Pages in category "Corrosion inhibitors"
The following 24 pages are in this category, out of 24 total, this list may not reflect recent changes (learn more).
The following 24 pages are in this category, out of 24 total, this list may not reflect recent changes (learn more).
1. Corrosion inhibitor – A corrosion inhibitor is a chemical compound that, when added to a liquid or gas, decreases the corrosion rate of a material, typically a metal or an alloy. The effectiveness of a corrosion inhibitor depends on composition, quantity of water. A common mechanism for inhibiting corrosion involves formation of a coating, often a passivation layer, permanent treatments such as chrome plating are not generally considered inhibitors, however. Instead corrosion inhibitors are additives to the fluids that surround the metal or related object, the nature of the corrosive inhibitor depends on the material being protected, which are most commonly metal objects, and on the corrosive agent to be neutralized. The corrosive agents are oxygen, hydrogen sulfide, and carbon dioxide. Related inhibitors of oxygen corrosion are hexamine, phenylenediamine, and dimethylethanolamine, antioxidants such as sulfite and ascorbic acid are sometimes used. Some corrosion inhibitors form a coating on the surface by chemisorption. Benzotriazole is one such species used to protect copper, for lubrication, zinc dithiophosphates are common - they deposit sulfide on surfaces. The suitability of any given chemical for a task in hand depends on many factors, volatile amines are used in boilers to minimize the effects of acid. In some cases, the form a protective film on the steel surface and, at the same time. An inhibitor that acts both in a cathodic and anodic manner is termed a mixed inhibitor, benzotriazole inhibits the corrosion and staining of copper surfaces. Corrosion inhibitors are added to paints. A pigment with anticorrosive properties is zinc phosphate, compounds derived from tannic acid or zinc salts of organonitrogens can be used together with anticorrosive pigments. Other corrosion inhibitors are Anticor 70, Albaex, Ferrophos, antiseptics are used to counter microbial corrosion. Benzalkonium chloride is used in oil field industry. In oil refineries, hydrogen sulfide can corrode steels so it is removed often using air, corrosion inhibitors are commonly added to coolants, fuels, hydraulic fluids, boiler water, engine oil, and many other fluids used in industry. For fuels, various corrosion inhibitors can be used, dCI-4A, widely used in commercial and military jet fuels, acts also as a lubricity additive. Can be also used for gasolines and other distillate fuels, dCI-6A, for motor gasoline and distillate fuels, and for U. S
2. Barium borate – Barium borate is an inorganic compound, a borate of barium with a chemical formula BaB2O4 or Ba2. It is available as a hydrate or dehydrated form, as powder or colorless crystals. The crystals exist in the high-temperature α phase and low-temperature β phase, abbreviated as BBO, barium borate exists in two major crystalline forms, alpha and beta. The low-temperature beta phase converts into the alpha phase upon heating to 925 °C, β-Barium borate differs from the α form by the positions of the barium ions within the crystal. Both phases are birefringent, however the α phase possesses centric symmetry, alpha barium borate, α-BaB2O4 is an optical material with a very wide optical transmission window from about 190 nm to 3500 nm. It has good properties and is a suitable material for high-power ultraviolet polarization optics. It can replace calcite, titanium dioxide or lithium niobate in Glan–Taylor prisms, Glan–Thompson prisms, walk-off beam splitters and it has low hygroscopicity, and its Mohs hardness is 4.5. Its damage threshold is 1 GW/cm2 at 1064 nm and 500 MW/cm2 at 355 nm, beta barium borate, β-BaB2O4, is a nonlinear optical material transparent in the range ~190–3300 nm. It can be used for spontaneous parametric down-conversion and its Mohs hardness is also 4.5. Barium borate has strong negative uniaxial birefringence and can be phase-matched for type I second-harmonic generation from 409.6 to 3500 nm, the temperature sensitivity of the indices of refraction is low, leading to an unusually large temperature phase-matching bandwidth. Barium borate can be prepared by reaction of a solution of boric acid with barium hydroxide. The prepared γ-barium borate contains water of crystallization that can not be removed by drying at 