Copper corrosion inhibition

Phosphonates can affect the corrosion of copper and usually are formulated in conjunction with TTA for copper corrosion inhibition. This may not be necessary if zinc is present in the formulation. 

Szocs E, Vastag GY, Shaban A, Konczos G, Kalman E. Investigation of copper corrosion inhibition by STM and EQCM techniques. J App ElectroChem 1999 29 1339. 

Three corrosion inhibitors for copper, 3-amino-l,2,4-triazole (ATA), benzotriazole (BTAH), and 1-hydroxybenzotiiazole (BTAOH), were investigated by corrosion experiments and atomistic computer simulations [75]. The trend of copper corrosion inhibition effectiveness of the three inhibitors in near-neutral chloride solution was determined experimentally as BTAH > ATA > BTAOH. An exhaustive analysis of the possible interactions between the molecules (in their neutral or deprotonated form) and the surface was done with PBE-D [75]. Physisorption, chemisorption, self-assembly as well as organome-tallic polymer formation attheCu(lll) surface were considered. The results are reported in Table 5.4. 

Table 9-12. Copper corrosion inhibition parameters in sodium chloride solution with or without inhibitors. ...

The most serious form of galvanic corrosion occurs in cooling systems that contain both copper and steel alloys. It results when dissolved copper plates onto a steel surface and induces rapid galvanic attack of the steel. The amount of dissolved copper required to produce this effect is small and the increased corrosion is difficult to inhibit once it occurs. A copper corrosion inhibitor is needed to prevent copper dissolution. 

Copper Corrosion Inhibitors. The most effective corrosion inhibitors for copper and its alloys are the aromatic triazoles, such as benzotriazole (BZT) and tolyltriazole (TTA). These compounds bond direcdy with cuprous oxide (CU2O) at the metal surface, forming a "chemisorbed" film. The plane of the triazole Hes parallel to the metal surface, thus each molecule covers a relatively large surface area. The exact mechanism of inhibition is unknown. Various studies indicate anodic inhibition, cathodic inhibition, or a combination of the two. Other studies indicate the formation of an insulating layer between the water surface and the metal surface. A recent study supports the idea of an electronic stabilization mechanism. The protective cuprous oxide layer is prevented from oxidizing to the nonprotective cupric oxide. This is an anodic mechanism. However, the triazole film exhibits some cathodic properties as well. 

Dissimilar metals in the same system Because of the specific action of many inhibitors towards particular metals, problems arise in systems containing more than one metal. In the majority of cases these problems can be overcome by the choice of a formulation incorporating inhibitors for the protection of each of the metals involved. With this procedure it is necessary not only to maintain an adequate concentration of each of the inhibitors but also to ensure that they are present in the correct proportion. This is because of two effects firstly, failure to inhibit the corrosion of one metal may intensify the attack on the other metal the best example of this is with aluminium and copper in the same system, and failure to inhibit copper corrosion — usually achieved with sodium mercaptobenzothiazole or benzotriazole—can lead to increased corrosion of the aluminium as a result of deposition of copper from copper ions in solution on to the aluminium surface. Secondly, an inhibitor of the corrosion of one metal may actually intensify the corrosion of another metal. Thus, benzoate is usually used to prevent the corrosion of soldered joints by nitrite inhibitor added to protect cast iron in the same system. A benzoate nitrite ratio of greater than 7 1 is necessary in these cases. 

Inhibitors form a film on the surface that blocks the dissolution of the substrate. Adsorption of an alkyl-thiol to the surface of the CU3AU alloy resulted in an inaeased surface tension of the gold film this is observed as an increase in the value of <., which depresses dissolution of copper. This behavior resembles inhibition of copper corrosion on a pure copper surface where benzotriazole increases the potential to start significant copper dissolution this was demonstrated by Cruickshank et using in situ AFM. However, when the critical potential for benzotriazole film... 

Inhibition of Copper Corrosion by Azole Compounds in Acidic Aqueous Solutions... 

Azole compounds, poly-N-vinylimidazole (PVI-1) and 2-undecylimidazole (UDI), are studied as alternative inhibitors to benzotriazole (BTA) for copper corrosion in aqueous systems using electrochemical techniques. It is shown that UDI, either as a cast film or dissolved in solution at concentrations as low as 7 X inhibits oxygen reduction on... 

Azole compounds such as benzotriazole, benzimidazole, indazole and imidazoles are efficient anti-corrosion agents for copper and copper-base alloys [1-10]. Many experimental techniques [11-15] have been used to study the corrosion inhibition mechanisms, however, the mechanisms are still not well understood. It is believed that the complex formation between copper and nitrogen atoms would inhibit oxygen adsorption on copper surface [16-20]. 

The ditetrazolium salts (309) have been patented for use in electrochromic electrodes which are used in display devices <89JAP01230026) and tetrazolium salts have also been developed for cell bioassays for neurotoxins active on voltage-sensitive sodium channels <93MI 417-03). Tests for inhibition of corrosion of zinc and brass carried out on 5-aminotetrazole showed it to be ineffective relative to other azoles <86MI 417-01). A number of tetrazoles including the 5-amino, 5-methyl, and 5-phenyl derivatives have been separately incorporated into surfactants used for corrosion inhibition with copper in water <9lMl4l7-07). Photopolymerizable resin compositions which are highly resistant... 

More than two-thirds of the naphthenic acids produced is used to make metal salts, with the largest volume being used for copper naphthenate consumed in the wood preservative industry. Oil field uses are primarily imidazolines for surfactant and corrosion inhibition. See also Petroleum. Besides the lubrication market for metals salts, the miscellaneous market is comprised of free acids used in concrete additives, motor oil lubricants, and asphalt-paving applications. See also Lubricant and Lubricating Agents. 

The EHD method with a RDE has been applied to the characterisation of porous layers of corrosion products formed on carbon steel [110], for the characterisation of salt films formed on copper [90, 111, 112] and iron [113], and for biofilms developed in natural seawater [114]. Corrosion inhibition films formed by an organic surfactant acting on the surface of pure iron have been characterised in this way, too [115]. An effect of a... 

Using the HSAB principle, one can rationalize the corrosion inhibition of iron and aluminum by phosphate in which iron phosphate and aluminum phosphate are produced. Ferric and Al3+ are hard acids, and they react with phosphate, a hard inhibitor and give corrosion protection. Corrosion inhibition of Cu2+ and Zn2+ by amines can be rationalized by the formation of amine complexes of Cu2+ and Zn2+, and this is in accord with the principle that Cu2+ and Zn2+ are borderline acids reacting with amines which belong to borderline inhibitors. Corrosion protection of copper (soft acid) by mercapto-benzothiazole (soft inhibitor) is also in keeping with the HSAB principle. 

As described earlier, the native copper oxide structures formed in the presence of an oxidizer under certain pH conditions can prevent the free dissolution of copper into copper ions. In addition to such oxide structures, there are at least three other types of layers that can accumulate on the oxidized copper surface to inhibit copper corrosion ... 

Thierry D, Leygraf C. Simultaneous raman spectroscopy and electrochemical studies of corrosion inhibiting molecules on copper. J Electrochem Soc 1985 132 1009. 

Fox PG, Lewis G, Boden PJ. Some chemical aspects of the corrosion inhibition of copper by benztriazole. Corrosion Sci 1979 19 457. 

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