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10 results on '"Ignatenko, Oleg V."'

2. Influence of Cr Nanoparticles on Plasma Electrolytic Oxidation Coatings on AM50 Mg Alloy.

Author

Lv, Wenze, Lu, Xiaopeng, Chen, Qianqian, Ma, Jirui, Karpushenkov, Sergey A., Ignatenko, Oleg V., and Wang, Fuhui

Subjects
ELECTROLYTIC oxidation, PROTECTIVE coatings, ALLOYS, NANOPARTICLES, SURFACE coatings
Abstract

The addition of Cr nanoparticles to a plasma electrolytic oxidation (PEO) electrolyte offers the possibility of producing layers with a broader range of coating compositions and improved properties. In this study, the effects of nanoparticles and various voltages on coating formation, microscopic morphology, and phase composition were investigated with in situ incorporation of Cr nanoparticles into PEO-coated Mg alloy. The results show that the corrosion performance of the coating was significantly improved when the final voltage was set to 460 V and the concentration of Cr nanoparticles was 1 g/L. Compared to the particle-free coating, the corrosion current density of the coating with the addition of 1 g/L Cr nanoparticles was reduced by two orders of magnitude. The impedance at the low frequency (0.01 Hz) increased by more than one order of magnitude after one hour of immersion, indicating a considerable improvement in corrosion resistance. Due to the high temperature during the coating-formation process, the Cr nanoparticles were oxidized, resulting in the formation of Cr2O3. The existence of Cr2O3 slightly increased the growth rate of the coating and sealed the open pores of the coating. [ABSTRACT FROM AUTHOR]

Published
2023
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6. High-pressure zinc oxysulphide phases in the ZnO-ZnS system

Author

Salak, Andrei N., Ignatenko, Oleg V., Zhaludkevich, Aliaksandr L., Lisenkov, Aleksey D., Starykevich, Maksim, Zheludkevich, Mikhail L., and Ferreira, Mario G. S.

Subjects
DIFFRACTION, DEPOSITION, FILMS, RICH, PARAMETERS
Abstract

Wurtzite-zincblende mixture, ZnO-ZnS (1:1wt.%), was thermally treated at 5GPa in order to explore a possible mutual solubility of the end members and formation of zinc oxysulphide phases under high pressure. The data on phase content, crystal structure, and microstructure from the X-ray diffraction and the scanning electron microscopy studies of the obtained compacts (ceramics) were compared and analyzed. It was found that as temperature is increased, the following processes occur in the ZnO-ZnS mixture under pressure: release of the mechanical stresses (between about 300 and 700 degrees C), recrystallization of the initial wurtzite and zincblende phases (700-900 degrees C), reaction between the end members (above approximate to 900 degrees C) that results in formation of mixed oxysulphides based on ZnO and ZnS, respectively, with the mutual solubility rate of about 8mol.%.

Published
2015

7. High-pressure induced phase formation in the CuGaS2-CuGaO2 chalcopyrite-delafossite system

Author

Salak, Andrei N., Zhaludkevich, Aleksandr L., Ignatenko, Oleg V., Lisenkov, Aleksey D., Yaremchenko, Aleksey A., Zheludkevich, Mikhail L., and Ferreira, Mario G. S.

Subjects
SOLAR-CELLS, DIFFRACTION
Abstract

Phase formation under high pressure int he chalcopyrite-delafossite system has been studied at 5 GPa and 500-1000 degrees C. The parent chalcopyrite composition used in this study was slightly Cu-deficient, corresponding to the chemical formula (Cu,Ga)(0.905)GaS2. It was revealed that under high-pressure and high-temperature conditions, a mixture of the parent phases partly decomposes to form Cu2S and Ga2O3. The defect chalcopyrite (Cu,Ga)(0.905)GaS2 splits into a near-stoichiometric CuGaS2 and Cu-deficient subic (sphalerite-like) phase of the (Cu,Ga)(0.8)S composition. Such a phenomenon has been considered in terms of characteristic features of chalcopyrite and sphalerite crystal structures. Delafossite CuGaO2 at 5 GPa and 1000 degrees C was found to recrystallize entirely, which results in the disappearance of the stacking faults in its layered structure. [GRAPHICS] (C) 2014 WILEY-VCH Verlag GmbH \& Co. KGaA, Weinheim

Published
2014

10. High-pressure induced phase formation in the CuGaS2-CuGaO2 chalcopyrite-delafossite system.

Author

Salak, Andrei N., Zhaludkevich, Aleksandr L., Ignatenko, Oleg V., Lisenkov, Aleksey D., Yaremchenko, Aleksey A., Zheludkevich, Mikhail L., and Ferreira, Mário G. S.

Subjects
HIGH-pressure solid-state phase transformations, CHALCOPYRITE crystals, CHEMICAL formulas, STOICHIOMETRIC combustion, SPHALERITE
Abstract

Phase formation under high pressure in the chalcopyrite-delafossite system has been studied at 5 GPa and 500-1000 °C. The parent chalcopyrite composition used in this study was slightly Cu-deficient, corresponding to the chemical formula (Cu,Ga)0.905GaS2. It was revealed that under high-pressure and high-temperature conditions, a mixture of the parent phases partly decomposes to form Cu2S and Ga2O3. The defect chalcopyrite (Cu,Ga)0.905GaS2 splits into a near-stoichiometric CuGaS2 and a Cu-deficient cubic (sphalerite-like) phase of the (Cu,Ga)0.8S composition. Such a phenomenon has been considered in terms of characteristic features of chalcopyrite and sphalerite crystal structures. Delafossite CuGaO2 at 5 GPa and 1000 °C was found to recrystallize entirely, which results in the disappearance of the stacking faults in its layered structure. [ABSTRACT FROM AUTHOR]

Published
2014
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