120 °C. Dehydrated γ-barium borate can be prepared by heating to 300–400 °C, calcination at about 600–800 °C causes complete conversion to the β form. BBO prepared by this method does not contain trace amounts of BaB2O2 BBO crystals for nonlinear optics can be grown from fluxed melt of barium borate, sodium oxide, thin films of barium borate can be prepared by MOCVD from barium hydro-triborate. Different phases can be obtained depending on deposition temperatures, thin films of beta-barium borate can be prepared by sol-gel synthesis. Barium borate monohydrate is prepared from the solution of barium sulfide and it is used as an additive to e. g. paints as flame retardant, mold inhibitor, and corrosion inhibitor. It is also used as a white pigment, barium borate dihydrate is prepared from the solution of sodium metaborate and barium chloride at 90–95 °C. After cooling to room temperature, white powder is precipitated, barium borate dihydrate loses water at above 140 °C
3. Benzotriazole – Benzotriazole is a heterocyclic compound containing three nitrogen atoms, with the chemical formula C6H5N3. This aromatic compound is colorless and polar and can be used in various fields and its five-membered ring can exist in tautomers A and B, and the derivatives of both tautomers, structures C and D also can be produced. Various structural analyses with UV, IR and 1H-NMR spectra indicated that isomer A is predominantly present at room temperature, the bond between positions 1 and 2 and the one between positions 2 and 3 have proved to have the same bond properties. Moreover, the proton does not tightly bind to any of the nitrogen atoms, therefore, the BTA can lose a proton to act as a weak acid or accept a proton using the lone pair electrons located on its nitrogen atoms as a very weak Bronsted base. Not only can it act either as an acid or base, it can bind to other species. Applying this property, the BTA can form a coordination compound on a copper surface. A synthesis of the BTA involves the reaction of o-phenylenediamine, sodium nitrite, the conversion proceeds via diazotization of one of the amine groups. The synthesis can be improved when the reaction is carried out at low temperatures, typical batch purity is 98. 5% or greater Benzotriazole has been known for its great versatility. It has already used as a restrainer in photographic emulsions. More importantly, it has extensively used as a corrosion inhibitor in the atmosphere. Also, its derivatives and their effectiveness as drug precursors have been drawing attention, besides all the application mentioned above, the BTA can be used as antifreezes, heating and cooling systems, hydraulic fluids and vapor phase inhibitors as well. Benzotriazole is a corrosion inhibitor for copper and its alloys by preventing undesirable surface reactions. It is known that a layer, consisting of a complex between copper and benzotriazole, is formed when copper is immersed in a solution containing benzotriazole. The passive layer is insoluble in aqueous and many organic solutions, there is a positive correlation between the thickness of the passive layer and the efficiency of preventing corrosion. BTA is used in conservation, notably for the treatment of bronze disease, the exact structure of the copper-BTA complex is controversial and many proposals have been suggested. Benzotriazole derivatives have chemical and biological properties that are versatile in the pharmaceutical industry, Benzotriazole derivatives act as agonists for many proteins. The methodology is not only limited to heterocyclization but was successful for polynuclear hydrocarbons of small carbocyclic systems. Trazolopride & Tribendilol are other examples of drugs
4. Cinnamaldehyde – Cinnamaldehyde is an organic compound with the formula C6H5CH=CHCHO. Occurring naturally as predominately the trans isomer, it gives cinnamon its flavor and odor and it is a flavonoid that is naturally synthesized by the shikimate pathway. This pale yellow, viscous liquid occurs in the bark of cinnamon trees, the essential oil of cinnamon bark is about 50% cinnamaldehyde. Cinnamaldehyde was isolated from cinnamon essential oil in 1834 by Dumas and Péligot, the molecule consists of a benzene ring attached to an unsaturated aldehyde. As such, the molecule can be viewed as a derivative of acrolein and its color is due to the π → π* transition, increased conjugation in comparison with acrolein shifts this band towards the visible. The biosynthesis of cinnamaldehyde begins