Editing Refractory (section)

====Acidic refractories====
Acidic refractories are generally impervious to acidic materials but easily attacked by basic materials, and are thus used with acidic slag in acidic environments. They include substances such as [[Silicon dioxide|silica]], [[alumina]], and [[fire clay]] brick refractories. Notable reagents that can attack both alumina and silica are hydrofluoric acid, phosphoric acid, and fluorinated gases (e.g. HF, F<sub>2</sub>).<ref>{{Cite web|url = http://accuratus.com/alumox.html|title = Accuratus|date = 2013|access-date = November 22, 2014|website = Aluminum Oxide, Al2O3 Ceramic Properties}}</ref> At high temperatures, acidic refractories may also react with limes and basic oxides.

* '''Silica refractories''' are refractories containing more than 93% [[silicon oxide]] (SiO<sub>2</sub>). They are acidic, have high resistance to thermal shock, flux and slag resistance, and high spalling resistance. Silica bricks are often used in the iron and steel industry as furnace materials. An important property of silica brick is its ability to maintain hardness under high loads until its fusion point.<ref name="IspatGuru" /> Silica refractories are usually cheaper hence easily disposable. New technologies that provide higher strength and more casting duration with  less silicon oxide (90%)  when mixed with organic resins have been developed.  
* '''Zirconia refractories''' are refractories primarily composed of [[Zirconium dioxide|zirconium oxide]] (ZrO<sub>2</sub>). They are often used for glass furnaces because they have low thermal conductivity, are not easily wetted by molten glass and have low reactivity with molten glass. These refractories are also useful for applications in high temperature construction materials.
* '''Aluminosilicate refractories''' mainly consist of [[alumina]] (Al<sub>2</sub>O<sub>3</sub>) and silica (SiO<sub>2</sub>). Aluminosilicate refractories can be semiacidic, fireclay composite, or high alumina content composite.{{clarify|date=May 2020}}<ref>{{Cite book|last=Poluboiarinov|first=D. N.|title=Vysokoglinozemistye keramicheskie i ogneupornye materialy|year=1960|location=Moscow}}</ref>