Publications associées à Métal réfractaire

Enhanced radio-frequency performance of niobium films on copper substrates deposited by high power impulse magnetron sputtering

We present a study of radio frequency properties of niobium films deposited on copper by two different approaches based on High Power Impulse Magnetron Sputtering, namely with a DC voltage biased substrate and with bipolar target voltage. Such approaches e ...

2022

Liquid metal infiltration of silicon based alloys into porous carbonaceous materials. Part I: Modelling of channel filling and reaction phase formation

Ludger Weber, Alberto Ortona, Manoj Kondibhau Naikade

A relation for an adequate pore fraction needed to obtain residual Si and C free composites via reactive Si-X alloy infiltration is presented. The volume ratio of SiC and carbonaceous phase, the composition of the infiltrating liquid and the apparent densi ...

ELSEVIER SCI LTD2022

A concept for the extraction of the most refractory elements at CERN-ISOLDE as carbonyl complex ions

João Pedro Fernandes Pinto Ramos

We introduce a novel thick-target concept tailored to the extraction of refractory 4d and 5d transition metal radionuclides of molybdenum, technetium, ruthenium and tungsten for radioactive ion beam production. Despite the more than 60-year old history of ...

2022

Systematic investigations of uranium carbide composites oxidation from micro- to nano-scale: Application to waste disposal

Nhât-Tân Vuong

The production of radioisotope beams at the ISOLDE (Isotope Separator OnLine DEvice) facility at CERN is achieved by irradiating target materials (e.g. uranium carbides and metal foils) with protons. The materials are usually operated at temperatures above ...

EPFL2021

Nanoscale Mass-Spectrometry Imaging of Grain Boundaries in Perovskite Semiconductors

Mohammad Khaja Nazeeruddin, Iwan Zimmermann, Hiroyuki Kanda, Paul Gratia, Tom Theodorus Antonius Lummen

Incorporation of alkali metals such as Cs+, Rb+, and K+ into hybrid organic-inorganic halide lead perovskites (HOIPs) generally improves the optoelectronic properties of HOIPs. However, it is still uncertain how alkali metals interact and distribute within ...

2020

Activation of small molecules promoted by multimetallic complexes supported by redox active ligands

Davide Toniolo

The activation of small molecule is a topic of high current interest. A variety of homogeneous end heterogeneous catalysts have been studied to be able to promote chemical transformation of industrial relevance under mild condition and therefore decrease t ...

EPFL2020

Slowing the Kinetics of Alumina Sol-Gel Chemistry for Controlled Catalyst Overcoating and Improved Catalyst Stability and Selectivity

Jeremy Luterbacher, Yuan-Peng Du, Florent Emmanuel Héroguel

Catalyst overcoating is an emerging approach to engineer surface functionalities on supported metal catalyst and improve catalyst selectivity and durability. Alumina deposition on high surface area material by sol–gel chemistry is traditionally difficult t ...

2018

Evidence from Tm anomalies for non-CI refractory lithophile element proportions in terrestrial planets and achondrites

Philippe Gillet

Thulium is a heavy rare earth element (REE) whose geochemical behavior is intermediate between Er and Yb, and that is not expected to be decoupled from these elements during accretion of planetary bodies and geological processes. However, irregularities in ...

Pergamon-Elsevier Science Ltd2016

Titanium oxide aerogel composites

László Forró, Arnaud Magrez, Endre Horvath

The invention relates to titanium oxide aerogels, in particular to titanium oxide binary or ternary (e.g. titanium oxide-carbon) aerogel monoliths possessing ordered meso- and macroporosity. The porous scaffold can be made with or without addition of binde ...

2016

Flame-Made WO3/CeOx-TiO2 Catalysts for Selective Catalytic Reduction of NOx by NH3

Davide Ferri

Materials based on a combination of cerium-tungsten-titanium are potentially durable catalysts for selective catalytic NOx reduction using NH3 (NH3-SCR). Flame-spray synthesis is used here to produce WO3/CeOx-TiO2 nanoparticles, which are characterized wit ...