with deamination of L-phenylalalanine into cinnamic acid by the action of phenylalanine ammonia lyase, PAL catalyzes this reaction by a non-oxidative deamination. This deamination relies on the MIO prosthetic group of PAL, PAL gives rise to trans-cinnamic acid. In the second step, 4-coumarate, CoA ligase converts cinnamic acid to cinnamoyl-CoA by an acid-thiol ligation, 4CL uses ATP to catalyze the formation of cinnamoyl-CoA. 4CL effects this reaction in two steps, 4CL forms a hydroxycinnamate-AMP anhydride, followed by a nucleophile attack on the carbonyl of the acyl adenylate. Cinnamoyl-CoA is reduced by NADPH catalyzed by CCR to form cinnamaldehyde, several methods of laboratory synthesis exist, but cinnamaldehyde is most economically obtained from the steam distillation of the oil of cinnamon bark. The compound can be prepared from related compounds such as cinnamyl alcohol, cinnamaldehyde occurs widely, and closely related compounds give rise to lignin. All such compounds are biosynthesized starting from phenylalanine, which undergoes conversion, cinnamoyl-CoA reductase is an enzyme responsible for the production of cinnamoyl-CoA from cinnamaldehyde. The most obvious application for cinnamaldehyde is as flavoring in chewing gum, ice cream, candy and it is also used in some perfumes of natural, sweet, or fruity scents. Almond, apricot, butterscotch, and other aromas may partially employ the compound for their pleasant smells, cinnamaldehyde can be used as a food adulterant, powdered beechnut husk aromatized with cinnamaldehyde can be marketed as powdered cinnamon. Some breakfast cereals contain as much as 187 ppm cinnamaldehyde, cinnamaldehyde is also used as a fungicide. Proven effective on over 40 different crops, cinnamaldehyde is typically applied to the systems of plants. Its low toxicity and well-known properties make it ideal for agriculture, cinnamaldehyde is an effective insecticide, and its scent is also known to repel animals, such as cats and dogs. It has been tested as a safe and effective insecticide against mosquito larvae, a concentration of 29 ppm of cinnamaldehyde kills half of Aedes aegypti mosquito larvae in 24 hours
5. 3,5-Dinitrobenzoic acid – 3, 5-Dinitrobenzoic acid is an organic chemical that is an important corrosion inhibitor and is also used in photography. This aromatic compound is used by chemists to identify alcohol components in esters, saunders, G. J. Stacey, I. G. E. J.1942,36, p. 368–375, Text, PDF
6. Lead(II,IV) oxide – Lead oxide, also called minium, red lead or triplumbic tetroxide, is a bright red or orange crystalline or amorphous pigment. Chemically, red lead is Pb3O4, or 2 PbO·PbO2 and it is used in the manufacture of batteries, lead glass and rust-proof primer paints. Lead oxide has a crystal structure at room temperature, which transforms to an orthorhombic form at temperature 170 K. This phase transition only changes the symmetry of the crystal and slightly modifies the interatomic distances and angles. Lead oxide is prepared by calcination of lead oxide in air at about 450 to 480 °C,6 PbO + O2 →2 Pb3O4 The resulting material is contaminated with lead oxide. g. The best known natural specimens come from Broken Hill, New South Wales, Australia, red lead is virtually insoluble in water and in alcohol. However, it is soluble in hydrochloric acid present in the stomach and it also dissolves in glacial acetic acid and a diluted mixture of nitric acid and hydrogen peroxide. When heated to 500 °C, it decomposes to lead oxide, at 580 °C, the reaction is complete. Lead tetraoxide is most often used as a pigment for primer paints for iron objects, due to its toxicity, its use is being limited. In the past, it was used in combination with linseed oil as a thick, the combination of minium and linen fibres was also used for plumbing, now replaced with PTFE tape. Currently it is used for manufacture of glass, especially lead glass. It finds limited use in amateur pyrotechnics as a delay charge and was used in the past in the manufacture of Dragons eggs pyrotechnic stars. Red lead is used as an agent in some polychloroprene rubber compounds. It is used in place of magnesium oxide to provide better water resistance properties, red lead was also used for engineers scraping, before being supplanted by Engineers blue. When inhaled, lead oxide irritates lungs, in case of high dose, the victim experiences a metallic taste, chest pain, and abdominal pain. When ingested, it is dissolved in the acid and absorbed. High concentrations can be absorbed through skin as well, and it is important to safety precautions when working with lead-based paint. Long-term contact with lead oxide may lead to accumulation of lead compounds in organisms, chronic poisoning displays as agitation, irritability, vision disorders, hypertension, and also a grayish facial hue
