Engine coolants are mixtures of water and glycols (most commonly monoethylene glycol, MEG), formulated with corrosion inhibitors to protect the system materials. Nowadays, organic corrosion inhibitors are generally used in combination with inorganic corrosion inhibitors, such as silicates. To effectively formulate such engine coolant, it is of crucial importance to understand the behavior of silicate in a “semi-aqueous” environment. Silicate polycondensation has been thoroughly studied in aqueous solutions and the key factors influencing its aqueous chemistry are well defined (i.e. pH, temperature, concentration, etc.). In this paper the polycondensation chemistry of silicate in a wide range of MEG/water mixtures is thoroughly studied and the influence of several experimental parameters, such as working pH, condensation time and the MEG:water ratio, is investigated. The presence of MEG in MEG/water mixtures enhances silicate auto-condensation to form amorphous silica, at all pH values studied. Silicate condensation starts to occur within 10 minutes of pH adjustment and is faster with increasing MEG. The lowest levels of active silicate were observed in the pH region 8.0 to 8.5 (most common pH for engine coolants). The behavior of silicate was also studied in a generic coolant (which contains organic corrosion inhibitors in addition to MEG). In both cases condensation is severely enhanced. Temperature-driven amorphous silica particle dissolution was studied in selected MEG/water mixtures and it was found that it is negligible at ambient temperature regardless of the MEG:water ratio, whereas it is substantial at 90°C in pure water. Delineating silicate chemistry in coolant matrices will be valuable information for designing betterperforming formulations for engine coolant applications.

Using a complex of corrosion, electrochemical and physical methods, the structure and properties of protective layers of oleic acid (OlA) obtained by contact and chamber processing of magnesium were studied. It has been shown that the treatment of magnesium in a solution of OlK in isopropyl alcohol and in hot vapor of OlK leads to an increase in the corrosion resistance of the metal and inhibition of its anodic dissolution. Chamber processing (CT) is more effective compared to immersion. With both methods of processing magnesium, OlK forms protective films on the surface of approximately the same thickness, which, however, have a different structure. When magnesium is dipped into an OlK solution, rounded agglomerates are formed on it, almost merging with each other. In the case of CO, the surface films have a network structure. The protective effect of OLC is associated with the passivation of magnesium. However, during CO, passive films are characterized by high values of pitting potential and anti-pitting basis in chloride-containing electrolytes. Both options for inhibiting magnesium corrosion are characterized by a mixed blocking and activation mechanism. Moreover, in the case of CR, the activation mechanism dominates. 

Based on the random forest (RF) algorithm, two models have been obtained for predicting first-year corrosion losses (K₁) of carbon steel in an open atmosphere in various regions of the world. The first RF_general model was obtained using the combined databases of the international ISO CORRAG, MICAT, ECE/UN programs and tests in Russia and is designed to assess K₁ in various types of atmosphere in different regions of the world. The second RF_cont model allows you to predict K₁ in the continental regions of the world. The accuracy of K₁ predictions based on RF models and two dose-response functions was compared: the one presented in ISO 9223 standard and the new version developed by IPCE RAS for continental regions. It is shown that the reliability of both RF models is significantly better than the dose-response functions, with the exception of predictions of corrosion losses of steel in Russia with a cold climate. 

The corrosion of low-carbon steel in 2 M HCl was studied in the temperature range t = 25-95°C. For this environment, the possibility of creating mixed corrosion inhibitors (CIs) containing surfactants – catamin AB and cocamidopropylbetaine (CAPB) – has been considered. It has been shown that the compositions catamin AB + urotropine and CAPB + urotropine are promising for the creation of effective CIs steel in 2 M HCl. The optimal total content of mixtures of CIs in an aggressive environment is 5 mM. The molar ratio of surfactant and urotropine in mixtures of CIs is 1:9. The composition of 0,5 mM CAPB + 4,5 mM urotropine effectively slows down the corrosion of 08PS steel in 2 M HCl at t≤60°C, ensuring a steel corrosion rate of no higher than 3.9 g/(m²×h). At t = 60°C, steel corrosion slows down by 27 times. The composition of 0,5 mM catamin AB + 4,5 mM urotropine inhibits steel corrosion more strongly. A significant decrease in the corrosion rate of steel in its presence is observed at t≤80°C, when it does not exceed 6.9 g/(m²×h). The corrosion process at t = 80°C is slowed down 90 times. It is noted that replacing single-component CIs with two-component mixtures makes it possible to increase the efficiency of steel protection and reduce the consumption of the most expensive components used for their production.

