Sergey L. Sinebryukhov

Electrochemical impedance simulation of a metal oxide heterostructure/electrolyte interface: A review

The results of an analysis of the literature data obtained when investigating processes of charge transfer at interfaces of heterostructures formed by various methods, including the high-energy methods, are presented in this paper. The performed investigation of oxide layers at the titanium surface, with use made of impedance spectroscopy data made it possible to reveal the nature and influence of some processes and factors on the charge transfer mechanism realized at a metal oxide heterostructure/electrolyte interface. Simulating an oxide/electrolyte interface gives one a chance to identify, in a spectrum, the responses that characterize the behavior of porous and poreless layers, as well as the responses that are due to the space-charge region formed in the oxide material and to the corrosion and diffusion processes.

Composite Polymer Containing Coatings on the Surface of Metals and Alloys

It was shown that the Plasma Electrolytic Oxidation (PEO) treatment followed by coating the superdispersed polytetrafluoroethylene (SPTFE) Forum® on the developed mesoporous PEO-layer resulted in a composite coating on the surface of metals and alloys (e.g., titanium, nitinol, steel). The electrochemical properties including contact corrosion currents of the galvanic couples steel/titanium with composite coating were studied by means of electrochemical impedance spectroscopy and potentiodynamic polarization. In addition, mechanical properties were examined. It was ascertained that the combination of PEO-produced coating with SPTFE provided increased corrosion stability of metals and alloys making them suitable for implantation surgery.

Charge transfer at the antiscale composite layer-electrolyte interface

Properties of composite coatings based on oxide layers formed on a titanium surface using the plasmic electrolytic oxidation method and processed using Forum® superdispersed polytetrafluorinethylene were investigated. A combination of electrochemical impedance spectroscopy, differential thermal analysis, and thermal gravimetry methods allowed one to establish the change of the surface state as a result of heating that determines the charge transfer mechanism at the heterostructure-electrolyte phase interface and the difference in the thermodynamic stability of the temperature fractions of the employed polymer.

Functional coatings formed on the titanium and magnesium alloys as implant materials by plasma electrolytic oxidation technology: fundamental principles and synthesis conditions

Abstract Metallic implants have been successfully used in medicine for the past 60–70 years. Historically, implants were designed only as mechanical devices, whereas the biological aspects of their application were beyond the researchers’ interest. The improvement of living conditions and the increase of the average life span have changed the situation. The clinical requirements for medical implants rise up substantially. Presently, it seems impossible to imagine the use of metallic implants in the human body without preliminary surface modification to modulate the interaction between the surrounding biological environment and the implant. The review highlights the most recent advances in the field of functional coatings formed on implants by the plasma electrolytic oxidation technology. Special attention is dedicated to the principles of surface modification of the commercially pure titanium, titanium nickelide, and Mg-Mn-Ce magnesium alloy. The advantages and disadvantages of the method and the characteristics of these materials are discussed from this point of view. Some aspects of this review are aimed at corrosion protection of implants with application of polymer materials.

Hydrophobic properties of composite fluoropolymer coatings on titanium

The results of studies of the hydrophobicity of composite coatings on titanium formed using the method of plasma electrolytic oxidation (PEO) with further treatment by superdispersed polytetrafluoroethylene and its low-molecular fractions are presented. The chosen regimes of application of fluoropolymer materials of different fractional composition onto oxide coatings allow enhancing significantly hydrophobic surface properties (the contact angle reaches 131°).

Protective oxide coatings on Mg-Mn-Ce, Mg-Zn-Zr, Mg-Al-Zn-Mn, Mg-Zn-Zr-Y, and Mg-Zr-Nd magnesium-based alloys

Protective coatings are formed on different magnesium-based alloys (Mg-Mn-Ce, Mg-Zn-Zr, Mg-Al-Zn-Mn, Mg-Zn-Zr-Y, and Mg-Zr-Nd) by plasma electrolytic oxidation. Electrochemical and mechanical properties of the coatings are studied, as well as their chemical and phase compositions and structures. Analysis of the data obtained revealed the reasons for the differences in the corrosion and mechanical characteristics between plasma electrolytic layers formed on different magnesium alloys used in aviation and space engineering.

Composite coatings formed by plasma electrolytic oxidation

The prospects of using organic and inorganic nanosized materials are shown in the process of the formation of surface multifunctional composite protective layers obtained using plasma electrolytic oxidation on metals and alloys.

Magnetic properties of surface layers formed on titanium by plasma electrolytic oxidation

The magnetic properties of the coatings formed by plasma electrolytic oxidation on titanium and modified by nanoparticles of cobalt were studied. The coercitivity of the obtained magnetoactive layer were equal to 514 Oe at room temperature and to 1024 Oe at 2 K. The high coercitivity is the result of the nanosize effects of particles embedded in the coating. The structure of the nanoparticles, which consist of a Co ferromagnetic core and a CoO antiferromagnetic shell, determines the magnetic properties of the coatings on the whole.

Obtaining ZrO2 + CeOx + TiO2/Ti compositions by plasma-electrolytic oxidation of titanium and investigating their properties

Regularities of the effect produced by Ce2(SO4)3 salt introduced in an aqueous electrolyte containing Zr(SO4)2 on the plasma-electrolytic formation of oxide coatings on titanium, their composition, and structure are studied. ZrO2 + CeOx + TiO2 three-phase oxide coatings with a thickness about 10 μm are obtained. The coatings involve ZrO2 cubic phase. The ZrO2-to-TiO2 phase ratio in the coatings can be controlled. The zirconium content in the coatings reaches 20 at %, while that of cerium is 3–5 at %. The surface layer (∼3-nm thick) contains Ce3+ (∼30%) and Ce4+ (∼70%). Pores in the surface part of coatings have diameters around or smaller than 1 μm and are regularly arranged. The obtained systems have a certain catalytic activity with respect to the oxidation of CO to CO2 at temperatures above 400–450°C. The coatings are corrosion-resistant in chloride-containing environments. The thickness h of coatings depending on the charge Q supplied to the cell is described by the equation h = h0(Q/Q0)n, where n = 0.35 and h0 is the thickness of the coating formed at Q0 = 1 C/cm2.

Plasma Electrolytic Oxidation Coatings on Titanium Formed with Microsecond Current Pulses

The effects of shape and duration of the current pulses on the physico-chemical properties of the oxide layers on titanium formed by plasma electrolytic oxidation were examined. It was shown that in the investigated conditions transistor power source possess an advantage in comparison with thyristor one. Electrochemical properties of the heterooxide structures were examined by electrochemical impedance spectroscopy and potentiodynamic polarization methods.