127 research outputs found
Manufacturing and Performance of supported BSCF-Membranes for oxygen separation
No full textManufacturing and Performance of supported BSCF-Membranes for oxygen separationNiehoff, P. (Corresponding Author)* ; Schulze-Küppers, F. * ; Baumann, S. * ; Vassen, R. * ; Buchkremer, H. P. * ; Meulenberg, W. A. *2015Wiley Interscience Hoboken, NJCeramic engineering and science proceedings 35(8), 325-335 (2015) G
Dense membranes for oxygen and hydrogen separation (DEMOYS): project overview and first results
No full textThis paper provides an overview of objectives, structure and first results of the DEMOYS project, financially
supported by the European Commission in the frame of the 7th FP Energy. The project started on May 1, 2010 and
brings together fifteen Partners, including three Universities, five Research Organizations and seven Industries. The objective of DEMOYS is the development of thin mixed conducting membranes for O2 and H2 separation by using a new depostion technique Plasma Spraying - Thin Film (PS-TF) in combination with nano-porous, highly catalytic
layers
Characterization of defectiveness of oxygen transport membranes deposited by Low Pressure Plasma Spraying – Thin Film processes
No full textMicrostructural characterization of porous thermal barrier coatings by IR gas porosimetry and sintering forecasts
No full textIt is known that the thermal diffusivity of plasma sprayed coatings is quite sensitive to the operating conditions, namely the composition and pressure of the operating atmosphere. This makes it possible, in principle, to obtain information, in a non-destructive way, on the microstructure of thermal barrier coatings (TBCs) from thermal diffusivity measurements. An experimental assessment of this idea is presented in this paper. The microstructure of as-sprayed and sintered free-standing atmospheric plasma sprayed YPSZ TBC samples have been characterized by a new technique, named infrared (IR) gas porosimetry, as well as by mercury intrusion porosimetry and image analysis. The results from these different techniques have been compared. Furthermore, the microstructure and thermal diffusivity of sintered samples have been compared with the sintering forecasts produced by Cipitria’s sintering code coupled with the Bruggeman model for thermal diffusivity estimation. Sample-to-sample variations have been discussed and uncertainties in experimental techniques have been analysed. Conditions for accurate microstructural estimations have been obtained and suggestions on the reliability of the statistical evaluation are provide
Frequency metrology in quantum degenerate helium
No full textUbachs, W.M.G. [Promotor]Vassen, W. [Copromotor
Residual stresses and elastic modulus of thermal barrier coatings graded in porosity
No full textZirconia (ZrO2) stabilized with 8 wt.% Y2O3 is the most common material to be applied in thermal barrier coatings (TBC) owing to its excellent properties: low thermal conductivity; high toughness and thermal expansion coefficient similar to iron. Nevertheless, in order to increase the coatings lifetime, improvements in their thermomechanical behavior are still needed. With that purpose, we propose in this paper a graded ceramic coating. These TBC have been produced by depositing a conventional NiCoCrAlY bond coat on a Inconel 738 LC substrate followed by an atmospheric plasma sprayed top coat of ZrO2–8wt.%Y2O3 with a porosity gradient along the cross section.
The aim of the present contribution is to study residual stresses and elastic properties of the coating as a function of the porosity gradient.
For the characterization of the TBCs residual stresses, we have used Raman and X-ray diffraction (XRD) in different thermal conditions: as sprayed, after thermal shock at 1000 8C, and annealing at 1100 8C in air during 100 h. The top coatings show compressive stresses near the interface with the bond coat. A decrease of the stress level is observed along the cross section towards the surface. The residual stresses increase after annealing, however, have smaller variations after thermal shock.
The elastic properties were evaluated by Brillouin scattering: the scattering of laser light by acoustic waves in the GHz frequency range. The spectra at different depths indicate that in the annealed condition the acoustic velocity increases when approaching the external surface
Performance of wear resistant MCrAlY coatings with oxide dispersion strengthening
No full textAiming to devise suitable materials for sliding wear protection at high temperature, aluminium oxide-dispersion strengthened (ODS) CoNiCrAlY coatings were manufactured by vacuum plasma spraying (VPS). Feedstock materials were ball-milled powders with 2, 10 and 30 wt% Al2O3 content. The ball-on-disc sliding wear behaviour of the coatings was tested at 750 °C against an Al2O3 counterpart, and compared to a pure CoNiCrAlY coating (obtained from a commercial feedstock not subjected to ball milling) and to an uncoated Ni-base superalloy.Sliding wear rates decrease from the uncoated superalloy (≈3 × 10−5 mm3/(N·m)) to the pure CoNiCrAlY coating (≈2 × 10−5 mm3/(N·m)) and to the ODS ones, with the notable exception of the 10 wt% Al2O3-containing sample.Analyses of worn samples indicate that pure CoNiCrAlY is subject to severe adhesive wear, mitigated by the formation of a thick (>1 μm) “glaze” layer via compaction and (probable) sintering of tribo-oxidized debris particles. Addition of Al2O3 particles to the CoNiCrAlY matrix can either enhance or worsen the “glaze” stability. Specifically, a coating strengthened with 30 wt% Al2O3 provides an especially good mechanical support to the “glaze”. This produces beneficial effects resulting in a particularly low wear rate of ≈3 × 10−6 mm3/(N·m)
p53 9aaTADs activate transcription as small peptides.
No full textThe predicted 9aaTADs in p53 from different species were tested for activation of transcription in LexA hybrid constructs. Similarity of p53 with Gal4 and Sox18 are highlighted. The construct 9p53, labelled with asterisk, has lower expression level compared with other constructs (S1 Fig). Animal picture from Flickr: Lowland Streaked Tenrec, Mantadia, Madagascar, Author: Frank Vassen; Elephant, Author: Jon Mountjoy; Igel (Hedgehog), Author: Mi chaela. All pictures have Creative Commons Attribution 2.0 Generic license.</p
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