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Aïcha Hessler-Wyser

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Publications associées (100)

Mechanical and microstructural integrity of nickel-titanium and stainless steel laser joined wires

Jean-Marie Drezet, Aïcha Hessler-Wyser, Michel Rappaz, Alireza Karimi, Jonas Vannod

The biomedical industry shows increasing interest in the joining of dissimilar metals, especially with the aim of developing devices that combine different mechanical and corrosive properties. As an example, nickel titanium shape memory alloys joined to st ...

Elsevier2011

Cathode thickness-dependent tolerance to Cr-poisoning in solid oxide fuel cells

Aïcha Hessler-Wyser, Christos Comninellis, Jan Van Herle, Josef Andreas Schuler, Pietro Tanasini

This work aimed to set new guidelines for the quantification of Cr accumulation in solid oxide fuel cell cathodes after operation, and enabled to pinpoint a diffusion-controlled tolerance to Cr-poisoning for increased cathode thickness; the additional cath ...

Elsevier2010

Properties of interfaces in amorphous/crystalline silicon heterojunctions

Christophe Ballif, Aïcha Hessler-Wyser, Christian Monachon, Stefaan De Wolf, Luc Fesquet

To study recombination at the amorphous/crystalline Si (a- Si:H/c-Si) heterointerface, the amphoteric nature of silicon (Si) dangling bonds is taken into account. Modeling interface recombination measured on various test structures provides insight into th ...

Wiley2010

Modification of textured silicon wafer surface morphology for fabrication of heterojunction solar cell with open circuit voltage over 700mV

Christophe Ballif, Aïcha Hessler-Wyser, Stefaan De Wolf, Luc Fesquet

Crystalline silicon wafer (c-Si) can be extremely well passivated by plasma enhanced chemical vapor deposited (PECVD) amorphous silicon (a-Si:H) films. As a result, on flat substrates, solar cells with very high open circuit voltage are readily obtained. O ...

2010

Rapid chromium quantification in solid oxide fuel cell cathodes

Aïcha Hessler-Wyser, Jan Van Herle, Josef Andreas Schuler, Pietro Tanasini

The detection and quantification of small quantities of Cr in (La,Sr)MnO3/Y–ZrO2 solid oxide fuel cell (SOFC) cathodes by energy-dispersive X-ray spectroscopy (EDXS) is not straightforward as Cr X-ray emission lines overlap with La/Mn and O lines. This wor ...

Elsevier2010

Air Side Contamination in SOFC Stack Testing

Aïcha Hessler-Wyser, Jan Van Herle, Zacharie Wuillemin, Josef Andreas Schuler, Christian Gehrig, Christian Ludwig

Solid Oxide Fuel Cells (SOFCs) are likely candidates for electricity production with high efficiency and promise reasonable fuel tolerance. While fuel impurities are known anode poisons, less attention is brought to air-purity, especially to air-side conta ...

2010

Characterisation of Laser Welds, between Nitinol and Stainless Steel Wires

Aïcha Hessler-Wyser, Michel Rappaz, Jonas Vannod

Nickel-Titanium (NiTi) shape memory alloys are often used in medical component devices, for instance as guide wires for neurological surgery applications. Manufacturing of such devices becomes more and more challenging, especially considering the need to j ...

2009

In situ reduction and oxidation of nickel from solid oxide fuel cells in a Titan ETEM

Aïcha Hessler-Wyser, Jan Van Herle, Antonin Faes, Quentin Thomas Jeangros

Solid Oxide Fuel Cells (SOFC) common technology is based on anode- supported cells composed of nickel-yttria stabilized zirconia (Ni-YSZ) cermet. The nickel is in oxide state (NiO) during SOFC production and is reduced to metallic nickel during the first o ...

2009

Nickel-Zirconia Anode Degradation and Triple Phase Boundary Quantification from Microstructural Analysis

Aïcha Hessler-Wyser, Jan Van Herle, Antonin Faes

Microstructural evolution of anode supported solid oxide fuel cells (SOFC) during medium-term stack testing has been characterized by scanning electron microscopy (SEM). Low acceleration voltage SEM imaging is used to separate the three anode phases (nicke ...

