"rust. Only iron or alloys that contain iron can rust, but other metals can corrode in similar ways. The main catalyst for the rusting process is water. Iron or steel structures might appear to be solid, but water molecules can penetrate the microscopic pits and cracks in any exposed metal. The hydrogen atoms present in water molecules can combine with other elements to form acids, which will eventually cause more metal to be exposed. If chloride ions are present, as is the case with saltwater, the corrosion is likely to occur more quickly. Meanwhile, the oxygen atoms combine with metallic"
"take up more volume than the original metal; this expansion can generate enormous forces, damaging structures made with iron. See ""economic effect"" for more details. The rusting of iron is an electrochemical process that begins with the transfer of electrons from iron to oxygen. The iron is the reducing agent (gives up electrons) while the oxygen is the oxidising agent (gains electrons). The rate of corrosion is affected by water and accelerated by electrolytes, as illustrated by the effects of road salt on the corrosion of automobiles. The key reaction is the reduction of oxygen: Because it forms hydroxide ions,"
"Iron(III) oxide Iron(III) oxide or ferric oxide is the inorganic compound with the formula FeO. It is one of the three main oxides of iron, the other two being iron(II) oxide (FeO), which is rare, and iron(II,III) oxide (FeO), which also occurs naturally as the mineral magnetite. As the mineral known as hematite, FeO is the main source of iron for the steel industry. FeO is readily attacked by acids. Iron(III) oxide is often called rust, and to some extent this label is useful, because rust shares several properties and has a similar composition. To a chemist, rust is considered"
"from the seawater penetrate the iron on the molecular level. When in solution, these chlorides present no real problem. However, when exposed to air, they slowly dry in crystal form. As the crystals grow, the surface of the metal will expand and flake away, eventually reducing the artifact to a pile of iron oxide dust."" In other words, the iron oxide dust is called rust. Rust occurs naturally on iron when it has been submerged for a while and is exposed to oxygen. Concretion is an encrusted layer of sand, sediment and shells that builds up slowly, when an object"
"solution. The solution detects both Fe ions and hydroxyl ions. Formation of Fe ions and hydroxyl ions are indicated by blue and pink patches respectively. Because of the widespread use and importance of iron and steel products, the prevention or slowing of rust is the basis of major economic activities in a number of specialized technologies. A brief overview of methods is presented here; for detailed coverage, see the cross-referenced articles. Rust is permeable to air and water, therefore the interior metallic iron beneath a rust layer continues to corrode. Rust prevention thus requires coatings that preclude rust formation. Stainless"
"illustrates the low solubility of ferric ions in water. Various reagents cause rust to dissolve even at neutral pH. These ligands include EDTA, which forms a chelate complex with the ion, displacing the hydroxide and oxide ligands that comprise rust. For this reason, EDTA is often used to dissolve iron deposits or to deliver soluble iron in fertilizers. Citrate also solubilizes ferric ion at neutral pH, although its complexes are less stable than those of EDTA. Ferric iron is a d center, meaning that the metal has five ""valence"" electrons in the 3d orbital shell. The magnetism of ferric compounds"
"In comparison, rust, the red oxide of iron (FeO), undergoes an extremely large volume change upon hydration; as a result, the oxide easily flakes off causing the typical reddish rusting away of iron. ""Cold"", ""Hot"", ""Rust Blue"" and ""Fume Blue"" are oxidizing processes simply referred to as bluing. ""Cold"" bluing is generally a selenium dioxide based compound that colours steel black, or more often a very dark grey. It is a difficult product to apply evenly, offers minimal protection and is generally best used for small fast repair jobs and touch-ups. The ""Hot"" process is an alkali salt solution, referred"
"its tensile strength and make the austenite form of the iron-carbon solution more stable, chromium increases hardness and melting temperature, and vanadium also increases hardness while making it less prone to metal fatigue. To inhibit corrosion, at least 11% chromium is added to steel so that a hard oxide forms on the metal surface; this is known as stainless steel. Tungsten slows the formation of cementite, keeping carbon in the iron matrix and allowing martensite to preferentially form at slower quench rates, resulting in high speed steel. On the other hand, sulfur, nitrogen, and phosphorus are considered contaminants that make"
"Green rust Green rust is a generic name for various green crystalline chemical compounds containing iron(II) and iron(III) cations, the hydroxide () anion, and another anion such as carbonate (), chloride (), or sulfate (), in a layered double hydroxide structure. The most studied varieties are Other varieties reported in the literature are bromide , fluoride , iodide , nitrate , and selenate. Green rust was first recognized as a corrosion crust on iron and steel surfaces. It occurs in nature as the mineral fougerite. The crystal structure of green rust can be understood as the result of inserting the"
