Solid State Phenomena Vol. 312

Abstract: The plasma electrolytic oxidation (PEO) process was used to form an oxide layer on an Al5754 aluminum alloy for subsequent application of organic coating. The effect of the oxidation time on the morphology and anticorrosion properties of PEO-coatings was investigated. The oxide layer possess low apparent porosity and provides high adhesion to the paint. The resulting composite coating (CC) is characterized by high barrier properties in chloride solution.

Abstract: The paper presents the results of a study of the protective properties of composite coatings obtained on AMg3 aluminum alloy by plasma electrolytic oxidation (PEO) and subsequent modification of formed oxide layer with superdispersed polytetrafluoroethylene (SPTFE) from a suspension based on isopropyl alcohol. The incorporation of fluoropolymer decreased the porosity of base PEO-coating more than one order of magnitude. Formed composite layers increased wearproof of the samples by more than two orders of magnitude in comparison with PEO-coating. Additionally, polymer-containing coatings has higher adhesion compared to substrate. Formed composite layers possess superhydrophobic properties: contact angle attains 155°.

Abstract: In the present paper, a composite containing mixed oxides of tin and lead has been synthesized by the method of pulsed high-voltage discharge. Material was characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis and transmission electron microscopy. The composite consists of SnO₂ and PbO particles with an average size of ~350 nm, and SnPb₂O₄ nanowhiskers with size of 100 nm in diameter and few microns in length. The electrochemical performance of nanocomposite as a potential anode of lithium-ion battery has been investigated by the cyclic voltammetry and galvanostatic charge/discharge test in the potential range of 3.0–0.005 V. The reversible capacity of 821 mA·h/g was realized after 5-fold cycling at a current density of 100 mA/g. It was established that further cycling of the material is accompanied by a dramatic capacity fade: only 13 % of the initial capacity was obtained already after 10 cycles. The observed degradation in performance of nanocomposite results from its inability to compensate large lithiation/delithiation-induced volume expansion.

Abstract: The paper considers approaches that can lead to the growth of micro-and nanocrystals on the surface of coatings formed on valve metals by plasma electrolytic oxidation (PEO). Among these approaches, there are the use of electrolytes-suspensions, the addition of organic compounds to the electrolytes, the thermal annealing of ‘PEO layer/metal’ composites, including impregnated ones.

Abstract: This article is concerned with the analysis of ordering the arrays of TiO₂ and Al₂O₃ nanotubes using the correlation-spectral methods. As the tools, the spatial Fourier spectrum and one-dimensional autocorrelation function of SEM-image have served. It was shown that the arrays of the aluminum oxide nanotubes can have a nearly ideal ordering on a small scale at the expense of two-stage anodizing. It this case, the degree of order depends also on the purity of initial aluminum and sample preparation method. The introduced characteristics can serve as the measures of the structure order-disorder sensitive to both type and degree of order as a whole and to configuration of structural elements themselves.

Abstract: The pseudopotential method and density functional theory with Hubbard correction were used to study changes in the atomic and electronic structure of yttrium orthoferrite (YFeO₃) during vacancy formation. Depending on the value of non-stoichiometry in YFeO_3−δ (δ = 0.0625 and 0.25), the energy gain of one of the two types of vacancy decreases from 0.3 to 0.1 eV. So it have been shown that high concentrations of oxygen vacancies make more insignificant the difference in the type of formed vacancies.

Abstract: Presented paper considers the formation of protective coatings on MA8 magnesium alloy by plasma-electrolytic oxidation (PEO). The influence of current densities formation on the structure, corrosion properties of PEO-coatings was studied. Electrochemical and scanning electron microscopy of the surface and cross-section of the samples were carried out. The effect of changing the formation current density on the functional parameters of coatings, such as corrosion resistance, thickness and porosity was investigated.

Abstract: In this research the results of the formation of composite materials based on magnesium for the needs of implant surgery are discussed. The synthesis of porous magnesium with the inclusion of hydroxyapatite particles was preformed by means of a powder metallurgical mechanochemical process. The resulting samples were impregnated with bioactive additives such as shilajit. To protect against premature corrosion, the samples were coated with plasma electrolytic oxidation (PEO).

Abstract: The way of protective coatings formation on MA8 magnesium alloy by plasma electrolytic oxidation (PEO) in the electrolyte containing TiO₂(B) nanoparticles has been developed. It is shown that the coatings, which contain nanoparticles, have a significant advantage in microhardenss and adhesive strength in comparison with the surface layers obtained without their use.