Versatile gas calibration: flexible in composition and signal form by use of a gas mixing pump and an automated syringe.

The H2 effusion from H2 saturated glass powders, H2 permeation through the wall of blown glass bulbs, and H2 permeation through the wall of glass capillaries were applied to evaluate the permeability of hydrogen gas in a barium-aluminoborosilicate (BABS) glass. To validate these methods, two commercial glasses (vitreous silica and borosilicate) were used as a reference. Permeation values obtained from the different experiments agreed within a factor of 3 or less. The H2 permeability of BABS glass at temperatures close to ambient was found to be at least 3 orders of magnitude below that of borosilicate and silica glasses. The powder method, which requires minimal sample preparation efforts, turned out to provide easy access to the measurement of H2 permeability of glasses down to P=3.9×10−21mols−1Pa−1m−1.

The well established carrier gas analysis (CGA) method was used to test different hydrogen detectors comprising a thermal conductivity detector (TCD) and a metal oxide semiconducting (MOx) sensor. The MOx sensor provides high hydrogen sensitivity and selectivity, whereas the TCD exhibits a much shorter response time and a linear hydrogen concentration dependency. Therefore, the TCD was used for quantitative hydrogen concentration measurements above 50 µmol/mol. The respective calibration was made using N2/H2 gas mixtures. Furthermore, the hydrogen content and degassing behaviour of titanium hydride (TiH2‐x) was studied. This material turned out to be a potential candidate for a solid sample calibration. Vacuum hot extraction (VHE) coupled with a mass spectrometer (MS) was then calibrated with TiH2‐x as transfer standard. The calibration was applied for the evaluation of the hydrogen content of austenitic steel samples (1.4301) and the comparison of CGA‐TCD and VHE‐MS.

The production and optimisation of screen printing (SP) pastes containing La(0.58)Sr(0.42)Co(0.21)Fe(0.79)O(3-delta) and La(0.61)Sr(0.41)Co(0.19)Fe(0.79)O(3-delta) (LSCF) were investigated. The application of these nanopowders is supposed to improve the cathode's microstructure and increase its mechanical strength. Thirty seven pastes containing LSCF were carried out with variation in binders, dispersants and different particle size distribution. The rheological behaviour of these pastes was investigated. It was found that commercially available dispersant Solsperse 3000 resulted in the best suspension stability, achieving almost 55 times lower viscosity value for pastes containing 20 vol.-%, than pastes without any dispersants. The shear thinning behaviour was found to be favourable for the LSCF cathode deposition. A cathode made from the mixture of nano and submicron powder exhibits a polarisation resistance as low as 0.76 Omega cm(2) at 592 degrees C.

The thermally activated proton diffusion in BaZr 0.9 Y 0.1 O 3 - d was studied with electrochemical impedance spectroscopy (IS) and quasi-elastic neutron scattering (QENS) in the temperature range 300–900 K. The diffusivities for the bulk material and the grain boundaries as obtained by IS obey an Arrhenius law with activation energies of 0.46 eV and 1.21 eV, respectively. The activation energies obtained by IS for the bulk are 0.26 eV above 700 K and 0.46 eV, below 700 K. The total diffusivity as obtained by IS is by one order of magnitude lower than the microscopic diffusivity as obtained by QENS. The activation energies obtained by QENS are 0.13 eV above 700 K and 0.04 eV, below 700 K. At about 700 K, the diffusion constants for IS and QENS have a remarkable crossover, suggesting two processes with different activation energies.

The thermally activated proton diffusion in BaZr0.9Y0.1O3−δ was studied with electrochemical impedance spectroscopy (IS) and quasi-elastic neutron scattering (QENS) in the temperature range 300–900 K. The diffusivities for the bulk material and the grain boundaries as obtained by IS obey an Arrhenius law with activation energies of 0.46 eV and 1.21 eV, respectively. The activation energies obtained by IS for the bulk are 0.26 eV above 700 K and 0.46 eV, below 700 K. The total diffusivity as obtained by IS is by one order of magnitude lower than the microscopic diffusivity as obtained by QENS. The activation energies obtained by QENS are 0.13 eV above 700 K and 0.04 eV, below 700 K. At about 700 K, the diffusion constants for IS and QENS have a remarkable crossover, suggesting two processes with different activation energies.

