Publications associées à Comparison of apparent activation energies for densification of alumina powders by pulsed electric current sintering (spark plasma sintering) and conventional sintering-toward applications for transparent polycrystalline alumina

Sinter-Resistant Nickel Catalyst for Lignin Hydrogenolysis Achieved by Liquid Phase Atomic Layer Deposition of Alumina

Jeremy Luterbacher, Farzaneh Talebkeikhah, Songlan Sun

Lignin hydrogenolysis is a key step in the sustainable production of renewable bio-based chemicals and fuels. Heterogeneous metal catalysts have led to high yields but they rapidly deactivate, notably due to nanoparticle sintering and carbonaceous deposit ...

2023

Liquid metal infiltration of silicon based alloys into porous carbonaceous materials Part-III: Experimental verification of conversion products and infiltration depth by infiltration of Si-Zr alloy into mixed SiC/ graphite preforms

Ludger Weber, Alberto Ortona, Manoj Kondibhau Naikade, Caroline Hain, Annapaola Parrilli

Porous carbonaceous preforms, made from graphite and silicon carbide (SiC) powders, with varying graphite powder mass fractions and particle sizes, were infiltrated at 1500 degrees C and 1700 degrees C by Si-8 at. pct Zr alloy to produce dense Si-Zr-SiC co ...

ELSEVIER SCI LTD2023

Kinetic processes in the high-temperature pressure-infiltration of Al into Al2O3

Andreas Mortensen, Ludger Weber, Gionata Schneider, Marta Fornabaio

We explore the influence (i) of the interaction between aluminium and alumina, and (ii) of sodium impurities present in Bayer alumina, on the pressure infiltration of alumina particle preforms with molten aluminium. At 1000°C or above, although the alumini ...

2020

Spark Plasma Sintering of Ceramics: From Modeling to Practice

Paul Bowen, Michael Stuer, Zhe Zhao

Summarizing the work of nearly a decade of research on spark plasma sintering (SPS), a review is given on the specificities and key factors to be considered in SPS of ceramic materials, based on the authors’ own research. Alumina is used primarily as a mod ...

2020

Engineering the ZrO2–Pd Interface for Selective CO2 Hydrogenation by Overcoating an Atomically Dispersed Pd Precatalyst

Mounir Driss Mensi, Jeremy Luterbacher, Oliver Kröcher, Florent Emmanuel Héroguel, Yuan-Peng Du, Alimohammad Bahmanpour, Luka Milosevic

Tailoring the interfacial sites between metals and metal oxides can be an essential tool in designing heterogeneous catalysts. These interfacial sites play a vital role in many renewable applications, for instance, catalytic CO2 reduction. Postsynthesis de ...

2020

Dynamic wetting in pressure-infiltration of ceramic particle preforms by molten metal

Gionata Schneider

This thesis investigates the interaction between mechanically induced flow of a liquid metal into a porous solid, and kinetic effects at the triple line. The approach is experimental and focuses on metal-ceramic systems for which the literature gives value ...

EPFL2019

Ni-Al2O3 nacre-like composites through hot-pressing of freeze-cast foams

A multi-step process is developed to create a nacre-like ceramic/metal composite. First, a slurry of Ni-coated alumina platelets and NiO nano-particles is directionally freeze-cast and the ice is sublimed, creating a foam with aligned lamellar walls contai ...

2019

Understanding snow bedform formation by adding sintering to a cellular automata model

Michael Lehning, Varun Sharma, Louise Braud

Cellular-automata-based modelling for simulating snow bedforms and snow deposition is introduced in this study. The well-known ReSCAL model, previously used for sand bedforms, is adapted for this purpose by implementing a simple sintering mechanism. The ef ...

Copernicus GmbH2019

Structural and microstructural studies on SiC-SiO2 ceramic composites

Ho-Yun Lee

In this study, SiC ceramic substrates were prepared with 99.5% silicon carbide powders which were came from waste silicon mud during the manufacturing process of solar cells. It is found that a SiO2 layer with 50 nm in thickness is present on the SiC surfa ...

2019

Synthesis and Sintering of ZnO Nanopowders

Paul Bowen, Michael Stuer, Zhe Zhao

Nanopowders are continuously under investigation as they open new perspectives in numerous fields. There are two main challenges to stimulating their development: sufficient low-cost, high throughput synthesis methods which lead to a production with well-d ...