7. Oil additive – Oil additives are chemical compounds that improve the lubricant performance of base oil. The manufacturer of different oils can utilize the same base stock for each formulation. Additives comprise up to 5% by weight of some oils, nearly all commercial motor oils contain additives, whether the oils are synthetic or petroleum based. Essentially, only the American Petroleum Institute Service SA motor oils have no additives, Oil additives are vital for the proper lubrication and prolonged use of motor oil in modern internal combustion engines. Without many of these, the oil would become contaminated, break down, leak out, just as important are additives for oils used inside gearboxes, automatic transmissions, and bearings. Some of the most important additives include those used for viscosity and lubricity, contaminant control, for the control of chemical breakdown, some additives permit lubricants to perform better under severe conditions, such as extreme pressures and temperatures and high levels of contamination. Detergent additives, dating back to the early 1930s, are used to clean, corrosion or rust inhibiting additives retard the oxidation of metal inside an engine. Antioxidant additives retard the degradation of the oil by oxidation. Typical additives are organic amines and phenols, metal deactivators create a film on metal surfaces to prevent the metal from causing the oil to be oxidized. Viscosity modifiers make an oils viscosity higher at elevated temperatures, improving its viscosity index and this combats the tendency of the oil to become thin at high temperature. The advantage of using less viscous oil with a VI improver is that it will have improved low temperature fluidity as well as being viscous enough to lubricate at operating temperature, most multi-grade oils have viscosity modifiers. Some synthetic oils are engineered to meet multi-grade specifications without them, viscosity modifiers are often plastic polymers. Pour point depressants improve the ability to flow at lower temperatures. Friction modifiers or friction reducers, like molybdenum disulfide, are used for increasing fuel economy by reducing friction between moving parts, friction modifiers alter the lubricity of the base oil. Extreme pressure agents bond to surfaces, keeping them from touching even at high pressure. Antiwear additives or wear inhibiting additives cause a film to surround metal parts, zinc dialkyldithiophosphate or zinc dithiophosphates are typically used. Wear metals from friction are unintentional oil additives, but most large metal particles and impurities are removed in situ using either magnets or oil filters, tribology is the science that studies how materials wear. Dispersants keep contaminants suspended in the oil to prevent them from coagulating, antimisting agents prevent the atomization of the oil
8. Sodium nitrite – Sodium nitrite is the inorganic compound with the chemical formula NaNO2. It is a white to yellowish crystalline powder that is very soluble in water and is hygroscopic. It is a precursor to a variety of organic compounds, such as pharmaceuticals, dyes, and pesticides. It is on the World Health Organizations List of Essential Medicines, the main use of sodium nitrite is for the industrial production of organonitrogen compounds. It is a reagent for conversion of amines into diazo compounds, nitroso compounds are produced from nitrites. These are used in the rubber industry, other applications include uses in photography. It may also be used as an electrolyte in electrochemical grinding manufacturing processes and it is used in a variety of metallurgical applications, for phosphatizing and detinning. Sodium nitrite is used together with sodium thiosulfate to treat cyanide poisoning and it is in the section antidotes and other substances used in poisonings of the World Health Organizations List of Essential Medicines, the most important medications needed in a basic health system. In the early 1900s, irregular curing was commonplace, through this research, sodium nitrite has been found to inhibit growth of disease-causing microorganisms, give taste and color to