A multimaterial based on metallic copper and spinel oxide made by powder bed laser fusion: A new nanostructured material for inert anode dedicated to aluminum electrolysis

Coherent 3D parts of cermets, made of spinel ferrite and metallic copper, are prepared in a nitrogen atmosphere by powder bed additive manufacturing of a mixture of oxide and metallic powders. The cermets obtained are constituted by the association of blocks of about 500 μm, which create between them, a relatively large porosity (# 35%). Each block is subdivided into intimately nested zones that are either predominantly metallic or predominantly oxide type. In the metal parts, a dispersion of oxide crystals is observed, whose size varies from ten nanometers to a few micrometers. A similar distribution of metal particles in the oxide zones is also demonstrated. The chemical compositions of metallic and oxide phases are slightly different from those in the initial powders. Due to the high energy density of the laser, the melting temperature of the metal and oxides could be reached and therefore this could explain the chemical composition variations in the phases and the shape of oxide and metallic nanometric grains. The process used can therefore be described as powder bed fusion. These nanostructured cermets have been used as "inert" anodes for the electrolysis of aluminum in molten cryolite. Although penalized by a high porosity, 5 mm in diameter anodes allowed to carry out an electrolysis for 4 h. Since Spark Plasma Sintering can greatly reduce their porosity, while retaining their specific microstructure, the implementation of additive manufacturing for producing "inert" anodes is therefore of real interest

Il mercato del peer-to-peer lending nel mondo e le prospettive per l’Italia

Il mercato del peer-to-peer lending si è sviluppato sia in Europa che negli Stati Uniti e i modelli di business adottati dalle principali piattaforme presentano delle caratteristiche distintive dovute alla presenza di vincoli normativi differenti e a caratteristiche peculiari della domanda e dell’offerta. L’articolo presenta un’analisi dettagliata dei principali operatori del mercato considerando le caratteristiche delle piattaforme, dei clienti e dei contratti offerti

Electrochemical behavior of neodymium in molten chloride salts

International audienceThe discovery of NdFeB permanent magnets helps to perform technologies with reduced weight and gives them access to miniaturization. The industrial process of production of the Nd-Fe alloy by electrolysis used to manufacture of NdFeB magnets consists in reducing Nd$^{3+}$ ions dissolved in a LiF-NdF$_3$-N$_2$O$_3$ salt on iron cathode at 1050 DC. This route was chosen since the electroplating of neodymium at low temperature molten chloride leads to low recovery yields. This is usually attributed to the comproportionation reaction between the electrodeposited metal and its chloride salt (NdCl$_3$) leading to the formation of NdCl$_2$.In this work, the neodymium electrochemical behavior is reviewed in order to understand its reduction mechanism. Meal addition to LiCl-KCl-NdCl$_3$ melt is usually used to simulated comproportionation reaction in solution. Neodymium deposition yields are studied. Stability of Nd$^{2+}$ in two different solvent (LiCl-KCl and LiCl) is also discussed through electrodeposition tests on the gram scale

Il mercato del peer-to-peer lending nel mondo e le prospettive per l’Italia

Il mercato del peer-to-peer lending si è sviluppato sia in Europa che negli Stati Uniti e i modelli di business adottati dalle principali piattaforme presentano delle caratteristiche distintive dovute alla presenza di vincoli normativi differenti e a caratteristiche peculiari della domanda e dell’offerta. L’articolo presenta un’analisi dettagliata dei principali operatori del mercato considerando le caratteristiche delle piattaforme, dei clienti e dei contratti offerti

Etudes de voies potentielles pour le recyclage du zirconium des gaines en Zircaloy des combustibles uses

International audienc

The optimization of bimetallic electrodes’ sensitivity using copper nucleation on metallic substrates to detect nitrates in seawater

International audienceThe aim of this work is to highlight the beneficial impact of the nucleation mode study on controlling the electrodeposition of a metal on a substrate, in order to form high sensitivity bimetallic electrodes. Actually, optimizing the electrodeposition operating conditions allows generating the largest active surface, and so, increasing electrode sensitivity.For this purpose, the nucleation phenomena and the initial growth of copper nuclei on gold, platinum and stainless steel 316L electrodes were investigated using cyclic voltammetry (CV) and chronoamperometry in aqueous media. The experimental results were compared to theoretical models for the two possible nucleation modes: instantaneous and progressive.Chronoamperometric results showed that the electrodeposition process involves progressive nucleation for copper on the three substrates, which was confirmed by scanning electron microscopy (SEM).Optimal operating conditions were determined for the preparation of the highest active surface area. Subsequently, copper deposition runs were carried out on the three electrode substrates. The formed bimetallic electrodes were tested for their ability to detect low nitrate concentration in artificial seawater using square wave voltammetry (SWV)

electroreduction of oxides in molten fluoride salts

OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. Any correspondence concerning this service should be sent to the repository administrator: staff-oatao@inp-toulouse. b s t r a c t A new kind of electrolyte composed of molten fluorides has been evaluated in order to perform a feasibility study of the direct electroreduction reaction. The direct reduction of SnO 2 and Fe 3 O 4 was realised in LiF-NaF at 750 • C and in LiF-CaF 2 at 850 • C for TiO 2 and TiO. The electrochemical behaviour of these oxides was studied by linear sweep voltammetry: a current corresponding to the oxide reduction was evidenced for TiO 2 , SnO 2 and Fe 3 O 4 . After galvanostatic electrolyses, a complete conversion was obtained for all oxides, except TiO, and the structure of reduced Ti and Fe samples had a typical coral-like structure while dense drops of Sn were recovered (Sn is liquid at operating temperature). After TiO electrolysis, a thin external metallic titanium layer was detected, acting as a barrier for the oxide ion diffusion and no complete reduction can be achieved. This could be explained by a Pilling-Bedworth ratio around 1 for Ti/TiO