Sing Yick

A new Coriolis slurry erosion tester design for improved slurry dynamics

Abstract The Coriolis slurry tester provides a means of discriminating between the resistance of different materials to slurry erosion damage under low interaction intensity (low impingement angle and low normal velocity impact) conditions. A new design of the rotor–specimen holder assembly has been evolved to provide better control of the slurry flow over and along test specimen surfaces. Wear patterns on tester components reveal that slurry flow is similar to that predicted theoretically. The effects that the less turbulent fluid flow has on the response of specimen materials to slurry erosion, as measured either by specific energy or erosion resistance parameters, are also discussed. The new tester overcomes the sensitivity of earlier designs to small variations in the dimensions of specimen holders, or specimen positioning inserts, consequent upon machining tolerances.

Thin Film Solid Oxide Fuel Cells Deposited by Spray Pyrolysis

Two techniques of spray pyrolysis, namely, electrostatic and pneumatic spray deposition, were used to deposit samaria-doped ceria (SDC) electrolyte and lanthanum strontium cobalt ferrite (LSCF) cathode on cermet or metal supported anodes for solid oxide fuel cells (SOFCs) operated at reduced temperature. The deposition processes, the properties of the deposited films, and the electrochemical performances of the fabricated cells are reported in this paper. The deposited SDC electrolytes were dense and gas-tight, and had good adhesion to the underlying anodes. The deposited LSCF cathode had a preferred morphology to facilitate the transport of oxygen gas and effective contact with the electrolyte. Button cell testing indicated that the SOFCs with electrolyte or cathode deposited by spray pyrolysis had good electrochemical performance. This study demonstrated that spray pyrolysis is a cost-effective process for fabricating thin film SOFCs, especially metal supported SOFCs.

A study of single particle–target surface interactions along a specimen in the Coriolis slurry erosion tester

Abstract The Coriolis test is used for evaluating the slurry erosion behaviour of materials. Experiments with a model single glass bead-in-water “slurry” have revealed the nature of, and extent of damage at, all contact sites along a soft copper specimen surface. The results confirm previous theoretical predictions that in the Coriolis test mode erodent particles interact with the specimen in a series of low angle impacts of decreasing angle, rebound height and normal velocity component along the specimen.

Electrochemical Properties of Low-Temperature Solid Oxide Fuel Cells Under Chromium Poisoning Conditions

Rapid performance degradations of solid oxide fuel cells were observed when the chromium-forming metallic alloys were used as interconnects. The formation of strontium chromium oxide (SrCrO4) on the surface of Sr-doped perovskite cathode was believed to be one of the main causes for the cell degradation. This chromium-poisoning effect was not mitigated when the operating temperature was lowered to 600°C. The SrCrO4 that formed mainly on the cathode surface was found in both La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) and Sm0.5Sr0.5CoO3 (SSCo) cathode, suggesting that all strontium-containing cathodes may develop low conductive chromite oxide compounds. However, this chromium-poisoning effect can be effectively mitigated by coating a protective layer on the surface of the interconnect.

Some effects of retrofit additives on automotive oil performance in sliding concentrated contact lubrication tests

Abstract Effects of doping crankcase lubricants with retrofit (supplementary) oil additives have been assessed in both a modified load capacity (microsample step loading seizure (SLS)) test in the four-ball wear machine and in pin-on-disc tests. Both tests confirm that, although increasing extreme pressure protection levels, organolead-based additive products completely inhibit the zinc dialkyldithiophosphate antiwear activity of commercially formulated oils. Direct friction coefficient monitoring in extended tests has also shown that friction increases signalling failure in the microsample SLS testing of various lubricants can be due to different lubricant behavioural transitions. Comparison of lubricant friction and wear behaviour of both doped and undoped oil in extended microsample SLS tests with that in pin-on-disc tests has provided a basis for interpretation of the former test results in terms of IRG lubrication failure transition diagrams.

A Study on Co and Cu Oxides as Sintering Aids for Sm0.2Ce0.8O1.9 Electrolyte

In this study, an addition of Co and Cu oxides to Sm0.2Ce0.8O1.9 (SDC) was studied to improve the SDC sinterability. It has been found that both Co and Cu oxide are very effective as sintering aids, and the SDC sintering temperature can be reduced from 1400°C without aids to below 1000°C with only 1at.% of either Cu or Co. As compared to the pure SDC, a slight decrease of ionic conductivity was observed in SDC with Cu sintering aid. There is no obvious effect on electrochemical property of SDC with Co sintering aid under 2.5at.%.

Metal-supported Solid Oxide Fuel Cell Operated at 400~600{degree sign}C

Metal-supported SOFCs potentially offer many advantages compared to conventional technology, such as low operating temperatures, reduced cost, and increased reliability. They are also a promising choice for applications that require quick start-up, good stability against thermal cycles and mechanical shock resistance such as Auxiliary Power Units (APU) for the automotive industry. The National Research Council of Canadas Institute for Fuel Cell Innovation (NRC-IFCI) has been working on the development of metal supported SOFCs since 2004. In this paper, a metal-supported SOFC with a samarium doped ceria (SDC)/scandia-stabilized zirconia (ScSZ) bilayer electrolyte was fabricated by a combination of pulsed laser deposition (PLD) and wet chemistry processing. The cell performance and aging characteristics were analyzed by AC impedance spectroscopy and current-voltage measurements during operation in the temperature range from 400oC to 600oC. The power generation characteristics at low temperatures of this metal- supported SOFC will be beneficial for quick start-up and is expected to alleviate the performance deterioration. These results at such an early stage of research is very promising for the future development of this technology.

Development Status of SOFC Cell and Stack Technology at NRC-IFCI

Solid Oxide Fuel Cell (SOFC) development was started at the National Research Council of Canada’s Institute for Fuel Cell Innovation (NRCIFCI) in 2003 with the goal to develop the next generation of SOFC’s for Canadian Industry. To accomplish this task, work focused on the development of low temperature cermet and metal supported cells, direct deposition methods, low temperature sintering, seal and stack technology. As of November 2006, 5 cm x 5 cm cermet supported cell performance has been improved to 900 mW/cm at 600°C. These components have been incorporated into short stacks developed at IFCI to continue the push to commercialize this technology. At the same time, direct deposition technology has progressed rapidly to the point where metal supported 5 x 5 cells can be fabricated using sintering temperatures below 850°C. Results of this work will be presented, along with the development path at IFCI.