Mdpi Ag2017

Probing the micromechanical strength of oxide ceramic composite reinforcements

Václav Pejchal

This work shows how one can probe the micromechanical strength of ceramic reinforcements used in metal matrix composites, which greatly influences the mechanical performance of the composite material yet has seldom been quantified with precision. More spec ...

EPFL2017

Grain boundary complexion and transparent polycrystalline alumina from an atomistic simulation perspective

Paul Bowen, Abhishek Tewari

Transparent alumina is often processed with sintering additives such as, Y, La, and Mg, in order to limit its grain growth at high sintering temperatures. Usually, these additives segregate to the grain boundaries due to their larger cationic size than Al ...

Elsevier2016

Self-Replenishing, Wear-Resistant and Anti-Sticking Surfaces Based on Liquid Impregnation of Microstructured Mesoporous α-AI₂O₃ [Alpha Alumina] Matrices

Sriharitha Rowthu

Fabrication of wear-resistant omniphobic surfaces is a persistent scientific challenge and essential for various applications such as in paint industries, fluid transport, antifouling, reduction of friction drag on ship hulls, and stain resistant textiles. ...

EPFL2016

Surface 3D Micro Free Forms: Multifunctional Microstructured Mesoporous alpha-Alumina by in Situ Slip Casting Using Excimer Laser Ablated Polycarbonate Molds

Paul Bowen, Patrik Willi Hoffmann, Sriharitha Rowthu

Ceramic surface microstructuring is a rapidly growing field with a variety of applications in tribology, wetting, biology, and so on. However, there are limitations to large-area microstructuring and fabrication of three-dimensional (3D) micro free forms. ...

Amer Chemical Soc2015

Toward Knowledge-Based Grain-Boundary Engineering of Transparent Alumina Combining Advanced TEM and Atomistic Modeling

Paul Bowen, Marco Cantoni, Michael Stuer, Cécile Hébert, Abhishek Tewari, Farhang Nabiei

Transition element dopants (e.g., Y, La) are commonly used as sintering aids in polycrystalline alumina ceramics, which segregate to the grain boundaries and control the grain-boundary mobility. However, due to the extremely thin (

Wiley-Blackwell2015

Properties of Spinel Protective Coatings Prepared Using Wet Powder Spraying for SOFC Interconnects

Jan Van Herle, Michele Bianco

A wet powder spraying (WPS) method was applied to prepare protective layers of manganese cobalt spinel oxide (MCO) on commercial stainless steels of solid oxide fuel cell (SOFC) interconnects. Densification of the MCO layer was dependent on the thermal tre ...

2015

Effect of interfacial interactions on the electromechanical response of poly(vinylidene fluoride-trifluoroethylene)/BaTiO3 composites and its time dependence after poling

Dragan Damjanovic, Yves Leterrier, Véronique Michaud, Sara Dalle Vacche

Solvent cast and compression molded composite films based on poly(vinylidene fluoride-trifluoroethylene), containing pristine and silylated BaTiO3 particles, were poled, and their electromechanical response (d(33)), their dielectric properties, and the cry ...

Elsevier2015

Electrochemical Performance of Nd1.95NiO4+delta Cathode supported Microtubular Solid Oxide Fuel Cells

Jan Van Herle

Nd1.95NiO4+delta (NNO) cathode supported microtubular cells were fabricated and characterized. This material presents superior oxygen transport properties in comparison with other commonly used cathode materials. The supporting tubes were fabricated by col ...

2015

Segregation of anion (Cl−) impurities at transparent polycrystalline α-alumina interfaces

Paul Bowen, Marco Cantoni, Cécile Hébert, Abhishek Tewari, Farhang Nabiei

Small amounts of anion impurities (e.g. Cl), which are incorporated during the synthesis of ceramic powders, can affect the properties and microstructure of the final sintered ceramic. The effect of anion impurities is a little studied and poorly understoo ...

Elsevier Sci Ltd2014

Fabrication and Test of High-Temperature Ceramic Transformer

Thomas Maeder, Peter Ryser, Conor Joseph Slater

This work describes the fabrication and test of a high temperature (+200°C) capable high frequency transformer. It was manufactured using Low Temperature Co-fired Ceramic (LTCC) technology, which allowed the complex multilayer structure of ceramic and meta ...

2014