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showing 10 items of 1701 documents
Coated interconnects development for high temperature water vapour electrolysis: Study in anode atmospher
2013
International audience; High temperature water vapour electrolysis (HTE) is an efficient technology for hydrogen production. In this context, a commercial stainless steel, K41X (AISI 441), was chosen as interconnect. In a previous paper, the high temperature corrosion and the electrical conductivity were evaluated in both anode (O-2-H2O) and cathode (H-2-H2O) atmosphere at 800 degrees C. In O-2-H2O atmosphere, the formation of a thin chromia protective layer was observed. Nevertheless, the ASR parameter measured was higher than the maximum accepted value. These results, in addition with chromium evaporation measurements, proved that the K41X alloy is not suitable for HTE interconnect applic…
A new route to grow oxide nanostructures based on metal displacement deposition. Lanthanides oxy/hydroxides growth
2012
Abstract A metal displacement reaction has been used in order to cause precipitation of oxide nanostructures within pores of anodic alumina membrane (AAM) templates. Here, we focus on the displacement deposition of LnO/OH (Ln = La, Ce, Sm, Er) nanostructures using Zn as sacrificial anode, employing a specific cell arrangement where a galvanic couple was formed between zinc anode and the Au thin layer covering template pore bottom. Progress of displacement deposition reaction into template channels was monitored measuring the open circuit potential as well as pH changes of the electrolyte. A progressive de-activation of the anode surface was observed for long deposition times, caused by depo…
Abatement of 1,1,2,2-tetrachloroethane in water by reduction at silver cathode and oxidation at boron doped diamond anode in micro reactors
2012
The treatment of aqueous solutions of 1,1,2,2-tetrachloroethane was performed by anodic oxidation at boron doped diamond (BDD), cathodic reduction at silver and coupled processes. Experiments were performed in macro and micro reactors with an interelectrode distance lower than 100. μm. Drastically higher abatements of the chlorinated compound and current efficiencies were obtained in microdevices that, furthermore, allowed to perform the electrolyses with low cell voltages in the absence of supporting electrolyte. When reduction and oxidation processes were carried out simultaneously in the microreactor, a higher abatement of pollutants was obtained with the same amount of the passed charge…
Photoelectrochemical evidence of inhomogeneous composition at nm length scale of anodic films on valve metals alloys
2016
Abstract Anodic films of different thickness (∼30 nm and 70 nm) were grown by anodizing sputtering-deposited Ta-19at% Al to different formation voltages. N incorporation into the anodic films was inducing by performing the anodizing process in ammonium containing solutions. Layered anodic films were prepared by a double formation procedure with a first anodizing step in ammonium biborate solution and second anodizing step in borate buffer solution, or vice versa. Glow Discharge Optical Emission Spectroscopy was employed to show the distribution of N across the oxide. Photoelectrochemical measurements evidenced a red shift of the light absorption threshold due to N incorporation. A model was…
Chitosan-Coating Deposition via Galvanic Coupling
2019
A galvanic method to deposit chitosan coatings on stainless steel substrate is reported. Deposition of suitable coatings is desired to improve biocompatibility and corrosion resistance of metallic medical devices to be implanted in human body. In the present work, a thin hydrogel layer of chitosan was deposited on 304SS by a galvanic displacement reaction, which is advantageous first as it does not require external power supply. 304SS was immersed into an aqueous solution of chitosan/lactic acid and electrochemically coupled with magnesium acting as a sacrificial anode. SEM images showed the formation of a uniform layer of chitosan with a thickness controlled by deposition time. Corrosion t…
Chalcogenide Glasses Based on Germanium Disulfide for Second Harmonic Generation
2007
International audience; High second-order susceptibilities are created by thermal poling in bulk germanium disulfide based chalcogenide glasses. Experimental conditions of the poling treatment (temperature, voltage, time) were optimized for each glass composition. The second-order nonlinear signals were recorded by using the Maker fringes experiment and a second-order coefficient χ(2) up to 8 pm V-1 was measured in the Ge25Sb10S65 glass. This value is obtained using a simulation based on accurate knowledge of the thickness of the nonlinear layer. Two mechanisms are proposed to explain the creation of a nonlinear layer under the anode: the formation and the migration of charged defects towar…
Numerical modelling of the electrochemical behaviour of 316L stainless steel based upon static and dynamic experimental microcapillary-based techniqu…
2008
Microcapillary-based techniques allow the selection and interrogation of single metallurgical sites and are therefore becoming increasingly popular to investigate the electrochemical behaviour of metallic phases and non-metallic heterogeneities in alloys. This study has been carried out to assess the differences between current measurements made using a 'closed' microcapillary system (the electrochemical microcell technique) with current measurements derived from a flowing 'open' microcapillary droplet cell (the scanning droplet cell). The experimental results were compared with calculations derived from a model system adopting a finite element approach. The corrosion system consists of fou…
Assessment on the use of the amorphous semiconductor theory for the analysis of oxide films
2015
Abstract Although the theory of Schottky barrier in amorphous semiconductors is generally accepted, the limits of validity of such theory have not yet been explored. The classic semi-analytical solution is obtained under the constraint of constant electronic density of states (DOS) distribution in the mobility gap. In order to take into account the presence of a DOS variable in energy, a semi-empirical corrective power law was introduced in this paper. It is shown that the equations derived for thick films maintain their validity also in the case of thin films, provided that the space charge region width remains lower than 70% of the whole film thickness. A new expression based on the use o…
Trends of Organic Electrosynthesis by Using Boron-Doped Diamond Electrodes
2019
The electro-organic synthesis is currently experiencing a renaissance due to the tremendous contributions of various electrocatalytic materials as well as the use of electric current as an inexpensive and suitable reagent to drive the electrosynthetic transformations, avoiding conventional chemical oxidizers or reducing agents. Consequently, electrosynthesis has a significant technical impact, because these processes can be easily scaled up, benefiting from advantages such as versatility, environmental compatibility (possibility of recovering and recycling non-converted substrates), automation (switching on or off electric current), inherent safety and potential cost effectiveness among oth…
Thermogalvanic corrosion of Alloy 31 in different heavy brine LiBr solutions
2012
Thermogalvanic corrosion generated between two electrodes of Alloy 31, a highly-alloyed austenitic stainless steel (UNS N08031), has been investigated imposing different temperature gradients in three deaerated LiBr solutions, under open circuit conditions by using a zero-resistance ammeter (ZRA). Besides EIS spectra were acquired in order to explain the obtained results. On the whole, cold Alloy 31 electrodes were anodic to hot Alloy 31 electrodes, since an increase in temperature favoured the cathodic behaviour of the hot electrode. Thermogalvanic corrosion of Alloy 31 in the LiBr solutions studied was not severe, although it negatively affects the corrosion resistance of the cold anode. …