Editing Rust (section)

{{Short description|Type of iron oxide}}
{{About|the chemical compound|other uses|Rust (disambiguation)}}

[[File:Rust on iron.jpg|thumb|upright=1.35|Colors and porous surface texture of rust]]
{{Steels}}
'''Rust''' is an [[iron oxide]], a usually reddish-brown [[oxide]] formed by the reaction of [[iron]] and [[oxygen]] in the [[catalytic]] presence of [[water]] or [[air moisture]]. Rust consists of [[hydrous ferric oxides|hydrous iron(III) oxide]]s (Fe<sub>2</sub>O<sub>3</sub>·nH<sub>2</sub>O) and [[iron(III) oxide-hydroxide]] (FeO(OH), Fe(OH)<sub>3</sub>), and is typically associated with the [[corrosion]] of [[refined iron]].

Given sufficient time, any iron mass, in the presence of water and oxygen, could eventually convert entirely to rust. Surface rust is commonly flaky and [[friable]], and provides no [[passivation (chemistry)|passivation]]al protection to the underlying iron unlike other metals such as aluminum, [[copper]], and [[tin]] which form stable oxide layers. ''Rusting'' is the common term for [[corrosion]] of elemental iron and [[ferroalloy|its alloy]]s such as [[steel]]. Many other [[metal]]s undergo similar corrosion, but the resulting oxides are not commonly called "rust".<ref>{{cite web |title=Rust, n.1 and adj. |url=https://www.oed.com/view/Entry/169112 |website=OED Online |publisher=Oxford University Press |access-date=7 July 2018 |language=en |date=June 2018}}</ref>

Several forms of rust are distinguishable both visually and by [[spectroscopy]], and form under different circumstances.<ref>{{cite web|url=http://nasa.gov/centers/ames/multimedia/audio/MER/mer13.html|title=Interview, David Des Marais|work=NASA|date=2003|url-status=live|archive-url=https://web.archive.org/web/20071113202732/http://nasa.gov/centers/ames/multimedia/audio/MER/mer13.html|archive-date=2007-11-13}}</ref> Other forms of rust include the result of reactions between iron and [[chloride]] in an environment deprived of oxygen. [[Rebar]] used in underwater [[concrete]] [[column|pillars]], which generates [[green rust]], is an example. Although rusting is generally a negative aspect of iron, a particular form of rusting, known as ''stable rust'', causes the object to have a thin coating of rust over the top; this results from reaction with atmospheric oxygen. If kept free of moisture, it makes the "stable" layer protective to the iron below, but not to the extent of other oxides such as [[aluminium oxide]] on [[aluminium]].<ref>{{Cite web|url=http://www.depotwijzer.be/sites/default/files/files/rust_never_sleeps.pdf|title=Rust Never Sleeps: Recognizing Metals and Their Corrosion Products|last1=Ankersmit|last2=Griesser-Stermscheg|last3=Selwyn|last4=Sutherland|first1=Bart|first2=Martina|first3=Lindsie|first4=Susanne|website=depotwijzer|publisher=Parks Canada|access-date=23 July 2016|url-status=live|archive-url=https://web.archive.org/web/20160809005011/http://www.depotwijzer.be/sites/default/files/files/rust_never_sleeps.pdf|archive-date=9 August 2016}}</ref>