Publications by Ludger Weber | EPFL Graph Search

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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 ...

We present dynamic measurement of drainage curves in two systems having relevance to metal matrix composite processing, namely SiC/Al and SiC/Al-12.2at%Si. Data show that liquid/solid chemical reactions that cause a lowering of the contact angle do indeed ...

Fe- or Mn-powders were mixed with the diamonds and the mixtures were heat treated under different gas atmospheres like hydrogen or argon gas and at varying temperatures in order to roughen the surface of the diamond particles. Subsequently the reaction lay ...

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 ...

The evolution of microstructural damage during tensile deformation of pure aluminium reinforced with 10 vol.% alumina short fibres is studied by monitoring the evolution of density and Young's modulus as a function of tensile strain. It is found that Young ...

The wetting of angular alumina particle preforms by Cu-Sn alloys is investigated by means of pressure infiltration experiments conducted at 1150 A degrees C, using a system enabling dynamic and precise measurements of the metal volume injected into the pre ...

The influence of sample processing parameters on the thermal boundary conductance (TBC) between aluminum and aluminum nitride has been investigated by transient thermoreflectance. An evaporated Al layer on the polished substrate yielded a TBC at ambient of ...

It is proposed that a critical combination of matrix strain hardening exponent and fibre volume fraction must be exceeded to confer attractive tensile ductility to short-fibre reinforced metal. © 2005 Acta Materialia Inc. Published by Elsevier Ltd. Al ...

Fibres fracture gradually during the fatigue cycling of continuous alumina fibre reinforced aluminium. The number of fibre breaks increases linearly with the logarithmic cycle number, depends on the maximum stress and the stress ratio, and agrees with publ ...

[100] and [111] oriented diamond substrates were treated using Ar:H and Ar:O plasma treatments, and 1:1 HNO3:H2SO4 heated at 200 ̊C. Subsequent to these treatments, an aluminum layer was either evaporated or sputte- red on the substrates. The Thermal Boundary Conductance (TBC) as well as the interfacial acoustical reflection coefficient between this layer and the diamond substrate was then measured using a Time Domain ThermoReflec- tance (TDTR) experiment. For the Ar:H plasma treated surfaces the [111] orie

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 ...

A heat sink that is particularly suitable for semiconductor components is made from a diamond-containing composite material. In addition to a diamond fraction amounting to 40-90% by volume, the composite material also contains 7 to 59% by volume copper or ...

The occurrence of new packages as well as the ongoing miniaturization in SMT make the evaluation of the reliability of solder joints an permanent task. Accelerated testing, especially passive thermal cycling, is a important tool to evaluate the lifetime of solder joints. However, tin-lead solder behaves viscoplastically even at ambient temperature because of its low melting point and therefore the temperatures of the tests performed as well as the temperature change rate are very important parameters for te

Diamond/metal composites with diamond contents between 57 and 72 vol% have been produced by gas pressure assisted liquid metal infiltration using Ag-3 wt% Si and Al-2 wt% Cu as matrix. The experimental data cover a range of Young's moduli from 300 to 425 G ...

Metal-diamond composites have been identified as promising materials for applications in which high thermal conductivity and low coefficient of thermal expansion is required, e.g. applications of thermal management. Besides the intrinsic properties of the metal matrix and the diamond the load and heat transfer at their interface is key for the composite performance. The present talk gives an overview of the current state of the art of metal diamond composites for thermal management with focus on ways of imp

Diamond reinforced metals with a diamond content of 55-60 vol.% were made by gas driven liquid metal infiltration. They were characterized with regard to their stiffness, strength and fracture toughness as a function of diamond particle size and matrix all ...

The influence of the thickness of a thin (1.5-30 nm) copper layer on the thermal boundary conductance (TBC) at the interface between gold and silicon, sapphire and diamond, respectively, was studied using Time Domain Thermoreflectance. Overall, a monotonic ...

The influence exerted by the shape of randomly oriented non-conducting inclusions on the electrical conductivity of a metal is investigated using the aluminum-sit icon eutectic alloy. By varying the time and temperature of heat treatment after solidification, the shape of the silicon inclusions is varied between plate-like and close-to-spherical. The influence of the geometry of the inclusions on the resistivity of the composite is separated from the influence of varying amounts of silicon in solid solution

Particle reinforced composites are produced by infiltrating ceramic particle beds with 99.99% Al. Resulting materials feature a relatively high volume fraction (40-55 vol. pet) of homogeneously distributed reinforcement. The evolution of damage during tensile straining of these composites is monitored using two indirect methods; namely by tracking changes in density and in Young's modulus. Identification and quantification of the active damage mechanisms is conducted on polished sections of failed tensile s

This work aims at experimentally assessing the effect of structural disorder and/or chemical interdiffusion on thermal boundary conductance (TBC) at metal/dielectric interfaces. To this end, the TBC of Au/Si and Ti/Si interfaces was measured by time domain ...

Ludger Weber

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

Direct measurement of drainage curves in infiltration of SiC particle preforms: influence of interfacial reactivity

Surface Modification of Diamonds in Diamond/Al-matrix Composites

Thermal boundary conductance between refractory metal carbides and diamond

Damage evolution in Saffil alumina short-fibre reinforced aluminium during tensile testing

Infiltration of tin bronze into alumina particle beds: influence of alloy chemistry on drainage curves

Influence of sample processing parameters on thermal boundary conductance value in an Al/AlN system

Ductility of Saffil(TM) short fibre reinforced metals

Damage accumulation during cyclic loading of a continuous alumina fibre reinforced aluminium composite

Effect of diamond surface orientation on the thermal boundary conductance between diamond and aluminum

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

Dissipateur thermique constitue d'un materiau composite diamant-cuivre renfermant du bore

Metallurgical considerations for accelerated testing of soft solder joints

Rigidity of diamond reinforced metals featuring high particle contents

Metal diamond composites: Challenges in interface design

Mechanical behaviour of diamond reinforced metals

Influence of the thickness of a nanometric copper interlayer on Au/dielectric thermal boundary conductance

On the influence of the shape of randomly oriented, nonconducting inclusions in a conducting matrix on the effective electrical conductivity

Quantification of microdamage phenomena during tensile straining of high volume fraction particle reinforced aluminum

Influence of interfacial structural disorder and/or chemical interdiffusion on thermal boundary conductance for Ti/Si and Au/Si couples