Publications by Ludger Weber | EPFL Graph Search

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We present here a study of the mechanical behavior of cellular Zn and Zn1.5Mg with densities between 11.9 and 24.5%, produced by replication processing using NaCl as a spaceholder. Cellular Zn and Zn1.5Mg deform homogeneously during quasi-static compressio ...

The thermal boundary conductance (TBC) of metal/dielectric couples was measured for a large variety of metals on silicon, sapphire, and diamond using time domain thermoreflectance and compared to data previously obtained on diamond. In the case of silicon, ...

Different predictive models-the Maxwell mean field approach, the differential effective medium scheme, the 2- and 3-phase self-consistent, and 3-point model-for the electrical conductivity of two-phase materials are assessed based on electrical conductivity measurements of metal matrix composites with non-conducting inclusions produced by gas pressure infiltration. The volume fraction of non-conducting phase, namely equiaxed or angular alumina particles of various sizes and size-distributions embedded in a

In the pressure infiltration of metal matrix composites, molten metal is injected under external pressure into a porous preform of the reinforcing material. Equilibrium capillary parameters characterizing wetting for this process are summarized in plots of ...

Al/SiC composites with volume fractions of SiC between 0.55 and 0.71 were made from identical tapped and vibrated powder preforms by squeeze casting (SC) and by two different setups for gas pressure infiltration (GPI), one that allows short (1-2 min) liqui ...

Composite materials are often produced by pressure-infiltration of a liquid matrix into a preform of packed solid fibers or particles. Capillary forces that intervene in this process are quantified by measuring saturation curves, which are plots of the fraction pore space filled with the matrix versus the pressure difference between the matrix and the atmosphere initially present in the porous preform to be infiltrated. We have constructed an apparatus capable of measuring saturation curves at high temperat

The in situ matrix flow stress of continuous fibre-reinforced aluminium is measured in tension along the fibre axis. We use a new, tighter, estimate for the effect differential Poisson contraction between fibres and matrix and take into consideration nonli ...

The high-temperature wettability of alumina particulate preforms by copper is investigated by means of infiltration experiments conducted at 1473 K under low oxygen partial pressure. Wetting is quantified in terms of drainage curves, which plot the volume ...

The effect of diamond surface treatment on the Thermal Boundary Conductance (TBC) between Al and diamond is investigated. The treatments consist in either of the following: exposition to a plasma of pure Ar, Ar:H and Ar:O, and HNO3:H2SO4 acid dip for vario ...

In this work, the macrotexture of dense Zn produced by laser powder bed fusion (LPBF) was studied and the mechanical properties for different tensile bar orientations were measured. The compressive strength of LPBF Zn scaffolds with five different unit cel ...

The thermal conductivity of aluminum matrix composites having a high volume fraction of SiC particles is investigated by comparing data for composites fabricated by infiltrating liquid aluminum into preforms made either from a single particle size, or by m ...

The contact angles of two different systems, molten silicon and a eutectic Si-8 at. pct Zr alloy and their evolution over timeon vitreous carbon and polycrystalline silicon carbide (SiC) substrates were investigated at 1500 degrees C under vacuum, as well ...

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 ...

Copper matrix composites reinforced with low thermal expansion ceramic particles, i.e. SiO2, AIN and diamond, in the range of ceramic volume fractions between 0.55 and 0.85 have been prepared by gas pressure infiltration and are characterized by their coef ...

An effective hydrogen diffusion coefficient has been calculated for two solidifying Al - 4.5 wt.% Cu and Al - 10 wt.% Cu alloys as a function of the volume fraction of solid. For this purpose, in situ X-ray tomography was performed on these alloys. For eac ...

The influence of particle size and particle type on the fracture toughness of aluminium matrix composites is investigated using model composites of 99.99% purity aluminium reinforced with particles of alumina and boron carbide. These composites are produced by gas pressure infiltration, and feature a volume fraction of reinforcement near 50 vol pet. The average particle size is varied between 5 and 35 mum. Fracture properties are determined using the single specimen J-integral test method. Observations of c

Aluminum nitride (AlN) particle reinforced metal-matrix-composites produced by pressure infiltration are characterized in terms of their thermal conductivity. The composites are designed to cover a wide range of phase contrast between the dispersed particl ...

In this work, the mechanisms leading to the pore closure in reactive melt infiltration (RMI) of carbon by pure silicon and a near eutectic Si-8 at-pct Zr alloy at 1500 and 1700 degrees C under vacuum were studied. Various geometrical configurations of micr ...

We extend here a “bottleneck” flow model derived earlier for incompressible fluids flowing under creeping flow conditions [Despois, J. and Mortensen, A: Acta Materialia 53 (2005) 1381] to flow regimes where inertial losses are no longer negligible, causing ...

Pore-free composites combining alumina particles within a matrix of pure aluminium are produced by pressure infiltration, varying systematically the degree of the contiguity, beta, of the ceramic phase by sintering prior to infiltration. The thermal expans ...

Ludger Weber

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Mechanical properties of replicated cellular Zn and Zn1.5Mg in uniaxial compression

Towards a coherent database of thermal boundary conductance at metal/dielectric interfaces

On the electrical conductivity of metal matrix composites containing high volume fractions of non-conducting inclusions

Capillarity in pressure infiltration: improvements in characterization of high-temperature systems

Influence of processing route on electrical and thermal conductivity of Al/SiC composites with bimodal particle distribution

Capillarity in pressure infiltration: influence of percolation and wetting angle

In situ flow stress of pure aluminium constrained by tightly packed alumina fibres

Wetting in infiltration of alumina particle preforms with molten copper

Influence of diamond surface termination on thermal boundary conductance between Al and diamond

Mechanical properties and cytocompatibility of dense and porous Zn produced by laser powder bed fusion for biodegradable implant applications

Thermal conductivity of Al-SiC composites with monomodal and bimodal particle size distribution

Studying the wettability of Si and eutectic Si-Zr alloy on carbon and silicon carbide by sessile drop experiments

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

Influence of the elastic properties of the phases on the coefficient of thermal expansion of a metal matrix composite

Effective hydrogen diffusion coefficient for solidifying aluminium alloys

Fracture toughness determination of high volume fraction particle reinforced aluminium matrix composites

Thermal conductivity and interfacial conductance of AlN particle reinforced metal matrix composites

Liquid metal infiltration of silicon based alloys into porous carbonaceous materials. Part II: Experimental verification of modelling approaches by infiltration of Si-Zr alloy into idealized microchannels

Fluid flow through replicated microcellular materials in the Darcy-Forchheimer regime

Influence of reinforcement contiguity on the thermal expansion of alumina particle reinforced aluminium composites