Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Iron corrosion products

Silicates. For many years, siUcates have been used to inhibit aqueous corrosion, particularly in potable water systems. Probably due to the complexity of siUcate chemistry, their mechanism of inhibition has not yet been firmly estabUshed. They are nonoxidizing and require oxygen to inhibit corrosion, so they are not passivators in the classical sense. Yet they do not form visible precipitates on the metal surface. They appear to inhibit by an adsorption mechanism. It is thought that siUca and iron corrosion products interact. However, recent work indicates that this interaction may not be necessary. SiUcates are slow-acting inhibitors in some cases, 2 or 3 weeks may be required to estabUsh protection fully. It is beheved that the polysiUcate ions or coUoidal siUca are the active species and these are formed slowly from monosilicic acid, which is the predorninant species in water at the pH levels maintained in cooling systems. [Pg.270]

Graphitic Corrosion Graphitic corrosion usually involves gray cast iron in which metalhc iron is converted into corrosion products, leaving a residue of intact graphite mixed with iron-corrosion products and other insoluble constituents of cast iron. [Pg.2420]

In oxygenated water of near neutral pH and at or slightly above room temperature, hydrous ferric oxide [FelOHla] forms on steel and cast irons. Corrosion products are orange, red, or brown and are the major constituent of rust. This layer shields the underl3dng metal surface from oxygenated water, so oxygen concentration decreases beneath the rust layer. [Pg.37]

Normal mill coolant pH was near 5. The upset caused large amounts of iron corrosion products to be swept into the coolant. Settling of iron oxides and hydroxides fouled many mill components. [Pg.177]

Dry abrasive blast cleaning should be used on new steelwork where the main contaminant is mill scale. For heavily rusted and pitted steelwork, increased durability can be obtained by the use of wet abrasive blasting where this is practicable. The water will be more effective in removing the potentially destructive and corrosive soluble iron-corrosion products that form at the bottom of corrosion pits. [Pg.134]

The commonest staining trouble is iron stain —the blue-black stain caused by the interaction of soluble iron corrosion products and the natural tannins in wood. Hardwoods are generally more susceptible than softwoods. Steel wool should not be used for smoothing wood surfaces. Iron stains, if not too severe, can be removed with oxalic acid. Heavy contamination with soluble iron corrosion products usually results in migration and conversion to rust deposits in the wood. [Pg.963]

Nail sickness Nail sickness is chemical decay associated with corroded metals in marine situations. Chemical degradation of wood by the products of metal corrosion is brought about by bad workmanship or maintenance, or unsuitable (permeable) timber species, all of which permit electrolyte and oxygen access which promotes corrosion. Chemical decay of wood by alkali occurs in cathodic areas (metal exposed oxygen present). Softening and embrittlement of wood occurs in anodic areas (metal embedded oxygen absent) caused by mineral acid from hydrolysis of soluble iron corrosion products. [Pg.965]

Manson (72,) expanded the concept to the solid state by observing that the strength of composite materials also depended upon the acid-base interaction between continuous and dispersed phases. More directly, Vanderhoff et al. (21) addressed the issue of adhesion of polymeric materials to corroded steel. They synthesized eight corrosion products of iron, and used the interaction scheme developed by Fowkes and Manson first to characterize the iron corrosion products as Lewis acids or bases and then to select polymer vehicles for practical coating systems. Such results were employed to enhance the adhesion of epoxy systems to substrates which were predominantly iron oxide in nature. A good overview of these Issues was presented by Fowkes in 1983 (74). ... [Pg.10]

Kassim, J. Baird,T. Fryer, J.R. (1982) Electron microscope studies of iron corrosion products in water at room temperature. Corrosion ScL 22 147—158... [Pg.595]

Manning, B.A., Hunt, M.L., Amrhein, C., and Yarmoff, J.A., Arsenic(III) and ar-senic(V) reactions with zero-valent iron corrosion products, Environ. Sci. Technol., 36(24), 5455-5461, 2002. [Pg.544]

