A new method for the electrochemical polishing (ECP) of stainless steel to be used for stable functional osteosynthesis has been developed. Implants have been polished in solutions based on trinary system H 2 SO 4 -H 3 PO 4 -H 2 O with a stepwise decrease in current density and increase in orthophosphoric acid concentration. The optimal polishing conditions (current density, solution composition, temperature and duration) have been determined. The developed method improves the quality and the mechanical properties of the surface polished. K e y w o r d s: electrochemical polishing, stainless steels, implants, and functional osteosynthesis.
Thanks to the unique combination of physicochemical properties, niobium and its compounds are widely used in various fields of science and technology. The main areas of niobium’s applications are the production of superconductors, nuclear energy, chemical engineering, metallurgy, manufacture of optically active materials, thin-film lithium batteries, fuel cells. The aim of this work is to study the processes that take place on the niobium electrode in aqueous solutions of hydrofluoric acid, as well as to establish the composition of niobium compounds that are formed. The paper presents the results of studies the behavior of the niobium electrode in aqueous solutions 0.25 N. hydrofluoric acid. The kinetic parameters of the processes occurring at the phase boundary are determined. It was found that the anodic polarization of the niobium electrode is accompanied by the formation of a passive layer, the destruction of which is facilitated by increasing the polarization potential and fluorine anions, in the presence of which complex fluoroiobate anions [NbF7]2- and [NbOF5]2-are formed. Cathodic polarization of niobium is accompanied by the formation of hydrides on its surface, which causes an increase in the overvoltage of hydrogen evolution. The anodic polarization of the niobium electrode in a solution of hydrofluoric acid causes the formation on its surface of a passive layer, which is destroyed with increasing potential. In the Nbo–NbO2–0.25 –0.25 n HF system, [NbF7]2-anions are formed, as evidenced by bands in the region of 500 nm on the electron absorption spectra. The rate constants of [NbF7]2- and [NbOF5]2- formation are estimated at 3.78 • 10-3 s-1 and 5.18 • 10-3 s-1, respectively. The reduction of hydrogen at the niobium cathode from a solution of hydrofluoric acid is accompanied by the formation of hydrides, which causes an increase in the overvoltage of hydrogen evolution and high values of the angular coefficients of the Tafel dependence.
Thanks to the unique combination of physicochemical properties, metal hydrides (MH) are widely used in various fields of science and technology. High thermal, chemical and radiation resistance MH allows it to be used in nuclear industry as a material for nuclear reactors, chemical engineering, metallurgy for the production and refining of metals, for the production of devices operating at elevated temperatures and in adverse conditions. Unique properties MH are widely used in hydrogen energy as hydrogen storage, in rechargeable batteries. Analysis of literature data has shown that most studies are devoted to the practical use of the unique MH ability of reversibly absorbs a large amount of hydrogen. However, the electrochemical characteristics of the electrode processes of metal hydride systems were practically not investigated. The aim of this work is to study the processes that take place on the titanium electrode in sulfuric acid solutions, and the composition of titanium compounds that are formed. The paper presents the results of studies of the hydride formation reactions occurring on a polarized titanium cathode in aqueous solution 2 N sulfuric acid. The study was carried out using the following methods: the cyclic voltammetry and the method of x-ray phase analysis of the composition of the surface. It has been found that the reduction of hydrogen at the titanium cathode from a solution of sulfuric acid is accompanied by the formation of hydrides, which causes an increase in the overvoltage of hydrogen evolution and high values of the angular coefficients of the Tafel dependence. The kinetic parameters of this process have been calculated: the transfer coefficients α, theoretical and experimental angular coefficients btheor and bexp , exchange currents ie, the dependence of the hydrogen overvoltage from temperature. It has been found that exchange current density of hydrogen evolution reaction in this system is close by value to the current exchange of hydrogen evolution at the noble metals Pd, Pt, Rh, Ir and are (2,70∙÷0,8)∙10-3А·sm-2 in the temperature range 298 ÷ 343 K. The value of activation energy of 19,83 kJ mol-1 indicates the diffusion control of this process.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.