"niobium. Additional elements, most frequently considered undesirable, are also important in steel: phosphorus, sulfur, silicon, and traces of oxygen, nitrogen, and copper. Plain carbon-iron alloys with a higher than 2.1% carbon content are known as cast iron. With modern steelmaking techniques such as powder metal forming, it is possible to make very high-carbon (and other alloy material) steels, but such are not common. Cast iron is not malleable even when hot, but it can be formed by casting as it has a lower melting point than steel and good castability properties. Certain compositions of cast iron, while retaining the economies"
"known as rust converter which contain tannic acid or phosphoric acid which combines with rust; removed with organic acids like citric acid and vinegar or the stronger hydrochloric acid; or removed with chelating agents as in some commercial formulations or even a solution of molasses. Rust is associated with degradation of iron-based tools and structures. As rust has a much higher volume than the originating mass of iron, its buildup can also cause failure by forcing apart adjacent parts — a phenomenon sometimes known as ""rust packing"". It was the cause of the collapse of the Mianus river bridge in"
"foreign anions and water molecules between brucite-like layers of iron(II) hydroxide, (). The latter has an hexagonal structure, with layer sequence AcBAcB... , where A and B are planes of hydroxide ions, and c those of (iron(II), ferrous) cations. In the green rust, some cations get oxidized to (iron(III), ferric). Each triple layer AcB, which is electrically neutral in the hydroxide, becomes positively charged. The anions then intercalate between those triple layers and restore neutrality. There are two basic structures of green rust, ""type 1"" and ""type 2"". Type 1 is exemplified by the chloride and carbonate varieties. It has"
"elemental iron, and a large amount of heat. The reactants are commonly powdered and mixed with a binder to keep the material solid and prevent separation. Commonly the reacting composition is five parts iron oxide red (rust) powder and three parts aluminium powder by weight, ignited at high temperatures. A strongly exothermic (heat-generating) reaction occurs that via reduction and oxidation produces a white hot mass of molten iron and a slag of refractory aluminium oxide. The molten iron is the actual welding material; the aluminium oxide is much less dense than the liquid iron and so floats to the top"
"reaction can occur in the process of anaerobic corrosion of iron and carbon steel in various conditions. Anaerobic corrosion of metallic iron to give iron(II) hydroxide and hydrogen: followed by the Schikorr reaction: give the following global reaction: At low temperature, the anaerobic corrosion of iron can give rise to the formation of ""green rust"" (fougerite) an unstable layered double hydroxide (LDH). In function of the geochemical conditions prevailing in the environment of the corroding steel, iron(II) hydroxide and green rust can progressively transform in iron(II,III) oxide, or if bicarbonate ions are present in solution, they can also evolve towards"
"Iron Iron is a chemical element with symbol Fe (from ) and atomic number 26. It is a metal in the first transition series. It is by mass the most common element on Earth, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust. Its abundance in rocky planets like Earth is due to its abundant production by fusion in high-mass stars, where it is the last element to be produced with release of energy before the violent collapse of a supernova, which scatters the iron into space. Like the other"
"alloying elements such as manganese, chromium, nickel, tungsten, and so on. Basically, steel is an iron-carbon alloy that does not undergo eutectic reaction. In contrast, cast iron does undergo eutectic reaction. Too little carbon content leaves (pure) iron quite soft, ductile, and weak. Carbon contents higher than those of steel make a brittle alloy commonly called pig iron. While iron alloyed with carbon is called carbon steel, alloy steel is steel to which other alloying elements have been intentionally added to modify the characteristics of steel. Common alloying elements include: manganese, nickel, chromium, molybdenum, boron, titanium, vanadium, tungsten, cobalt, and"
"Cast iron Cast iron is a group of iron-carbon alloys with a carbon content greater than 2%. Its usefulness derives from its relatively low melting temperature. The alloy constituents affect its colour when fractured: white cast iron has carbide impurities which allow cracks to pass straight through, grey cast iron has graphite flakes which deflect a passing crack and initiate countless new cracks as the material breaks, and ductile cast iron has spherical graphite ""nodules"" which stop the crack from further progressing. Carbon (C) ranging from 1.8–4 wt%, and silicon (Si) 1–3 wt% are the main alloying elements of cast"
"steel forms a passivation layer of chromium(III) oxide. Similar passivation behavior occurs with magnesium, titanium, zinc, zinc oxides, aluminium, polyaniline, and other electroactive conductive polymers. Special ""weathering steel"" alloys such as Cor-Ten rust at a much slower rate than normal, because the rust adheres to the surface of the metal in a protective layer. Designs using this material must include measures that avoid worst-case exposures, since the material still continues to rust slowly even under near-ideal conditions. Galvanization consists of an application on the object to be protected of a layer of metallic zinc by either hot-dip galvanizing or electroplating."