Silt is formed by suspended particulates of all types that accumulate on the membrane surface. Typical sources of silt are organic colloids, iron corrosion products, precipitated iron hydroxide, algae, and fine particulate matter. A good predictor of the likelihood of a particular feed water to produce fouling by silt is the silt density index (SDI) of the feed water. The SDI, an empirical measurement (ASTM Standard D-4189-82,1987), is the time required to filter a fixed volume of... [Pg.217]

Figure 7.1 Archaeological textile remains preserved in iron corrosion, Macro photograph (a) with scanning electron micrograph (b) (original magnification 2000x). The iron corrosion products have formed a negative cast around the wool fibers prior to their degradation many centuries before examination. (Photo R. C. Janaway.) (See color insert following p. 178.)... Figure 7.1 Archaeological textile remains preserved in iron corrosion, Macro photograph (a) with scanning electron micrograph (b) (original magnification 2000x). The iron corrosion products have formed a negative cast around the wool fibers prior to their degradation many centuries before examination. (Photo R. C. Janaway.) (See color insert following p. 178.)...
Cameron, E. (1991). Identification of skin and leather preserved by iron corrosion products. J. Archaeol. Sci. 18,25-33. [Pg.191]

Keepax, C. (1975). Scanning electron microscopy of wood replaced by iron corrosion products. /. Archaeol. Sci. 2,145-150. [Pg.193]

Silt density index measures suspended solids, particularly colloids, such as alumina- or iron silicates, clay, iron corrosion products, and microbes, that have a great potential for fouling RO membranes (see Chapter 3.8 for more details about SDI). The SDI should be as low as possible to minimize fouling of the membranes, but must be less than 5 to meet warranty requirements set by the membrane manufacturers (best practices call for SDI in RO feed water to be less than 3). Note that there is no direct correlation of turbidity to SDI, other than high turbidity usually means high SDI (the converse is not always true). [Pg.125]

It is noteworthy that the presence of sulfide in the feed liquor to the towers serves to maintain a protective film of iron sulfide on the cast iron equipment, which minimizes the contamination of product crystals from iron corrosion products. [Pg.1187]

Cast Iron Corrosion Products, Stud. Conserv. (1977) 22, 146-157. [Pg.32]

Salts are passively absorbed into wooden objects in seawater, but some ions notably iron(III) are actively bound by cellulose, and high concentrations of iron corrosion products build up in consequence. As the wood becomes anoxic, these salts are converted into sulfides by the activity of SRB. A physical consequence of iron inclusions is that the wood microstructure becomes blocked making the object impermeable to future conservation treatments. Iron sulfide is unstable in the aerobic environment, and its oxidation can destroy the object (Figure 17). [Pg.299]

Dithionites are useful in removing rust stains, and neutral citrate solutions of Na2S204 were used to remove iron corrosion products from objects recovered from the Titanic. [Pg.156]

Dunnwald and Otto [137] found phase transformation of iron corrosion product to Fe(OH)3 in the atmosphere containing SO2 with humidity by Raman spectroscopy. Subsequently, Fe(OH)3 gets transformed to crystalline FeOOH with amorphous FeOOH. It has been shown that the amorphous rust is the primary product of atmospheric corrosion, which later transforms to crystalline forms in the absence of copper. Yamashita et al. [144] smdied the long-term growth of the protective rust layer formed on weathering steel under atmospheric corrosion in an industrial region involving an exposme for 26 years. The outer layer of rust was... [Pg.30]

Preparation of steel substrates before application of paints and related products— Tests for the assessment of surface cleanliness— Part 1 Field test for soluble iron corrosion products... [Pg.857]


See other pages where Iron corrosion products is mentioned: [Pg.132]    [Pg.166]    [Pg.149]    [Pg.194]    [Pg.699]    [Pg.964]    [Pg.71]    [Pg.149]    [Pg.47]    [Pg.147]    [Pg.286]    [Pg.456]    [Pg.458]    [Pg.325]    [Pg.993]    [Pg.469]    [Pg.123]    [Pg.422]    [Pg.227]   
See also in sourсe #XX -- [ Pg.77 , Pg.79 ]




SEARCH



Corrosion products

Iron production

Iron products

Iron: corrosion

© 2024 chempedia.info