American Chemical Society2015

Thermal boundary conductance between refractory metal carbides and diamond

Christian Monachon, Ludger Weber

The thermal boundary conductance (TBC) between thin films of Cr, Mo, Nb and W and diamond substrates has been measured using time domain thermoreflectance before and after a high-vacuum heat treatment at 800 degrees C for 2 h. While no signs of carbide for ...

Elsevier2014

Low-cost industrially available molybdenum boride and carbide as “platinum-like” catalysts for the hydrogen evolution reaction in biphasic liquid systems

Hubert Girault, Xile Hu, Kurt Schenk, Heron Vrubel, Micheal Diarmaid Scanlon, Véronique Amstutz

Rarely reported low-cost molybdenum boride and carbide microparticles, both of which are available in abundant quantities due to their widespread use in industry, adsorb at aqueous acid–1,2-dichloroethane interfaces and efficiently catalyse the hydrogen ev ...

Royal Soc Chemistry2013

High Temperature Behavior of Nano-Structured Ceramic Composites Studied by Mechanical Spectroscopy

Mehdi Mazaheri

Silicon nitride based ceramics (SiAlONs); tetragonal polycrystalline zirconia (3Y‐TZP); alumina and their composites reinforced with different amount of multi‐ walled carbon‐nanotubes (CNTs) have been processed by Spark Plasma Sintering (SPS). High tempera ...

EPFL2013

First-principles model for phase stability, radiation defects and elastic properties Of W-Ta and W-V alloys

Nadine Baluc

Tungsten alloys are candidate materials for DEMO divertor applications because of their high melting point and low sputtering yield. We explore, using ab initio methods, the phase stability trend of W-Ta and W-V alloys. The available experimental phase dia ...

Elsevier Science Bv2013

Post-irradiation analysis of the tantalum container of an ISOLDE LBE target

CERN-ISOLDE operates a range of oxides, carbides, refractory metal foils and liquid metal targets for the production of radioactive ion beams. Following irradiation with a pulsed beam of 1 GeV and 1.4 GeV protons at temperatures reaching 600 degrees C, the ...

Elsevier Science Bv2012

Low-firing thick-film piezoresistive sensors for medical instruments

Peter Ryser, Thomas Maeder, Caroline Jacq

In this work, a low-firing thick-film materials system allowing fabrication of piezoresistive sensors on surgical alloys is presented in detail, with application to a force-sensing surgical instrument. The system comprises a series of individual thick-film ...

Elsevier2011

Phase stability, point defects, and elastic properties of W-V and W-Ta alloys

Nadine Baluc

The structure and phase stability of binary tungsten-vanadium and tungsten-tantalum alloys are investigated over a broad range of alloy compositions using ab initio and cluster expansion methods. The alloys are characterized by the negative enthalpy of mix ...

2011

Cathode-supported micro-tubular SOFCs based on Nd1.95NiO4 + δ: Fabrication and characterisation of dip-coated electrolyte layers

Jan Van Herle, Heinrich Hofmann, Paul Bowen, Josef Andreas Schuler, Ulrich Aschauer, Henning Lübbe

Fabrication conditions to obtain dense electrolyte double layers on a porous micro-tubular cathode substrate were investigated. Porous tubes of a nickelate material, Nd1.95NiO4 + δ, were fabricated by cold-isostatic pressing (CIP) and sintering. Thin ﬁlms ...

2009

Pulse plating of Ni-W alloys from model electrolytes

Dieter Landolt

Pulse plating of nickel-tungsten alloys has been studied from two citrate ammonia based model electrolytes containing either an excess of nickel or an excess of tungsten. The alloy composition and current efficiency were determined for pulse periods rangin ...

2008

Nanostructured tungsten-iron alloy prepared by electrodeposition

Nadine Baluc, Robin Schäublin

Tungsten-iron alloy was produced by electrodeposition. The electrodeposited alloy (15 at.% W) possesses a two-phase composite microstructure, containing a nanocrystalline phase of distorted BCC structure with a grain size between 50 to 150 nm and an amorph ...

2006