"in period 4, between chromium and iron. Manganese is often found free in nature, but is also found in combination with iron. Manganese, like chromium before it, is an important component in stainless steel, preventing the iron from rusting. Manganese is also often used in pigments, again like chromium. Manganese is also poisonous; if enough is inhaled, it can cause irreversible neurological damage. Iron (Fe) is an element in period 4, between manganese and cobalt. Iron is probably the most well-known element in period 4, being the most common element in the earth and a major component of steel. Iron-56"
"to occur the metal has to be in contact with oxygen and water, although chemical reactions for this process are relatively complex and not all of them are completely understood. It is believed the causes are the following: Electron transfer (reduction-oxidation) Iron corrosion takes place in an acid medium; H ions come from reaction between carbon dioxide in the atmosphere and water, forming carbonic acid. Fe ions oxidizes, following this equation: Iron(III) oxide hydrate is known as rust. The concentration of water associated with iron oxide varies, thus the chemical formula is represented by <chem>2Fe2O3.\mathit{x}H2O</chem>. An electric circuit is formed"
"iron is poured into a holding furnace or ladle. Cast iron's properties are changed by adding various alloying elements, or alloyants. Next to carbon, silicon is the most important alloyant because it forces carbon out of solution. A low percentage of silicon allows carbon to remain in solution forming iron carbide and the production of white cast iron. A high percentage of silicon forces carbon out of solution forming graphite and the production of grey cast iron. Other alloying agents, manganese, chromium, molybdenum, titanium and vanadium counteracts silicon, promotes the retention of carbon, and the formation of those carbides. Nickel"
"was championed by South Carolina Senator Glenn McConnell. He asked Warren Lasch to take on the fundraising and oversee the conservation and restoration treatment of the ""Hunley"". Lasch accepted the challenge in 1997 and became the chairman of the Friends of the Hunley. Rust occurs naturally when iron or steel is submerged in water and exposed to oxygen. It can also occur when the moisture content of the air surrounding the metal is high. Because the ""H.L. Hunley"" was made of iron and was submerged for over a hundred years, rust had formed all over the submarine. However, to prevent"
"less than 0.05%). One analysis gives 0.10% in the slags for 0.18% in the iron itself. This high phosphorus content and particular repartition are essential catalysts in the formation of a passive protective film of misawite (d-FeOOH), an amorphous iron oxyhydroxide that forms a barrier by adhering next to the interface between metal and rust. Misawite, the initial corrosion-resistance agent, was thus named because of the pioneering studies of Misawa and co-workers on the effects of phosphorus and copper and those of alternating atmospheric conditions in rust formation. The most critical corrosion-resistance agent is iron hydrogen phosphate hydrate (FePO-HPO-4HO) under"
"(III) oxide, while the core is bright orange due to the presence of crystals of goethite (a hydrated iron oxide). Rusticle A rusticle is a formation of rust similar to an icicle or stalactite in appearance that occurs deep underwater when wrought iron oxidizes. They may be familiar from underwater photographs of shipwrecks, such as the RMS ""Titanic"" and the German battleship ""Bismarck"". Rusticles are created by microbes that consume iron. The word ""rusticle"" is a portmanteau of the words ""rust"" and ""icicle"" and was coined by Robert Ballard, who first observed them on the wreck of the ""Titanic"" in"
"Rust converter Rust converters are chemical solutions or primers that can be applied directly to an iron or iron alloy surface to convert iron oxides (rust) into a protective chemical barrier. These compounds interact with iron oxides, especially iron(III) oxide, converting them into an adherent black layer that is more resistant to moisture and protects the surface from further corrosion. They are sometimes referred to as ""rust remover"" or ""rust killer"". Commercial rust converters are water-based and contain two primary active ingredients: Tannic acid and an organic polymer. Tannic acid chemically converts the reddish iron oxides into bluish-black ferric tannate,"
