Wolfgang Schafbauer

Plansee (Austria)

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Norbert H. Menzler

Forschungszentrum Jülich

Hans Peter Buchkremer

Forschungszentrum Jülich

Martin Bram

Forschungszentrum Jülich

David Udomsilp

Forschungszentrum Jülich

Olivier Guillon

Forschungszentrum Jülich

Daniel Röhrens

RWTH Aachen University

Alexander K. Opitz

TU Wien

Wilhelm Albert Meulenberg

Forschungszentrum Jülich

Markus Haydn

Plansee (Germany)

Cornelia Bischof

Christian Doppler Laboratory for Thermoelectricity

Cooperative Institutions

Forschungszentrum Jülich

Plansee (Austria)

Jülich Aachen Research Alliance

Plansee (Germany)

Stadtwerke Jülich (Germany)

Interface (United States)

Christian Doppler Laboratory for Thermoelectricity

TU Wien

Universität Innsbruck

Instituto de Tecnología Química

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Solute-induced grain refinement and defect suppression in boron-modified molybdenum manufactured via laser powder-bed fusion

International Journal of Refractory Metals and Hard Materials (2023)

Lukas Kaserer Daniel Brennsteiner Jakob Braun Valerie Goettgens Ilse Letofsky‐Papst

Molybdenum manufactured with laser powder bed fusion (LPBF) has an undesirable coarse-grained, columnar microstructure interspersed with intergranular cracks, high porosity, and poor mechanical strength. These defects result from a combination of the harsh LPBF process conditions and the disadvantageous properties of molybdenum, such as its high brittle-ductile transition temperature and low tolerance for oxygen impurities. In order to suppress these defect-forming mechanisms and improve the suitability for LPBF, alloy-side material adjustments with simultaneous process optimization are necessary. In this work, the effect of adjusting Mo by adding 3.5 at.% B is investigated experimentally. Mo-3.5 at.% B specimens can be produced entirely free of cracks, with a density of 99.8%. The specimens have a microstructure of fine, equiaxed grains with an average grain size of 31 μm and an aspect ratio of 1.3, thus achieving substantial refinement of the otherwise typically coarse-grained columnar, anisotropic microstructure of pure Mo in LPBF. Furthermore, the grains possess a honeycomb-like cellular subgrain structure. This structure is formed through the solute rejection effect of B during the solidification and consists of initially solidified pure α-Mo cells with a cell size <1 μm and a honeycomb-like network of an ~100 nm thick intercellular Mo2B phase completely covering the α-Mo cells. In addition, the formation of boron oxide inclusions, presumably B2O3, with a size of <50 nm within the Mo2B phase, provides an effective mechanism for scavenging oxygen impurities, thus ensuring segregation-free grain boundaries in Mo-3.5 at.% B. The microstructural modifications substantially improve the mechanical properties. Under appropriate process conditions, with the substrate plate preheating temperature playing a crucial role, a bending strength of 1120 ± 172 MPa and a hardness of 379 ± 24 HV10 at room temperature can be achieved. At a test temperature of 600 °C, an increase in the bending strength to 2265 MPa is observed, and the bending angle simultaneously increases from 2° at room temperature to 35° at 600 °C. These findings indicate that the strength of Mo-3.5 at.% B is limited by the brittle behavior of the material at lower temperatures, at which residual defects are likely to initiate fracture.

Equiaxed crystals

Honeycomb

Brittleness

10.1016/j.ijrmhm.2023.106384

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Citations (2)

Metal-supported palladium membranes for hydrogen separation

Powder Metallurgy (2015)

Markus Haydn K. Ortner Thomas Franco Wolfgang Schafbauer Axel Behrens

The demand for clean and green energy has raised the consumption of hydrogen continuously during the last years. Hydrogen is most economically produced in large scale systems by methane steam reforming followed by pressure swing adsorption (PSA). However, with a rising demand for small-scale production of hydrogen, and as down-scaling to smaller PSA-systems ( < 500 Nm3/h H2) is not economic, a substantial demand for hydrogen generation using palladium membranes has emerged.Porous tubes made of an oxide dispersion strengthened powder metallurgy Fe-Cr alloy (trade name ITM) constitute the backbone for the thin solid Pd films. The tubes provide mechanical and chemical long-term stability in atmospheres with hydrogen- and carbon-species at operation temperatures up to 600°C. A porous ceramic diffusion barrier layer (DBL) is deposited between the ITM-backbone and the Pd thin-film to avoid Pd diffusion into the Fe-Cr substrate and thereby ensure long-term integrity of the system. The Pd thin-film with a thickness < 10 μm is applied onto the DBL by a proprietary coating technology.This paper describes the production route of a tube/diffusion-barrier-layer/Pd-membrane system, its structure and permeation properties.