Cooling systems (CO) are used in various industries. Often, they are a structure of different metals that are subject to contact corrosion. For this reason, aluminum alloys used in CO may lose their corrosion resistance. In this regard, it is important to conduct timely examination of CO. In this work, the water circulation cooling system of injection molding machines of the Swiss company Netstal Maschinen AG PetLine was studied. Determination of the causes, nature and rate of corrosion of CO through a visual examination, familiarization with the history of operation of CO, recommendations of service organizations, anti-corrosion measures and identified damage was carried out. The effectiveness of the inhibitor used in relation to the aluminum, copper and steel that makes up the CO parts was determined using linear polarization resistance and microscopy methods. It has been shown that the main reason for the increased corrosion rates of CO parts is the high content of oxygen and copper ions in the water used. In this case, a short-term increase in temperature in the system can lead to a significant acceleration of the corrosion rates of aluminum and copper, while the corrosion inhibitor used is primarily intended to reduce the corrosion rate of steel parts.

Aluminum oxide films are used as low refractive index layers in multilayer dielectric mirrors, which are expected to be used in ITER plasma diagnostic optical systems. In such mirrors, a film with a low refractive index is the outer layer. In addition to the normal operating modes of ITER, a number of emergency modes are assumed, one of which is the destruction of the water cooling system of the first wall, divertor or blanket. In this case, the vacuum chamber is filled with steam, the parameters of which depend on the location of the destruction and on the stage of operation of the reactor at which the accident occurs. The maximum steam parameters are set by a special system that limits the pressure to 150 kPa, and the maximum temperature of 250°C can be the case when an accident occurs during vacuum training of the chamber.

The work examines the interaction of steam with amorphous films of aluminum oxide deposited on glass of the K-9 grades by reactive magnetron sputtering. It has been shown that exposure of a film 300 nm thick at a temperature of 250°C and a steam pressure of 150 kPa for 2 hours is accompanied by intense hydroxylation of the film and the transformation of the entire oxide film into hydroxides. This leads to severe degradation of light transmission, which may cause a change in the optical properties of the dielectric mirror. As a next step, similar steam exposures are planned of the mirrors in which with a low refractive index layers will alternate with layers of oxides with a high refractive index, such as hafnium, tantalum, and zirconium oxides.

The effect of the octadecylamine:benzotriazole ratio on the protective effect of their mixture as a chamber inhibitor of steel corrosion has been studied by corrosion and electrochemical methods. It has been found that the anticorrosive aftereffect of the mixture depends on the ratio of the components. The inhibitor containing 75% of octadecylamine has the best protective properties. The mixture of octadecylamine and benzotriazole in the chamber treatment of steel is characterized by an antagonism of the protective action, but the inhibitor with the optimum composition is noticeably superior in efficiency to each component alone. The antagonism of the protective effect of octadecylamine and benzotriazole may be due to the acid-base interactions of these compounds accompanied by a decrease in the inhibitor vapor pressure. The protective action of the octadecylamine:benzotriazole mixture is caused by a stabilization of the passive state of steel that manifests itself as an increase in the pitting potential and/or anti-pitting base in chloride-containing electrolytes. The mixture studied acts by the "blocking-activation" mechanism with predominance of blocking effects.

Aluminum alloys with a high Mg content (above 4.5%) have high strength, but are more sensitive to corrosion than alloys with a low Mg content. To protect aluminum alloys, conversion coatings obtained by chemical oxidation can be used. It was previously shown that the alkaline chromate-free converting composition of IFKHANAL-3 makes it possible to obtain conversion coatings with high protective properties on the surface of the alloy. In this work, modifications of chromate-free inhibited conversion coatings IFKHANAL-3 were investigated in order to obtain coatings with high protective properties on aluminum alloys AMg5 and AMg6. The effectiveness of the coatings obtained was evaluated based on the results of corrosion and electrochemical tests. Modifying additives were used to enhance the protective effect.

The ability of the acid fuchsin (AF) dye to effectively inhibit the corrosion of copper and its alloy MNZh5-1 in a borate buffer with pH 7,4 containing 10 mmol/L NaCl, as well as in a more aggressive solution of 3,5% NaCl, was studied. Corrosion tests of copper in chloride-containing solutions showed that in a solution with 10 mmol/L sodium chloride, the introduction of 1 mmol/L AF provides a degree of protection Z = 97,7%, the introduction of 1,5 mmol/L AF completely protects copper from corrosion damage. In a solution with 3,5% sodium chloride, the degree of AF protection for the same concentrations is reduced to Z = 63,2%. Corrosion tests of the MNZh5-1 alloy in a 10 mmol/L NaCl solution with the addition of 1 mmol/L AF gives Z about 48%, which remains unchanged with a further increase in the concentration of acid fuchsin.

The paper presents data on the corrosion resistance of metal structural materials–copper grade M1, stainless steel 12H18N10T, carbon steel St3–in atmospheric conditions on the territory of the Staromainsky district of the Ulyanovsk region, obtained at the new corrosion station of the Institute of Physics and Chemistry of the Russian Academy of Sciences and MBOO Staromainskaya Secondary School No. 2 "Staraya Maina". Based on the data obtained, the atmospheric conditions were assigned a category of corrosion aggressiveness C2 according to GOST ISO 9223-2017.