Electrodeposition and Corrosion Properties of Nickel–Graphene Oxide Composite Coatings

Nickel-based composite electrochemical coatings (CEC) modified with multilayer graphene oxide (GO) were obtained from a sulfate-chloride electrolyte in the reverse electrolysis mode. The microstructure of these CECs was investigated by X-ray phase analysis and scanning electron microscopy. The corrosion-electrochemical behavior of nickel–GO composite coatings in a 0.5 M solution of H2SO4was studied. Tests in a 3.5% NaCl solution showed that the inclusion of GO particles into the composition of electrolytic nickel deposits makes their corrosion rate 1.40–1.50 times less.

NITROGEN INFLUENCE ON THE CORROSION RESISTANCE OF THIN Ti-O-N FILMS DEPOSITED BY REACTIVE MAGNETRON SPUTTERING

The electrochemical and gravimetric methods were used to study the effect of nitrogen using in the reaction mixture during magnetron deposition on the Ti-O-N films corrosion-electrochemical behavior. Polarization studies of the films electrochemical dissolution in aque-ous solution of 3 % NaCl in a potentiostatic mode are presented. It was found that upon dis-solution of the films, passivation, activation, and passivation of the coating surface are ob-served, associated with the formation of oxide films and titanium chlorides on the sample sur-face. It has been proved that thin films obtained with a high nitrogen content exhibit higher corrosion resistance. In this work, the following corrosion parameters were calculated: mass, depth and current indicators.

The effect of argon and oxygen ion implantation on the physicochemical and corrosion-electrochemical properties of 14Cr17Ni2 chromium-nickel steel

The effect of argon and oxygen ion implantation both in separate and joint was carried out. Physical and chemical structure of the surface and corrosion-electrochemical behavior of 14Cr17Ni2 chromium-nickel steel was studied. Methods of potentiometry, atomic force microscopy, X-ray photoelectron spectroscopy, and microhardness measurement were used. It was found that the initial chromium-nickel steel exhibits high corrosion resistance in the medium of a borate buffer solution with the addition of a local corrosion initiator — potassium sulfate. However, steel was found to be susceptible to local (pitting) corrosion in this environment. It is shown that the implantation of argon and oxygen ions changes the nature of the corrosion-electrochemical behavior of chromium-nickel steel. Treatment with Ar+ ions enriched the sample surface with Cr atoms and reduces the overall corrosion losses of steel, but is characterized by the maximum value of local corrosion. Treatment with O+ ions provide optimal results in terms of reducing local and general corrosion. It was found that in this case, the sample surface is intensively oxidized to a depth of more than 20 nm, resulting in the formation of mixed oxides that are resistant to corrosion. There is a process similar to electropolishing of the sample surface due to partial dissolution of steel. Defects in the structure of the sample surface, on which pitting corrosion began, are “healed”. Joint treatment with Ar+ ions and O+ ions does not give noticeable advantages compared to separate implantation with these ions. Corrosion losses for samples treated only with O+ ions and Ar+ ions together with O+ ions did not exceed those for the original sample, although there are practically no passivation regions on the potentiodynamic curves. Microhardness of the samples after ion implantation coincides with the microhardness of the original sample. Result of ion implantation is no significant for change in the structural and phase structure of the surface layers of chromium-nickel steel. Ion implantation will not negatively affect the physical and mechanical properties of studied steel. The research shows that it is advisable to choose the type of implantable ions and the optimal process parameters depending on the steel grade and its application. For these purposes, the research methodology proposed in this article will be useful.

Influence of dipinaconborates on the corrosion resistance of ST3 steel in synthetic detergent solutions

Experimental data on the effect of lithium dipynaconborates (DPKBL), sodium (DPKBN) and potassium (DPKB) on the corrosion resistance of St3 steel in 3 % aqueous solutions of Labomid-203, MS-8 and Temp-100A synthetic detergents have been obtained. By measuring the stationary potentials of steel in solutions of synthetic detergents, the optimal concentration of dipinaconborates was revealed, which is 20 g/l, at which the highest corrosion resistance of steel is achieved. Studies of the corrosion-electrochemical behavior of St3 steel in 3 % aqueous solutions of Labomid-203, MS-8 and Temp-100A detergents showed that in the presence of dipinaconborates, the anode current density, at the same potentials, is much lower, and the passivation region is larger. than in CMC solutions. It was found that the corrosioninhibiting ability of dipinaconborates in CMC solutions increases in the series DPKBL < DPKBN < DPKBK, and potassium dipinaconborate has the greatest anticorrosive property. Dipinaconborates reduce the corrosion rate of steel at a washing solution temperature of 80 °C, the degree of protection is in the range from 71.4 to 90.6 %. And the braking coefficient is from 3.6 to 10.4. By analyzing the obtained experimental data, it was concluded that dipinaconborates increase the corrosion resistance of St3 steel and can be recommended as an anticorrosive additive to synthetic detergents.

Potentiodynamic Study of the Anodic Behavior of Zn5Al Alloy Doped with Manganese

The widespread use of zinc-aluminum alloys as protective coatings for structures, products, and structures requires studying the effect of various additives in such alloys on their corrosion resistance in various environments. In studying the anode behavior of alloys, potentiodynamic methods are widely used to select methods of protection and increase the stability of anode alloys under given operating conditions. The article presents the results of a potentiodynamic study of the corrosion-electrochemical behavior of Zn5Al alloys doped with manganese in various electrolytes. An increase in the manganese concentration within the studied concentrations leads to a shift in the standard potential and pitting potential to a positive region compared to the initial Zn5Al alloy, which indicates a decrease in the corrosion rate of the studied alloys by 2-2.5 times with respect to the base alloy. An increase in the concentration of chloride ions in the electrolyte leads to a decrease in the electrochemical potentials of corrosion and pitting formation of alloys, which indicates an increase in their anode stability. An increase in the anode stability of the protective coatings of alloys depends on the time spent in an aggressive environment: the longer the time, the lower the rate of anode dissolution.