the meat, and inhibit lipid oxidation that leads to rancidity. The ability of sodium nitrite to address the issues has led to production of meat with improved food safety, extended storage life. It has the E number E250, potassium nitrite is used in the same way. It is approved for usage in the EU, USA and Australia, Sodium nitrite is well known for its role in inhibiting the growth of Clostridium botulinum spores in refrigerated meats. The mechanism for this activity results from the inhibition of iron-sulfur clusters essential to energy metabolism of Clostridium botulinum, however, sodium nitrite has had varying degrees of effectiveness for controlling growth of other spoilage or disease causing microorganisms. Furthermore, the type of bacteria also affects sodium nitrites effectiveness and it is generally agreed upon that sodium nitrite is not considered effective for controlling gram-negative enteric pathogens such as Salmonella and Escherichia coli. The appearance and taste of meat is an important component of consumer acceptance, Sodium nitrite is responsible for the desirable red color of meat. Very little nitrite is needed to induce this change and it has been reported that as little as 2 to 14 parts per million is needed to induce this desirable color change. However, to extend the lifespan of this change, significantly higher levels are needed. The unique taste associated with cured meat is also affected by the addition of sodium nitrite, however, the mechanism underlying this change in taste is still not fully understood
9. Zinc borate – Zinc borate is an inorganic compound, a borate of zinc. It is a crystalline or amorphous powder insoluble in water. Its melting point is 980 °C, zinc borate is primarily used as a flame retardant in plastics and cellulose fibers, paper, rubbers and textiles. It is also used in paints, adhesives, and pigments, as a flame retardant, it can replace antimony oxide as a synergist in both halogen-based and halogen-free systems. It is an anti-dripping and char-promoting agent, and suppresses the afterglow, in electrical insulator plastics it suppresses arcing and tracking. In halogen-containing systems, zinc borate is used together with antimony trioxide and it catalyzes formation of char and creates a protective layer of glass. Zinc catalyzes the release of halogens by forming zinc halides and zinc oxyhalides, in halogen-free system, zinc borate can be used together with alumina trihydrate, magnesium hydroxide, red phosphorus, or ammonium polyphosphate. During burning the plastics, a porous borate ceramics is formed that protects the underlying layers, in presence of silica, borosilicate glass can be formed at plastic burning temperatures. Zinc borate is used in polyvinyl chloride, polyolefins, polyamides, epoxy resins, polyesters, thermoplastic elastomers, rubbers and it is also used in some intumescent systems. Zinc borate has synergistic effect with zinc phosphate or barium borate as a corrosion inhibitor pigment, zinc borate acts as a broad-spectrum fungicide in plastics and wood products. Zinc borate can be used as a flux in some ceramics, in electrical insulators it improves the ceramics properties. Nanopowder zinc borate can be used for the applications above, zinc borate in the Pesticide Properties DataBase
10. Zinc dithiophosphate – Zinc dialkyldithiophosphates are a family of coordination compounds developed in the 1940s that feature zinc bound to the anion of dithiophosphoric acid. These uncharged compounds are not salts and they are soluble in nonpolar solvents, and the longer chain derivatives easily dissolve in mineral and synthetic oils used as lubricants. They come under CAS number 68649-42-3, in aftermarket oil additives, the percentage of ZDDP ranges approximately between 2-15%. A mix of zinc dialkyldithiophosphates come under CAS number 84605-29-8, list of other examples with their CAS numbers is here. These species are produced in two steps, first phosphorus pentasulfide is treated with suitable alcohols to give the dithiophosphoric acid. A wide variety of alcohols can be employed, which allows the lipophilicity of the final product to be fine-tuned. The resulting dithiophosphate is then neutralized by adding zinc oxide, P2S5 +4 ROH →2 2PS2H + H2S2 2PS2H + ZnO → Zn2 + H2O In Zn2 and this monomeric compound also exists in equilibrium with dimers and oligomers caused by opening of the four-membered ZnS2P ring. Reaction with additional zinc oxide gives rise to the cluster, Zn4O6. These compounds are able to form coordination polymers. For example, zinc diethyldithiophosphate, Zn2, crystallizes as a solid consisting of linear chains. Roller camshafts/followers are more used to reduce camshaft lobe friction in modern engines. The same ZDDP compounds serve also as corrosion inhibitors and antioxidants and these compounds are widely used and correspondingly have numerous names, including ZDDP, ZnDTP, and ZDP
