Coercive force of double layer ferromagnetic materials

Peculiarities of the coercive force (CF) measuring of inhomogeneous ferromagnetic materials, in particular layered ones, are considered. The concept of effective CF of layered ferromagnetic materials is introduced. The analysis of the magnetic fluxes distribution in a double layer ferro-magnetic material during its reversal magnetization by an attachable transducer with a U-shaped core made of soft magnetic material is carried out. An analytical expression of the effective CF for such class of materials for the case of the same layers’ thickness and linear approximation of their demagnetization curves is obtained. It was found that the effective CF of a double layer ferromagnetic material is determined not only by the CF of its individual layers, but also by the values of their residual induction. Experimental verification of the obtained results was performed on experimental samples, which were collected from steel 08kp (sample # 1) and steel St3 (sample # 2) plates. Each of the samples was a stack of 6 plates each measuring 87×50×1 mm. With tight compression of the plates and complete elimination of the gaps between them, these samples can be considered as single layer ferromagnetic structures with a thickness of 6 mm. To model a double layer ferromagnetic material with the same layer thickness, sample № 3 was used. Its the upper part consisted of the three steel 08kp plates and the lower part – of the three steel St3 plates. To measure the magnetic parameters of these samples the KRM-Ts-MA type magnetic analyzer was used. The device permit to measure the CF, residual induction and other parameters of the hysteresis loops of ferromagnetic materials in the closed magnetic circuit by attachable type transducers with U-shaped core. The transducer used with the magnetic analyzer during the experiments had poles with an area of 16×32 mm and the distance between the edges of the poles: inner – 32 mm, outer – 64 mm. It is shown that the discrepancy between the calculated value of the effective CF of the double layer ferromagnetic material (sample # 3) from steel 08kp and St3 according to the obtained expression and the measurement results is about 3%. This confirms the adequacy of the proposed model of reversal magnetization of double layer ferromagnetic material and the correctness of analytical calculations.

Research of operational features of heat accumulators using on motor transport

Preheating of the engine is often used to facilitate the start of the internal combustion engine in winter, which provides an opportunity not only to increase the comfort of starting, but also to reduce exhaust emissions, increase engine life. That is why the choice of optimal heat storage materials, which on the one hand would have sufficient heat efficiency and on the other hand would satisfy the operational requirements regarding corrosion activity, etc., is an urgent problem. In particular, the barium octohydrate used in our studies is corrosive, although it has a high heat of phase transition heat. The media investigated the media that are ordinary working fluids for heat transfer during heat accumulation: antifreeze, antifreeze, water; heat-accumulating materials – paraffins and octohydrates, and as investigated in relation to corrosion of material steel St3 was considered. The working temperature range was used in the work. It was found that the corrosion rate of 3 mm per year in antifreeze and antifreeze environments requires the choice of anti-corrosion coating or the search for new material that will react.

Analysis of adsorption of carbon steel corrosion inhibitor in model stratum waters by polylogarithmic isotherm

Using the methods of gravimetry, potentiodynamic polarization, and impedance spectroscopy, the protective effectiveness of the inhibitory composition INCORGAZ-111 with respect to hydrogen sulfide corrosion of carbon steel St3 in NACE and Samotlor oil field model stratum waters has been studied. Surface coverage is determined on the basis of the electric double layer capacity in presence of the inhibitor. Its adsorption is interpreted using the polylogarithmic isotherm with a big energy gradient of adsorption centers, that indicates linear energy heterogeneity of the surface. The constants of adsorption equilibrium, the energy gradient and the energy dispersion of adsorption centers as well as adsorption free energy were calculated.

Comparative evaluation of the hardness of alloyed coatings from fastening CuSn—CrxCy mixture har dened by plasma and laser

The article is devoted to a comparative assessment of the possibility of increasing the wear resistance of the surface layer for steel St3 during plasma and laser heating of the applied surface coating of a mixture of CuSn—CrxCy alloys. It is shown that the fusion of a thin layer of a preliminarily applied coating of a CuSn—CrxCy mixture with a wide range of particle sizes is more suitable for plasma than for laser processing. It has been found that plasma coatings have a higher hardness and a lower probability of defects as compared to laser coatings. The results obtained can be used in the development of new technological processes for hardening machine parts and tools.