"steel, commonly zinc, aluminium, or magnesium. The sacrificial anode will eventually corrode away, ceasing its protective action unless it is replaced in a timely manner. Cathodic protection can also be provided by using a special-purpose electrical device to appropriately induce an electric charge. Rust formation can be controlled with coatings, such as paint, lacquer, varnish, or wax tapes that isolate the iron from the environment. Large structures with enclosed box sections, such as ships and modern automobiles, often have a wax-based product (technically a ""slushing oil"") injected into these sections. Such treatments usually also contain rust inhibitors. Covering steel with"
"suspension must have a slight excess of (in the ratio of 0.5833 for each ) for the green rust to form; however, too much of it will produce instead an insoluble basic iron sulfate, iron(II) sulfate hydroxide ()·""n"". The production of green rust is reduced as temperature increases. An alternate preparation of carbonate green rust first creates a suspension of iron(III) hydroxide () in an iron(II) chloride solution, and bubbles carbon dioxide through it. In a more recent variant, solutions of both iron(II) and iron(III) salts are first mixed, then a solution of is added, all in the stoichometric proportions"
"grew until the part failed. The fracture surface shows iron and calcium salts that were deposited in the leaking joint from the water supply before failure. The element iron can combine with chlorine at high temperatures in a strong exothermic reaction, creating a ""chlorine-iron fire"". Chlorine-iron fires are a risk in chemical process plants, where much of the pipework that carries chlorine gas is made of steel. Chlorine Chlorine is a chemical element with symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly"
"in turn prevents eutrophication. In water, iron forms compounds that are often insoluble, at least near neutral pH. A salt of iron hydrolyzes water and produces iron(III) oxide-hydroxides while contributing hydrogen ions to the solution, lowering the pH. In contrast, typical Na salts (e.g. NaCl) dissolve in water without lowering the pH. The differing behavior of Na vs Fe ions reflects the effect of charge: water when bound to Fe is highly acidic, inducing the formation of iron(III) hydroxides, which polymerize via the process called olation. Aluminium(III) (Al) behaves similarly to ferric ion. Rust, a mixture of ferric hydroxide compounds,"
"Iridium Iridium is a chemical element with symbol Ir and atomic number 77. A very hard, brittle, silvery-white transition metal of the platinum group, iridium is the second-densest metal (after osmium) with a density of as defined by experimental X-ray crystallography. However at room temperature and standard atmospheric pressure, iridium has a density of , higher than osmium measured the same way. It is the most corrosion-resistant metal, even at temperatures as high as 2000 °C. Although only certain molten salts and halogens are corrosive to solid iridium, finely divided iridium dust is much more reactive and can be flammable."
"of water concomitantly reduced in molecular hydrogen (). The anaerobic corrosion of iron leads first to the formation of ferrous hydroxide (green rust) and can be described by the following reaction: In its turn, under anaerobic conditions, the ferrous hydroxide () can be oxidized by the protons of water to form magnetite and molecular hydrogen. This process is described by the Schikorr reaction: The well crystallized magnetite () is thermodynamically more stable than the ferrous hydroxide (). This process occurs during the anaerobic corrosion of iron and steel in oxygen-free groundwater and in reducing soils below the water table. In"
"iron(III)-bearing mineral phases in soil analyses (selective extraction). The decomposition of dithionite produces reduced species of sulfur that can be very aggressive for the corrosion of steel and stainless steel. Thiosulfate () is known to induce pitting corrosion, whereas sulfide (S, HS) is responsible for stress corrosion cracking (SCC). Dithionite The dithionite anion ([SO]), is an oxoanion of sulfur. It is commonly encountered as colorless salts. Dithionite is a reducing agent. At pH 7, the potential is −0.66 V vs NHE. Redox occurs with formation of sulfite: Dithionite undergoes acid hydrolytic disproportionation to thiosulfate and bisulfite: It also undergoes alkaline"
"Given Zane's reputation for keeping abreast of the latest developments, the technique was probably unknown to the ironmasters of Virginia and Pennsylvania. Phosphorus is a deleterious contaminant because it makes steel brittle, even at concentrations of as little as 0.6%. Phosphorus cannot be easily removed by fluxing or smelting, and so iron ores must generally be low in phosphorus to begin with. Small amounts of aluminium (Al) are present in many ores including iron ore, sand and some limestones. The former can be removed by washing the ore prior to smelting. Until the introduction of brick lined furnaces, the amount"