2009

Experimental and Theoretical Investigation of Degradation Mechanisms in SOFC Electrodes

Aïcha Hessler-Wyser, Christos Comninellis, Jan Van Herle, Antonin Faes, Pietro Tanasini

Performance degradation data obtained on single solid oxide fuel cells tested at 850°C with air and humidified H2 and using Ni-YSZ anode supported cells are presented. Microscopic investigation is carried out on both anode and cathode to quantify variation ...

2009

Sulfur as pollutant species on the cathode side of a SOFC system

Aïcha Hessler-Wyser, Jan Van Herle, Josef Andreas Schuler

Sulfur poisoning in a strontium doped lanthanum cobaltite (LSC) cathode current collection layer was revealed in a solid oxide fuel cell (SOFC) tested in repeat-element and stack configuration. Sources of sulfur contamination, other than trace SOx in air, ...

2009

RedOx study of anode supported solid oxide fuel cell

Aïcha Hessler-Wyser, Jan Van Herle, Arata Nakajo, Antonin Faes, David Dubois

The common technology for solid oxide fuel cells (SOFC) is based on a cermet (ceramic-metal composite) anode of nickel with yttria stabilized zirconia (YSZ), often used as the supporting structure. One of the main limitations of this technology is the tole ...

2009

In situ Reduction and Oxidation of Nickel from Solid Oxide Fuel Cells in a Transmission Electron Microscope

Aïcha Hessler-Wyser, Jan Van Herle, Antonin Faes, Quentin Thomas Jeangros

Environmental transmission electron microscopy was used to characterize in situ the reduction and oxidation of nickel from a Ni/YSZ solid oxide fuel cell anode support between 300-500°C. The reduction is done under low hydrogen pressure. The reduction init ...

2009

Redox study of anode supported solid oxide fuel cell

Aïcha Hessler-Wyser, Jan Van Herle, Antonin Faes

The common technology for solid oxide fuel cells (SOFC) is based on a cermet anode of nickel with yttrium stabilized zirconia (YSZ), often used as the supporting structure. One of the main limitations of this anode technology is the redox tolerance. In thi ...

2008

Quantitative study of anode microstructure related to SOFC stack degradation

Aïcha Hessler-Wyser, Jan Van Herle, Antonin Faes

As the performances of Solid Oxide Fuel Cells (SOFC) get attractive, long term degradation becomes the main issue for this technology. Therefore it is essential to localise the origin of degradation and to understand its processes in order to find solution ...

Springer-Verlag2008

Nd:YAG laser joining between stainless steel and nickel-titanium shape memory alloys

Aïcha Hessler-Wyser, Michel Rappaz, Jonas Vannod

Nickel-Titanium (NiTi) shape memory alloys are often used in medical component devices, for instance as guide wires for neurological surgery applications. The manufacture of such devices becomes more and more challenging, especially considering the need to ...

2008

TEM characterization of textured silicon heterojunction solar cells

Christophe Ballif, Aïcha Hessler-Wyser, Christian Monachon

Increasing the efficiency of crystalline silicon (c-Si) solar cells requires the reduction of both bulk and interface recombination. Even if bulk recombination is almost suppressed, the symmetry of the crystal lattice is disturbed at the surface and hence, ...

Springer2008

Rapid preparation and SEM microstructural characterization of nickel-yttria- stabilized zirconia cermets

Aïcha Hessler-Wyser, Jan Van Herle, Antonin Faes, Christian Monachon

Sample preparation and scanning electron microscopy imaging methods were developed to characterize solid-oxide fuel cell anodes made out of a nickel- yttria-stabilized zirconia porous cermet. The sample preparation uses only tripod polishing and does not r ...

2008

Textured silicon heterojunction solar cells with over 700mV open-circuit voltage studied by transmission electron microscopy

Christophe Ballif, Aïcha Hessler-Wyser, Christian Monachon, Stefaan De Wolf, Luc Fesquet

In this article, we report on the use of transmission electron microscopy (TEM) for the fabrication of high-performance textured amorphous/crystalline silicon (a-Si:H/c-Si) heterojunction (HJ) solar cells. Whereas classical thin-film characterization techn ...

2008

Etude de zones amorphes induites dans l'aluminium par implantation de nickel

Aïcha Hessler-Wyser

EPFL1999

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