The oxygen nonstoichiometry of Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF5582) was investigated by thermogravimetry resulting in values of 2.40 <(3 - delta)< 2.57 for the equilibrium oxygen content in the range 600 <= T/degrees C <= 900 and 1E-4 < pO(2)/bar < 0.4. The oxygen exchange kinetics was studied by electrical conductivity relaxation as a function of temperature in the range 550 <= T/degrees C <= 725 with chemical diffusion coefficients 1E-6 < D-chem/cm(2) s(-1) < 3E-5 and (k(chem)) = 64 +/- 12 kJ mol(-1). Self-diffusion and surface exchange coefficients, as well as ionic conductivities are estimated. (c) 2008 Elsevier B.V. All rights reserved.

This study compares the electrical transport and the oxygen exchange properties of two mixed conducting materials between 600 and , namely (LSCF) and (BSCF). Both materials were synthesized by spray pyrolysis and characterized by the electrical conductivity relaxation technique. LSCF has the higher electrical conductivity ( between 450 and ), while BSCF shows faster oxygen exchange kinetics and diffusion. The expansion of both materials between 600 and (, below up to at ) does not match with the common electrolytes for solid oxide fuel cells.

Screen printing pastes based on organic binder systems were developed for the production of dense electrolyte layers of Y0.16Zr0.84O1.92(8YSZ) on Ni/YSZ anode substrates for anode supported solid oxide fuel cells (SOFCs). Pastes with a solid loading up to 50vol.% (86wt.%) of YSZ powder and the adequate thixotropic behaviour for screen printing could be produced. Dense layers were obtained by sintering at 1430°C and were shown to be gas tight by window and He leakage test. The electrical conductivity of the dense layers and the resulting activation energy (96–99kJmol−1) were obtained from impedance spectra in the temperature range from 250°C to 900°C. The agreement with literature values indicates that performing layers have been obtained.

This study compares the electrical transport and the oxygen exchange properties of two mixed conducting materials between 600 and 800 degrees C, namely La0.6Sr0.4Co0.2Fe0.8O3-delta (LSCF) and Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF). Both materials were synthesized by spray pyrolysis and characterized by the electrical conductivity relaxation technique. LSCF has the higher electrical conductivity (257-412 S cm(-1) between 450 and 900 degrees C), while BSCF shows faster oxygen exchange kinetics and diffusion. The expansion of both materials between 600 and 800 degrees C (BSCF = 27.3 ppm/K, LSCF = 15.5 ppm/K below 700 degrees C up to 27.5 ppm/K at T > 800 degrees C) does not match with the common electrolytes for solid oxide fuel cells. (C) 2008 The Electrochemical Society.

Capable materials for solid oxide fuel cell cathodes have to provide high electrocatalytic activity for oxygen reduction as well as sufficient electronic conductivity and good ionic transport properties. This study compares the electrical transport properties and the oxygen exchange properties of two promising cathode materials for operating temperatures between 600 and 800 {degree sign}C: La0.6Sr0.4Co0.2Fe0.8O3-d and Ba0.5Sr0.5Co0.8Fe0.2O3-d. Both materials were synthesized by spray pyrolysis and characterised with respect to phase purity and to the element ratio by XRD and ICP-AES analysis. The sintering behaviour of the calcined powders and the coefficients of thermal expansion of dense sintered samples were studied by dilatometry. As important parameters for the oxygen exchange reaction the chemical surface exchange coefficients and chemical diffusion coefficients as well as the electrical conductivities are compared.

The Magnesium Powertrain Cast Components Project is a jointly sponsored effort by the US Department of Energy and the US Council for Automotive Research to determine the feasibility and practicality of producing a magnesium-intensive engine. Through FEA design activities, cost modeling, and extensive alloy testing, the Project seeks to determine the technical and economic requirements of a V6 engine, and which of several newly-developed, high temperature magnesium alloys will meet those requirements. An additional objective of the Project is to identify the fundamental scientific challenges of using magnesium alloys and casting processes in powertrain components, both within the current Project and for more advanced powertrain components. The areas of research that have been identified are: magnesium alloy development (structure-property relationships), phase equilibrium and computational thermodynamics, creep deformation mechanisms, casting (solidification) behavior, corrosion and recycling. These are presented and discussed. The goal of this objective of the MPCC Project is to promote new and strengthen existing magnesium scientific research in the North America.