INVESTIGATION OF SOME COMPOSITIONS OF THE «SOLING» SERIES AS CORROSION INHIBITORS FOR LOW-CARBON STEEL IN ACIDIC MEDIA

The inhibiting effect of some compositions of «Soling» series on low-carbon steel St3 in solutions of 5% and 15% HCl and 5% H2SO4 has been studied by the methods of polarization and gravimetric measurements. The protective action and the coefficient of inhibition of the corrosion process are calculated, the slopes of the Tafel sections in the cathode and anode regions of the polarization curves have been calculated. The influence of inhibitors on the kinetics of partial electrochemical reactions has been determined. The state of the surface of the samples has been estimated using micrographs. The high efficiency of inhibitors in acidic media has been shown.

Bactericidal properties of a combined corrosion inhibitor in the presence of SRB

The bactericidal properties of the combined inhibitor with respect to two types of Desulfovibrio desulfuricans and Desulfomicrobium sulfate-reducing bacteria were studied. The effect of the inhibitor on the number of bacterial cells and the formation of hydrogen sulfide in Postgate nutrient Postgate “B” was evaluated. It has been shown that the combined inhibitor exhibits a bacteriostatic effect on to sulphate-reducing bacteria. It was revealed that the degree of suppression of the number of microorganisms Desulfovibrio desulfuricans at a concentration of the combined inhibitor 100,0 mg/L is higher than Desulfomicrobium. In the latter case, to achieve this effect, 120,0 mg/L concentration of the combined inhibitor is required. The studied combination inhibitor causes the inhibition of hydrogen diffusion in steel St3 in the MI medium saturated with H2S and CO2 separately and together, and also contributes to preserving the ductile properties of the steel St3 after exposure to solutions compared to non-inhibited media.

New software for corrosion research based on IPC series potentiostats

The developed IPC-CorrMeter software is intended for studying corrosion of metals, alloys, and coatings and estimating the efficiency of anti-corrosion protection by emulating the operation of a “Corrosimeter” device in potentiostats of the IPC series that allows implementing well-known and reliable corrosion-electrochemical methods, such as linear polarization resistance, zero resistance amperometry, and potentiometry in the existing serial IPC potentiostats. The advantages of the new software include: a possibility of continuous automatic use of these methods in the study of corrosion processes, obtaining results almost in real time mode, high sensitivity and a wide adjustable range of measurements of the rates of general and pitting corrosion (from 1 nm to tens of mm per year), no absence of any restrictions regarding the RAM size of the device. Quantitative dependences of the general and pitting corrosion rate of steel St3 in water are obtained in the presence of the industrial СARTEС-28B corrosion inhibitor for hydraulic testing of mud pumps. They confirm the reliability, accuracy, high sensitivity, and validity of the IPC-CorrMeter software and equipment for researching metal corrosion and allow evaluating the efficiency of anti-corrosion protection agents, as well as the high efficiency of this inhibitor.

