Thin Protective Coatings on Metals Formed by Organic Corrosion Inhibitors in Neutral Media

Abstract

Protection of metals in neutral media with pH 5.0–9.0 (in humid atmospheres and various aqueous solutions) can be achieved by formation of thin coatings (up to several tens of nm) on their surfaces due to adsorption and more complex chemical interactions of organic corrosion inhibitors (OCIs) with the metal to be protected. The review contains three sections. The first section deals with coatings formed in aqueous solutions, while the second one, with those formed in organic and water-organic solvents. Here we consider metal protection by coatings mainly formed by the best-known classes of OCI (carboxylates, organophosphates and phosphonates) and estimation of its efficiency. The third section discusses the peculiarities of protection of metals in the vapor-gas phase, i.e., by volatile OCIs, and a relatively new type of metal protection against atmospheric corrosion by the so-called chamber inhibitors. OCIs with relatively low volatility under normal conditions can be used as chamber OCIs. To obtain a protective coating on the surfaces of metal items, they are placed in a chamber inside which an increased concentration of vapors of a chamber OCI is maintained by increasing the temperature. This review mainly focuses on the protection of iron, steels, copper and zinc.

Superhydrophobic Anticorrosive Phosphonate–Siloxane Films Formed on Zinc with Different Surface Morphology

“…The results obtained are consistent with the mechanism of the formation of protective layers on metals by alkyl phosphonates in neutral aqueous media. It is based on the possibility of nucleophilic substitution of a hydroxyl with an organic anion on the metal surface [ 1 , 2 ]. This process in the presence of SDDP on an oxidized zinc surface can be expressed in a simplified form by the following reaction: mZn(OH) 2 + n[R-PO 3 ] 2− → Zn m [R-PO 3 ] n +2OH − where R is hydrocarbon radical.…”

“…The protection of metals from corrosion by thin films with a thickness not exceeding several tens of nanometers formed with organic compounds is a current direction in corrosion science and practice [ 1 ]. Modern trends in this area are aimed at finding ways to directly design such films, in order to impart multifunctional properties to metal surfaces, namely anticorrosive, antifouling, self-cleaning, and adhesive properties.…”

Formation of Composite Coatings on Galvanized Steel from Organosilane Solutions Using Electrophoresis and Sol–Gel Technology

“…The anticorrosive effectiveness of HCCs obtained by electrophoresis and ormosil technology with subsequent treatment with hydrophobizers (HomaCryl acrylic–styrene dispersion and ODPA alcohol solution) has been proven by the results of corrosion tests. The impregnation of such coatings makes it possible to achieve high hydrophobization of the surface, thereby significantly increasing their protective properties in an aggressive atmosphere [ 42 ]. The conducted research can be useful for various technologies for obtaining organic–inorganic HCCs for metal.…”

Development of Metallo (Calcium/Magnesium) Polyurethane Nanocomposites for Anti-Corrosive Applications

“…Materials science has long been involved in the study of the protection of metal from corrosion [ 8 ]. Among many other techniques to solve this purpose, the application of protective coating and utilization of corrosion inhibitors are considered to be the best as they are cost-effective and convenient [ 9 ]. Protective coatings work as a fundamental barrier between the metal and the harsh environment to inhibit the ingress of corrosive ions [ 10 ].…”