |year=2024 |article-number=pgae274 |doi=10.1093/pnasnexus/pgae274 |doi-access=free|pmc=11263865 }}</ref>

==See also==
* [[Harbison-Walker Refractories Company]]
* [[Equivalent VIII]]
* [[Niles Firebrick]]

== References ==
{{Reflist|30em}}

== Further reading ==
* {{Cite EB1911|wstitle=Firebrick|volume=10|pages=418–419|first1=Joseph|last1=Burton|first2=William|last2=Burton}}

{{DEFAULTSORT:Fire Brick}}
[[Category:Bricks]]
[[Category:Refractory materials]]
[[Category:Silicates]]

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Fire brick