STUDY OF UNIVERSAL COMBINED INHIBITOR FOR OIL AND GAS INDUSTRY

Using the gravimetric method, the inhibitory efficiency of the combined inhibitor with respect to hydrogen sulfide and carbon dioxide corrosion of St3 steel in model-produced water MI was studied. Corrosion tests were carried out in 0.5 l sealed vessels on St3 samples of size 30×20×1. Gossypol resin + MARZA was used as a multifunctional combined inhibitor. Diesel fuel and kerosene were used as solvent. It has been established that the protective effect of using a multifunctional combined inhibitor in formation water with oil containing hydrogen sulphide and carbon dioxide using kerosene as a solvent ranges from 75 to 96 and for diesel as 80 to 100. The combined inhibitor allows to achieve in the MI medium containing hydrogen sulfide and carbon dioxide in the process of daily testing the corrosion rate of steel is about 0.04 g/ m2∙h only in a concentration of not less than 70 mg/l. However, with an increase in the duration of the test by an order of magnitude, a similar corrosion rate is observed already at an inhibitor concentration of 50 mg/l. The same is characteristic of carbon dioxide and hydrogen sulfide - carbon dioxide solutions. The bactericidal properties of the combined inhibitor with respect to two types of Desulfovibriodesulfuricans and Desulfomicrobium sulfate-reducing bacteria were studied. The effect of the inhibitor on the number of bacterial cells and the formation of hydrogen sulfide in Postgate nutrient medium “B” was evaluated. It has been shown that the combined inhibitor exhibits a bacteriostatic effect on to sulphate-reducing bacteria. It was revealed that the degree of suppression of the number of microorganisms Desulfovibriodesulfuricans at a concentration of the combined inhibitor 100.0 mg/l is higher than Desulfomicrobium. In the latter case, to achieve this effect, 120.0 mg/l concentration of the combined inhibitor is required. The studied combination inhibitor causes inhibition of hydrogen diffusion in steel St3 in the MI medium saturated with H2S and CO2 separately and together, and contributes to preserving the ductile properties of the steel St3 after exposure to solutions compared to non-inhibited media.

ОСОБЕННОСТИ КАТОДНЫХ И АНОДНЫХ РЕАКЦИЙ НА УГЛЕРОДИСТОЙ СТАЛИ В ЗАВИСИМОСТИ ОТ ГЛУБИНЫ ПОГРУЖЕНИЯ В НЕЙТРАЛЬНЫЙ РАСТВОР

The investigation of the depth immersion of the specimens on corrosion rate of steel St3 in 3 % NaCl solution. Simulation of atmospheric corrosion (humid and wet) was performed by immersing of a steel sample by the size of (50×10×2) mm in a neutral solution of 3% NaCl at different depths. By leading the lower boundary of the working surface of the sample to the level of the solution (about 0 mm), humid corrosion was simulated, submerged to a depth of 2 mm (up to the upper boundary), wet corrosion, and 10 mm from the upper boundary - the electrolyte volume. The developed method allowed to carry out electrochemical researches by the method of polarization curves. The polarization curves were measured in the potentiodynamic mode with the potential scanning rate of 5∙10-4 V/s .The working electrode was a sample of steel St3 by the size (10×50×2) mm. A work surface (10×2) mm was separated on the sample, the rest of the surface was isolated with a non-conductive varnish. The results of the investigation of the effect of depth immersion of samples into electrolyte solution on corrosion rate of St3 steel are presented. The conditions of “humid” and “wet” atmospheric corrosion of the metal were simulated by the immersion of samples on a depth from 0 to 10 mm into 3% sodium chloride solution. It was found, that on the base on determination of the rate of particular electrode reactions occurring on the electrode at various depths of its immersion into the solution, the corrosion rate of steel St3 was determined by the value of the limiting diffusion current.It was shown that the value of limiting current increases from 0.51 to 2 A/m2 with decreasing of the film thickness. It has been established that the cathodic process rate depends both on the concentration of oxygen in the layers of the solution, which are at different distances from the solution/air boundary, and on the speed of its diffusion to the metal surface. Because the method of polarization resistance allows to measure the currents smaller than the currents of oxygen reduction in thin films of the solution, it can be used to estimate the rate of atmospheric corrosion of steel. Based on simulation of humid and wet atmospheric corrosion the effect of immersion depth of the specimens on the cathodic reaction rate of steel St3 in 3 % NaCl solution was established. The cathodic current density (limit diffusion current) is raised from 0,51 to 2 A/m2 under decreasing of immersion depth. The suggested method of simulation of atmospheric corrosion may be used for electrochemical investigations in thin films of moisture of different thickness which are form on the metals and sensors surfaces. The possibility of application of polarization resistance method for atmospheric conditions was presented.