Search results for "Current density"
showing 10 items of 99 documents
High-pressure synthesis of CO and syngas from CO2 reduction using Ni-N-doped porous carbon electrocatalyst
2022
Abstract Electrochemical conversion of CO2 to CO or syngas (CO/H2 mixture) is considered one of the most promising approaches to valorise waste-CO2. To develop the process on industrial scale, it would be necessary to use selective and inexpensive electrodes and to obtain high productivities with low energy consumption. In this frame, Ni−NC catalysts are considered among the most interesting ones because of their relatively low cost, high faradaic efficiency in CO ( F E C O ), and high stability. However, up to now, quite low productivities were obtained as a result of low current densities achieved in aqueous electrolytes. In this work, we have evaluated the performances of a Ni−NC electro…
Mechanical properties and corrosion behaviour after scratch and tribological tests of electrodeposited Co-Mo/TiO2 nano-composite coatings
2019
International audience; The micro-mechanical (Young’s modulus and hardness) and tribological properties, as well as the scratch resistance of Co-Mo/TiO2 nano-composite coatings were investigated. The coating was found to be harder and stiffer than the substrate (pure cobalt). Low residual stresses were also derived from Stoney’s equation (type I stress). The corrosion behaviour after tribological and scratch tests was studied in Ringer’s solution. Dry sliding of the coating against an alumina ball at the load of 1 N or 2 N over the same distance had nearly no influence onthe anodic branch of the polarisation curves. By contrast, the current density in the cathodic branch (oxygen reduction r…
Magnetic field effect on electrodeposition of cobalt dendrites
2012
International audience; We are studying the effect of a magnetic field on cobalt dendrites grown by electrodeposition in thin cell. Several electrochemical parameters like pH, current density, initial concentration, are known to affect the crystalline structure of electrodeposited cobalt. Here we analyze, for two values of the pH, the effect of a high magnetic field (6 T) on the growth direction of the dendrites with respect to the crystalline axis of the structure.
Study of Gasdynamic Electron Cyclotron Resonance Plasma Vacuum Ultraviolet Emission to Optimize Negative Hydrogen Ion Production Efficiency
2019
Negative hydrogen ion sources are used as injectors into accelerators and drive the neutral beam heating in ITER. Certain processes in low-temperature hydrogen plasmas are accompanied by the emission of vacuum ultraviolet (VUV) emission. Studying the VUV radiation therefore provides volumetric rates of plasma-chemical processes and plasma parameters. In the past we have used gasdynamic ECR discharge for volumetric negative ion production and investigated the dependencies between the extracted H$^-$ current density and various ion source parameters. It was shown that it is possible to reach up to 80 mA/cm$^2$ of negative ion current density with a two electrode extraction. We report experime…
First experiments with gasdynamic ion source in CW mode.
2016
A new type of ECR ion source—a gasdynamic ECR ion source—has been recently developed at the Institute of Applied Physics. The main advantages of such device are extremely high ion beam current with a current density up to 600–700 emA/cm2 in combination with low emittance, i.e., normalized RMS emittance below 0.1 π mm mrad. Previous investigations were carried out in pulsed operation with 37.5 or 75 GHz gyrotron radiation with power up to 100 kW at SMIS 37 experimental facility. The present work demonstrates the first experience of operating the gasdynamic ECR ion source in CW mode. A test bench of SMIS 24 facility has been developed at IAP RAS. 24 GHz radiation of CW gyrotron was used for p…
Current-induced fingering instability in magnetic domain walls
2015
The shape instability of magnetic domain walls under current is investigated in a ferromagnetic (Ga,Mn)(As,P) film with perpendicular anisotropy. Domain wall motion is driven by the spin transfer torque mechanism. A current density gradient is found either to stabilize domains with walls perpendicular to current lines or to produce finger-like patterns, depending on the domain wall motion direction. The instability mechanism is shown to result from the non-adiabatic contribution of the spin transfer torque mechanism.
Influence of the microstructure and laser shock processing (LSP) on the corrosion behaviour of the AA2050-T8 aluminium alloy
2011
International audience; The corrosion behaviour of AA2050-T8 was studied after polishing and after laser shock processing (LSP) treatment using the electrochemical microcell technique and the SVET. After polishing, pitting at constituent particles and intergranular corrosion were observed. By contrast, no intergranular corrosion developed after LSP. Microcell measurements revealed that LSP increases the pitting potential. SVET measurements revealed that local anodic currents are systematically lower on LSP-treated surfaces than on polished ones. The current density on the LSP-treated surface remains constant around 50 μA cm−2 up to 123 min after immersion, while on the polished surface it r…
Corrosion Behaviour of Ti6Al4V and TiMo10Zr4 Alloys in the Ringer’s Solution: Effect of pH and Plastic Strain
2015
The corrosion behaviour of titanium alloys is not well understood – especially the role of the microstructure and plastic strain. In this paper, the influence of the microstructure and plastic strain on the corrosion resistance of TiMo10Zr4 and Ti6Al4V alloys was studied in the Ringer’s solution at 37 °C. Measurements were performed for different pH values and in aerated and de-aerated solutions using potentiodynamic polarization techniques. Results obtained on the two alloys were compared. It was shown that in the absence of plastic strain TiMo10Zr4 shows better corrosion resistance than Ti6Al4V (especially for pH = 8). By contrast, the current density in the passive range measured after 8…
Comparison of Cu-B Alloy and Stainless Steel as Electrode Material for Microbial Fuel Cell
2019
The microbial fuel cell (MFC) is a technical devices that electricity produces during wastewater treatment. One of the problems of MFCs is a low current density. Thus, it is necessary to search for new electrodes for MFC. The comparison of Cu-B alloy and stainless steel as catalyst for MFCs cathode is presented in this paper. The research included measurements of the concentration of COD, NH4+ and NO3− in three types of reactors: without aeration, with aeration and with using a MFC (with Cu-B and stainless steel cathode). It has been shown that effectiveness of MFC with Cu-B electrode is higher than effectiveness of MFC with stainless steel electrode.
Repassivation of the damage generated by cavitation on UNS N08031 in a LiBr solution by means of electrochemical techniques and Confocal Laser Scanni…
2010
Abstract The objective of this work is to study the influence of cavitation on the corrosion behaviour of Alloy 31, a highly-alloyed austenitic stainless steel (UNS N08031), in a LiBr heavy brine solution (992 g/L) at 25 °C. The presence of cavitation shifted the OCP value towards the active direction by 708 mVAg/AgCl, increased anodic current densities and passivation current density, ip, and reduced the pitting potential, Ep. Repassivation behaviour of Alloy 31 has been investigated by using potentiostatic tests at different potentials. The current density transient obtained after interrupting cavitation was used to obtain the repassivation index, n, provided by the slope of the log i(t) …