The task of estimating the probable corrosion rate of underground steel pipelines has long been facing engineers and scientists and is still relevant. This review examines the factors influencing the formation and development of corrosion defects of underground pipelines, and various methods for predicting corrosion of pipelines. Models of various types (deterministic, probabilistic and created using machine learning) are shown and the criteria of their applicability are analyzed.
This review article examines research of the protection of copper and some of its alloys from corrosion by organic corrosion inhibitors (CIs) of the triazole class, primarily over the past ten years. In contrast to numerous reviews devoted to the analysis of the corrosion-inhibiting properties of 1,2,3-benzotriazole (BTA) and its derivatives, it is devoted to another large group of CIs class triazoles, the parent of which is 1H-1,2,4-triazole (TA). Much attention in this article is given to the study of adsorption of the studied CIs from neutral aqueous solutions on the surface of copper. It was carried out in situ at a constant electrode potential using the highly sensitive method of reflective ellipsometry. This made it possible to obtain adsorption isotherms of TA and its derivatives and to calculate from them the free energy of adsorption of these compounds on copper.
The aim of this work was to prepare protective films of alkenyl phosphonic acid (APC) in self–assembled molecular layer (SAM) on different metals in order to improve the corrosion resistance of steals surfaces.
The influence of the alloy composition as well as the condition of layer formation and its post–treatment was in the focus of the work in order to prepare compact nanofilm that can control the metal corrosion in chloride ion environment. The influence of layer formation parameters on the layer compactness and on the corrosion resistance were characterized by water contact angle values, by atomic force microscopy (AFM) as well as by roughness parameters. In order to increase the compactness of the APC–SAM layer the nanofilms were heat treated at different temperatures and time intervals. The change in the layer characteristics caused by deposition temperature and by the post–treatments was demonstrated by wet contact angles and by AFM. The increased anticorrosion effect caused by the proper preparation conditions, by post–treatments as well as by the metal composition was characterized by the change in the roughness parameters as well as in the morphology visualized by AFM. The results showed that the increased anticorrosion activity of the compact nanolayers is due to blocking the active area on the metal surface by forming barrier between the aggressive environment and the metal surface.
The adsorption and protective properties of teraphthal, the sodium salt of 4.5-octacarboxyphthalocyanine, on the surface of the copper alloy MNZh5-1 in a neutral borate buffer solution were studied. Teraphthal suppresses active anodic dissolution of the MNZh5-1 alloy in 0.01 M chloride buffer pH 7.40. The protective effect increases at Сinh = 1.2 µmol/l from 0.18 V to 0.35 V at 25 µmol/l. The adsorption energy (-Δ𝐺0𝑎,𝑚𝑎𝑥) of teraphthal on the surface of the MNZh5-1 alloy at E = 0.0 V is 78.8 kJ/mol. This value indicates chemisorption of the inhibitor on the electrode surface, which occurs due to the oxygen atoms of carboxyl groups. The thickness of the adsorbed layer, determined by ellipsometry methods, is ≈ 0.3 nm, which indicates a flat arrangement of teraphthal on the surface.
A uniformly inhomogeneous roughness is formed on the surface of the AD31 aluminum alloy after a laser treatment. Further treatment of the alloy with ethanol solutions of octadecylphosphonic (ODPA) and stearic (SA) acids leads to superhydrophobization of the surface. The results of the kinetics of degradation of superhydrophobic (SHP) state in water and a neutral salt spray chamber indicate the high stability of ODPA films. The stability of SA films can be increased by a layer-by-layer forming with vinyltrimethoxysilane. The protective ability of the SHP coatings was estimated by polarization measurements and corrosion tests.
The adsorption, protective and passivating effect of sodium salts of succinic, itaconic and a blend of alkenylsuccinic acids (SKAP-25) on the oxidized surface of copper and copper–nickel alloy MNZh5-1 in neutral buffer and chloride solutions was studied. The adsorption of sodium succinate and itaconate is adequately described by the full Temkin isotherm equation with the value of the free energy of adsorption (-Δ𝐺0𝑎) on oxidized copper at E=0.0 V being 77.4 and 65.4 kJ/mol, respectively. The values of (-Δ𝐺0𝑎) for these corrosion inhibitors on the preoxidized MNZh5-1 alloy electrode are 89.3 and 58.3 kJ/mol, respectively. Such values of (-Δ𝐺0𝑎) suggest chemisorption interaction of these organic anions with the oxidized surface of copper and its alloy. Corrosion tests of copper and alloy MNZh5-1 in solutions for 7 days showed that a formulation of SKAP with the sodium salt of 2-mercaptobenzothiazole.
The process of scale formation for the regime of intensive heat exchange on heat exchange surfaces with polymer protective coatings has been studied. The possibilities of modifying the anti-scale properties of coatings with the help of active homogeneous and microcapsulated additives are considered. It is shown that microcapsulated additives based on oxyethylidenediphosphonic acid (OEDFC) can be used to reduce the rate of scale formation, and modifiers based on modified silicones can be used to reduce the adhesion of scale to the coating. Thus, active additives. used in adaptive polymer anticorrosive coatings, they can ensure the maintenance of not only anticorrosive, but other important operational properties of “smart” coatings.
The corrosion of reinforcement steel in concrete is a serious and widespread problem in construction. Inhibitors play an important role in protection against it. The Institute of Physical Chemistry and Electrochemistry of the Russian Academy of Sciences has developed an inhibitor against corrosion of reinforcement steel in concrete named IFKhAN–80. It is a non–toxic and non–flammable formulation based on raw materials available in Russia. Its functional properties have been studied in detail under laboratory and field conditions of moderate climate. IFKhAN–80 is widely used in practice, but there was no experience of its application in the tropics. The ability of IFKhAN–80 to provide contact protection of reinforcement of steel reinforcement under tropical conditions has been studied in this work by corrosion and electrochemical methods. The high efficiency of the inhibitor even for concretes with high chloride content was shown.
The corrosion of copper in freely aerated solutions of citric acid (C6H8O7) at 20 ± 2 °C was studied. The corrosion rate of copper in such solutions does not significantly depend on the duration of contact of copper with an aggressive environment (1–20 days) and the concentration of C6H8O7 (0,001–2 M) in it. The aggressiveness of C6H8O7 solutions towards copper increases when moving from static media to media stirred with a magnetic stirrer. Also, the aggressiveness of C6H8O7 solutions towards metallic copper is increased by the presence of a corrosion product in them – Cu(II) cations. This effect is especially noticeable when it comes into contact with a corrosive environment stirred with a magnetic stirrer. To protect copper in freely aerated C6H8O7 solutions, a triazole derivative, IFKhAN-92, is recommended. The effectiveness of this inhibitor does not significantly depend on the duration of contact of the metal with the aggressive environment, the content of C6H8O7 in it, and the hydrodynamic characteristics of the solution. An important property of the IFKhAN-92 inhibitor is that it retains its protective effect against metallic copper even in the case of accumulation of Cu(II) cations in a corrosive environment, which manifests itself not only in static but also in dynamic environments. The dependence of the copper corrosion rate on the intensity of mixing of the corrosive medium in freely aerated solutions of 2 M C6H8O7 and 2 M C6H8O7+0,05 M Cu(II), both in the absence and presence of a corrosion inhibitor, is formally described by an equation of the form k= a+b*n1/2, where a and b are empirical parameters, n is the rotation frequency of the magnetic stirrer. Additives IFKHAN-92 reduce parameters a and b of this equation.