Diffusion barrier

10.1179/0032589915z.000000000247

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Development of High Power Density Solid Oxide Fuel Cells (SOFCs) for Long-Term Operation

Materials science forum (2010)

Norbert H. Menzler Wolfgang Schafbauer Feng Han Oliver Büchler Robert Mücke

Solid oxide fuel cells (SOFCs) enable environmentally friendly energy to be produced with high efficiency. The market entry of SOFC systems depends on the functionality of the components and on the costs. The SOFC has not yet reached market maturity. This presentation focuses on the possibilities for manufacturing SOFCs with high power outputs and long-term durability by using manufacturing technologies feasible in industry. For the past 15 years, FZ Jülich has been developing large-size so-called anode-supported SOFCs (up to 200 x 200 mm²) with reproducibly high power output (> 2 A/cm² at 800°C). Novel technologies for high-capacity manufacturing such as tape casting and roller coating have been introduced. Additionally, newly developed thin-film techniques have led to power outputs of more than 3 A/cm² at 800°C and more than 1.5 A/cm² below 700°C. These high power densities open up new possibilities for the operation of SOFCs at low temperatures to ensure low degradation and therefore long lifetimes.

Tape casting

Power density

Degradation

10.4028/www.scientific.net/msf.654-656.2875

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Citations (13)

Towards novel applications of solid oxide fuel cells

Daniel Röhrens Robert Mücke Feng Han Markus Haydn Doris Sebold

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Metal-supported fuel cells (MSCs) - a new type of robust fuel cells

Martin Bram David Udomsilp Olivier Guillon Wolfgang Schafbauer Norbert H. Menzler

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Metal Supported SOFCs: Electrochemical Performance under Various Testing Conditions

ECS Transactions (2017)

Markus Haydn Cornelia Bischof David Udomsilp Alexander K. Opitz Gesara Bimashofer

To demonstrate the performance and reliability of MSCs (Metal Supported SOFCs), a systematic electrochemical characterization on button cells has been performed. The cell conditioning during the first heating-up is described in detail, since there is a significant difference to ESCs (Electrolyte Supported Cell) and ASCs (Anode Supported Cell). The focus of the present work is to show the influence of different anode materials, gas-flow rates, and operation temperatures on recorded i-V-curves. In some cases, fuel utilization rates were used, which are higher than commonly applied in button cell experiments. However, under these harsh conditions, the anode and the metal substrate must handle e.g. high humidity.This paper summarizes recent results on (i) manufacturing, (ii) appropriate test procedures, (iii) electrochemical testing, and (iv) influence of different anode layer materials for MSCs.

10.1149/07801.1993ecst

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Redox-Stability of a Planar Metal-Supported SOFC

ECS Transactions (2013)

Daniel Roehrens Oliver Büchler Doris Sebold Mark Kappertz Wolfgang Schafbauer

We report on the systematic examination of the redox behavior of a novel metal-supported SOFC cell type based on a porous Cr/Fe support and a thin YSZ-electrolyte layer applied by PVD methods. The oxidation of the Ni catalyst at the anode and the subsequent damage to the fuel cell microstructure is one of the main contributions to degradation of an SOFC. Our cell concept was tested for tolerance to cyclic oxidation and reduction of the anode, employing gravimetric and electron microscopy methods. The effects of redox cycling on the microstructure are examined and compared to corresponding results from state-of-the-art anode-supported SOFCs.

Gravimetric analysis

Degradation

10.1149/05701.0665ecst

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Citations (5)

Advanced Manufacturing Technology for Solid Oxide Fuel Cells

Ceramic engineering and science proceedings (2011)

Norbert H. Menzler Wolfgang Schafbauer Robert Mücke R. Kauert Oliver Büchler

This chapter contains sections titled: Introduction Manufacturing Technologies Manufacturing of Anode-Supported SOFCs Sintering of Multi-layerd Structures Implementation of Roll Coating Technology Green-in-Green Tape Casting of Half-Cells Summary and Outlook

10.1002/9781118095249.ch14

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Citations (1)

Redox stability of metal-supported fuel cells with nickel/gadolinium-doped ceria anode

Journal of Power Sources (2019)

Florian Thaler David Udomsilp Wolfgang Schafbauer Cornelia Bischof Yosuke Fukuyama

10.1016/j.jpowsour.2019.226751

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Citations (26)

Tape Casting of Anode Supports for Solid Oxide Fuel Cells at Forschungszentrum Jülich

International Journal of Applied Ceramic Technology (2012)

Wolfgang Schafbauer Norbert H. Menzler Hans Peter Buchkremer

This contribution describes the development of tape casting for solid oxide fuel cells (SOFCs) anode supports starting with the characterization of the powders and ending with manufacturing of cells for stack testing. After casting the support, full cells were prepared by screen printing and sintering of the functional layers. The results of single‐cell and stack tests of the novel SOFC will be discussed. The new cell showed excellent electrochemical performance in single‐cell tests with more than 1.5 A/cm 2 (800°C, 0.7 V). Furthermore, stack tests showed no significant difference from earlier standard cells when operated at 800°C with a current density of 0.5 A/cm 2 .

Tape casting

Characterization

Screen printing

10.1111/j.1744-7402.2012.02839.x

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Citations (66)