N. N. Andreev

On the Prediction of the Vapor's Pressure of Salt-Type Volatile Inhibitors

The possibility of calculating the volatility of corrosion inhibitors of the salt type is analyzed. It is found that organic salts of the onium type sublimate in accordance with the dissociative mechanism; hence, the saturated vapor pressure can be estimated from the constants of ionization of the acid and base the salt is composed of, their volatility and solubility, and the solubility of the salt itself.

Protection of Low-Carbon Steel from Carbon Dioxide Corrosion with Volatile Inhibitors. I. Liquid Phase

It was shown that many of the known basic inhibitors of atmospheric and hydrogen sulfide corrosion (D-4-3, N,N-diethylamino-2-methylbutan-3-one, and N,N-diethylaminoethanol) fail in CO2-containing electrolytes. Carbon dioxide corrosion in solution can be suppressed only in the presence of more hydrophobic octylamine and its higher homolog, namely, amine A. The new highly passivating inhibitors IFKhAN-72 and IFKhAN-74 are even more effective. IFKhAN-72 is superior to amine A (the best amine-based inhibitor among those studied) in protection effect and suppresses CO2 corrosion of steel over a wide temperature range by substantially retarding both electrode reactions. Because of its high penetrating ability, IFKhAN-72 can protect steel already covered with corrosion products. In addition, this inhibitor has a prolonged aftereffect.

Volatile inhibitors of atmospheric corrosion. IV. Evolution of vapor-phase protection in the light of patent literature

The review analyzes the patent literature dealing with metal protection by volatile corrosion inhibitors (VCIs) and materials based thereon. It has been found inhibitors of atmospheric corrosion with vapor pressure above 10 –5 mmHg can be used as VCIs, including nitrogen-containing bases of various nature, salts of nitrogen-containing bases with some inorganic or organic acids, organic nitro compounds, esters of organic and inorganic acids, heterocyclic nitrogen-containing compounds, etc. Vapor-phase metal protection is also performed using non-volatile compounds and formulations that can release compounds of the above types upon hydrolysis. VCIs for temporary protection can be used in the form of active compounds, solutions, packaging materials, porous emitters, inhibited air, or in special forms intended for the protection of specific product types. VCIs can be used for permanent protection of metal articles within polymer coatings (paints) and working liquids (hydraulic, cooling liquids, etc.).

Steel Corrosion Inhibition by Benzoic Acid Salts in Calcium Hydroxide Solutions

The influence of salts of substituted benzoic acids on steel behavior in chloride-containing solutions Ca(OH)2 was studied. It was shown that the studied compounds inhibit local metal depassivation, elevating its potential and extending its induction period. The efficiency of inhibiting protection decreases when both hydrophilic and hydrophobic substituents are introduced in the aromatic nucleus of benzoic acid. The possible mechanism of the influence of substituent nature on protective properties of the studied compounds was considered.

On Corrosion Protection of Steel with Solutions of Volatile Inhibitors

A mathematical model describing the inhibition of steel corrosion above the aqueous solutions of volatile amines was advanced. The influence of their structures on the effectiveness of metal protection was analyzed. Theoretical conclusions were compared with experimental data.

Depositing nanolayers of volatile organic compounds on metals for higher resistance to atmospheric corrosion

Atmospheric corrosion stability of metals can be achieved by coating their surfaces with superthin nanoscale layers. The scientific principles of inhibiting metal corrosion have been under development for many years, but a new direction of progress has emerged recently. The main achievement of research in this new direction is the possibility of covering metals in nanoscale films that, despite their extreme thinness, ensure high corrosion resistance of the metals under various atmospheric conditions. To this end, methods are suggested for producing such coatings from volatile organic compounds that can adsorb on metal surfaces from the gaseous phase. Increasing the irreversibility of adsorption of volatile corrosion inhibitors is necessary to strengthen the protective effect of the nanolayers they form on the surface. Nanolayer-coating protection has a number of fundamental advantages, including retention of article dimensions, a lack of a need for special utilization and degreasing methods, and affordability.

On the use of surfactants in the production of migrating corrosion inhibitors

The effect of surfactants on the ability of an inhibitor to penetrate cast stone and protect the reinforcing steel is studied. With accelerated methods, the effectiveness of IFKhAN-80, IFKhAN-80M, MCI 2020, NaNO2, NaNO2 + “A”, and “A” surfactants as migrating inhibitors is estimated. An IFKhAN-80M composite is found to provide the effective protection of steel under conditions simulating the effect of migrating inhibitors.

Volatile inhibitor of carbon dioxide corrosion of steel

Corrosion and electrochemical methods were used to compare the protective properties of cyclohexalamine and a new inhibitor, IFKhAN-70, under conditions simulating carbon dioxide corosion of industrial pipeline steel. The inhibiting properties of the latter inhibitor were found to be markedly higher. IFKhAN-70 can passivate steel; it is effective in the presence of corrosion products on the surface and displays an anti-corrosion aftereffect.

Environmental testing of the efficiency of IFKhAN-80, an inhibitor for corrosion protection of steel reinforcement in concrete

Environmental tests of the efficiency of IFKhAN-80, a corrosion inhibitor for steel reinforcement in concrete, have been carried out. It has been found that the electrochemical criteria for the estimation of the corrosion behavior of steel reinforcement in concrete recommended by GOST (RF State Standard) 31383-2008 are not informative under the test conditions used. In view of this, the effect of IFKhAN-80 on the kinetics of corrosion spot growth on steel surface has been analyzed. In the absence of an inhibitor, corrosion of reinforcement steel already occurs in the course of hardening of chloride-containing concrete. Once hardening is completed, the growth rate of corrosion spots decreases abruptly. The area of corroded surface remains unchanged for 6 months, then the growth of corrosion spots on the metal surface resumes. Addition of IFKhA N-80 with tempering water in amounts recommended by the developers slows down corrosion in the course of concrete hardening and during exposure under natural conditions. Application of IFKhAN80 onto the surface of concrete samples in amounts recommended by the developers can arrest the growth of corrosion spots for a long time.

Why we reject papers with calculations of inhibitor adsorption based on data on protective effects

We have been issuing our journal for almost three years. Now it seems a right time to summarize some results. They are positive in general, but with some reservations. The Journal has a fair number of readers. It has increased to 200–250 persons per month. It is a very good result for a specialized scientific journal. Still, the circle of readers continues to grow. The number of contributors is also increasing. During the three years that the journal exists, we have published over 70 papers dealing with various theoretical and practical aspects of inhibitory protection of metals. However, the number of publications might have been about 15% larger. Some manuscripts have been rejected by our reviewers. Let us analyze them in more detail. In most cases, manuscripts are rejected for the same reason: they contain calculations of metal surface coverage by an inhibitor based on data on inhibitor protective effects (Z). Why should this not be done without a special justification or at least assumptions? The answers to this questions have been given more than half a century ago and unfortunately have been forgotten by many researchers. We feel it appropriate to remind the readers about some concepts of the theory of inhibitor action. In the manuscripts that we had to reject, the values of surface coverage by an inhibitor () were calculated from so-called kinetic data, i.e., in essence, they were identified with the degrees of protection: