Effect of electric load and dual atmosphere on the properties of an alkali containing diopside-based glass sealant for solid oxide cells

© 2019 Elsevier B.V. All rights reserved.A new alkali-containing diopside based glass-ceramic sealant for solid oxide cells was synthesized, characterized and tested. The composition was designed to match the coefficient of thermal expansion (CTE) of Crofer22APU interconnect. The sealant has a glass transition temperature of 600°C, a crystallization peak temperature of 850°C and a maximum shrinkage temperature of 700°C, thus suggesting effective densification prior to crystallization. The CTE of the glass-ceramic is 11.5 10-6 K-1, a value which is compatible with the CTE for Crofer22APU stainless steel. Crofer22APU/glass-ceramic/Crofer22APU joined samples were tested in simulated real-life operating conditions at 800°C in dual atmosphere under an applied voltage, monitoring the electrical resistivity. The effect of two different applied voltages (0.7V and 1.3V) was evaluated. A voltage of 1.3V led to a rapid decrease in the electrical resistivity during the test;such a drop was due to the formation of Cr2O3 “bridges” that connected the two Crofer22APU plates separated by the sealant. There was no decrease in the resistivity when a voltage of 0.7V was applied. Instead,resistivity value remained stable at around 105 Ω cm for the 100h test duration. The degradation mechanisms, due to both the alkali content and the applied voltage, are investigated and discussed.Peer reviewe

JV TASK - PREDICTIVE COAL QUALITY EFFECTS SCREENING TOOL (PCQUEST)

PCQUEST, a package of eight predictive indices, was developed with U.S. Department of Energy (DOE) support by the Energy and Environmental Research Center to predict fireside performance in coal-fired utility boilers more reliably than traditional indices. Since the development of PCQUEST, the need has arisen for additional fuel types into the program database. PCQUEST was developed using combustion inorganic transformation theory from previous projects and from empirical data derived from laboratory experiments and coal boiler field observations. The goal of this joint venture project between commercial industry clients and DOE is to further enhance PCQUEST and improve its utility for a variety of new fuels and systems. Specific objectives include initiating joint venture projects with utilities, boiler vendors, and coal companies that involve real-world situations and needs in order to strategically improve algorithms and input-output functions of PCQUEST, as well as to provide technology transfer to the industrial sector. The main body of this report provides a short summary of the projects that were closed from February 1999 through June 2006. All of the reports sent to the commercial clients can be found in the appendix

Friction velocity dependence, cohesion, and XRD data of marine sediments from IODP Site U1301, Juan de Fuca plate

To investigate the lithostratigraphic position and frictional behavior of the shallow plate boundary fault at the northern Cascadia subduction zone, we conducted laboratory friction experiments on sediments recovered at IODP Site U1301. We used a single-direct shear device under room temperature conditions with 3.5% simulated seawater to perform cohesion tests, plate rate tests and velocity step tests (VST). Friction data from VSTs were inversly modelled to obtain rate- and state friction (RSF) parameters

Chromium Vaporization From Alumina-Forming and Aluminized Alloys

The Cr vaporization from alumina-forming and aluminized alloys was investigated at temperatures between 800 degrees C and 1000 degrees C using the transpiration method. The growth of alumina scale was studied by XRD, SEM/EDX, SNMS and TEM and discussed in the context of Cr vaporization. The experiments show that chromium vaporization from thermally grown alumina scales on alloys is about three orders of magnitude lower than that from pure chromia. The results indicate that Cr vaporization is governed by the content of dissolved Cr in the alumina scale. Bulk diffusion is identified as the major transport mechanism of Cr through the alumina scale. With regard to Cr vaporization as a major reason for long-term degradation in SOFCs the results show that alumina-forming-alloys and aluminized surfaces are promising for application in SOFC components without a current-conducting function. (C) 2008 Elsevier B.V. All rights reserved

Friction velocity dependence of sediments from the Nankai Trough, Japan

To investigate frictional behavior of sediments along the Kumano transect in the Nankai Trough, Japan, friction experiments were conducted using a single-direct shear device at MARUM, University of Bremen under room temperature conditions with 3.5% simulated seawater. Intact sediment cores from the input, prism toe, and inner prism sites collected by the IODP NanTroSEIZE project were tested. In this dataset, parameters of the rate- and state-dependent friction law for each sample were reported, which were obtained by the velocity step tests from 0.01 to 30 μm/sec

Reduction of Chromium Vaporization from SOFC Interconnectors by Highly Effective Coatings

The vaporization of Cr-rich volatile species from interconnector materials is a major source of degradation that limits the lifetime of planar SOFC systems with metallic interconnects. In this study, the vaporization of Cr species of a variety high chromium alloys was studied at 800 degrees C in air using the transpiration method. The measured release of Cr species of the different alloys was correlated with the formed outer oxide scales. A quantitative estimation showed that all the investigated alloys failed to meet the requirements concerning the Cr release from interconnector materials for SOFCs or formed oxide scales which possessed too high electrical resistances. Sputtered ceramic coatings of LSM and LSC and metallic coatings of Co, Ni and Cu were tested with regard to their suitability for Cr retention. The sputtered perovskite coatings turned out to be ineffective in reducing the Cr release to the desired levels. With metallic coatings of Co, Ni or Cu the Cr release could be reduced by more than 99%. The metallic coatings and their oxides effectively reduced the growth of the oxide scale on the steel substrate and showed negligible vaporization rates for Co, Cu and Ni, respectively. Therefore, Co, Ni or Cu were identified as promising and cheap coating materials for metallic interconnectors. (c) 2006 Elsevier B.V. All rights reserved