11. Zinc oxide – Zinc oxide is an inorganic compound with the formula ZnO. Although it occurs naturally as the mineral zincite, most zinc oxide is produced synthetically, ZnO is a wide-bandgap semiconductor of the II-VI semiconductor group. The native doping of the due to oxygen vacancies or zinc interstitials is n-type. This semiconductor has several properties, including good transparency, high electron mobility, wide bandgap. Pure ZnO is a powder, but in nature it occurs as the rare mineral zincite. Crystalline zinc oxide is thermochromic, changing from white to yellow when heated in air and this color change is caused by a small loss of oxygen to the environment at high temperatures to form the non-stoichiometric Zn1+xO, where at 800 °C, x =0.00007. Zinc oxide is an amphoteric oxide, ZnO forms cement-like products when mixed with a strong aqueous solution of zinc chloride and these are best described as zinc hydroxy chlorides. This cement was used in dentistry, ZnO also forms cement-like material when treated with phosphoric acid, related materials are used in dentistry. A major component of zinc phosphate cement produced by this reaction is hopeite, ZnO decomposes into zinc vapor and oxygen at around 1975 °C with a standard oxygen pressure. In a carbothermic reaction, heating with carbon converts the oxide into zinc vapor at a lower temperature. ZnO + C → Zn + CO Zinc oxide can react violently with aluminium and magnesium powders, with chlorinated rubber and linseed oil on heating causing fire and it reacts with hydrogen sulfide to give zinc sulfide. ZnO + H2S → ZnS + H2O Zinc oxide crystallizes in two forms, hexagonal wurtzite and cubic zincblende. The wurtzite structure is most stable at ambient conditions and thus most common, the zincblende form can be stabilized by growing ZnO on substrates with cubic lattice structure. In both cases, the zinc and oxide centers are tetrahedral, the most characteristic geometry for Zn, ZnO converts to the rocksalt motif at relatively high pressures about 10 GPa. Hexagonal and zincblende polymorphs have no inversion symmetry and this and other lattice symmetry properties result in piezoelectricity of the hexagonal and zincblende ZnO, and pyroelectricity of hexagonal ZnO. The hexagonal structure has a point group 6 mm or C6v, and the space group is P63mc or C6v4. The lattice constants are a =3.25 Å and c =5.2 Å, as in most group II-VI materials, the bonding in ZnO is largely ionic with the corresponding radii of 0.074 nm for Zn2+ and 0.140 nm for O2−. This property accounts for the formation of wurtzite rather than zinc blende structure
12. Zinc phosphate – Zinc phosphate is an inorganic chemical compound used as a corrosion resistant coating on metal surfaces either as part of an electroplating process or applied as a primer pigment. It has largely displaced toxic materials based on lead or chromium, zinc phosphate coats better on a crystalline structure than bare metal, so a seeding agent is often used as a pre-treatment. One common agent is sodium pyrophosphate, natural forms of zinc phosphate include minerals hopeite and parahopeite, Zn32·4H2O. A somewhat similar mineral is natural hydrous zinc phosphate called tarbuttite, both are known from oxidation zones of Zn ore beds and were formed through oxidation of sphalerite by the presence of phosphate-rich solutions. The anhydrous form has not yet been found naturally, zinc phosphate is formed from zinc phosphate cement and used in dentistry. Zinc phosphate dental cement is one of the oldest and widely used cements, zinc phosphate cement is used for cementation of inlays, crowns, bridges, and orthodontic appliances and occasionally as a temporary restoration. It is prepared by mixing zinc oxide and magnesium oxide powders with a liquid consisting principally of phosphoric acid, water and it is the standard cement to measure against. It has the longest track record of use in dentistry and it is still commonly used, however, resin-modified glass ionomer cements are more convenient and stronger when used in a dental setting