Development of lanthanum strontium cobalt ferrite perovskite electrodes of solid oxide fuel cells – A review

Fundamental mechanisms involved in the degradation of nickel–yttria stabilized zirconia (Ni–YSZ) anode during solid oxide fuel cells operation: A review

Fuel cells offer the possibility of zero-emissions electricity generation and increased energy security. We review here the current status of solid oxide (SOFC) and polymer electrolyte membrane (PEMFC) fuel cells. Such solid electrolyte systems obviate the need to contain corrosive liquids and are thus preferred by many developers over alkali, phosphoric acid or molten carbonate fuel cells. Dramatic improvements in power densities have been achieved in both SOFC and PEMFC systems through reduction of the electrolyte thickness and architectural control of the composite electrodes. Current efforts are aimed at reducing SOFC costs by lowering operating temperatures to 500–800 °C, and reducing PEMFC system complexity be developing ‘water-free’ membranes which can also be operated at temperatures slightly above 100 °C.

Fuel cell materials and components

Dense, crack-free, uniform, and well-adhered environmental barrier coatings (EBCs) are required to enhance the environmental durability of silicon (Si)-based ceramic matrix composites in high pressure, high gas velocity combustion atmospheres. This paper represents an assessment of different thermal spray techniques for the deposition of Yb2Si2O7 EBCs. The Yb2Si2O7 coatings were deposited by means of atmospheric plasma spraying (APS), high-velocity oxygen fuel spraying (HVOF), suspension plasma spraying (SPS), and very low-pressure plasma spraying (VLPPS) techniques. The initial feedstock, as well as the deposited coatings, were characterized and compared in terms of their phase composition. The as-sprayed amorphous content, microstructure, and porosity of the coatings were further analyzed. Based on this preliminary investigation, the HVOF process stood out from the other techniques as it enabled the production of vertical crack-free coatings with higher crystallinity in comparison with the APS and SPS techniques in atmospheric conditions. Nevertheless, VLPPS was found to be the preferred process for the deposition of Yb2Si2O7 coatings with desired characteristics in a controlled-atmosphere chamber.

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Yb2Si2O7 Environmental Barrier Coatings Deposited by Various Thermal Spray Techniques: A Preliminary Comparative Study

Suspension and solution plasma spraying makes it possible to achieve coatings with fine microstructural features and is becoming a common route in laboratories to elaborate coatings a few tenths to a few hundreds of micrometres thick. This paper presents the recent developments in direct current plasma spraying of suspensions or solutions. It begins with a short description of the main plasma torches used for liquid feedstock spraying as well as the techniques used to experimentally observe droplets and particles in the plasma jet and characterize the void network of nanostructured plasma-sprayed coatings. The paper then turns to the momentum and heat transfers between fine particles and the plasma jet and the interactions between the plasma jet and a liquid in the form of a jet or drops. It concludes by linking some characteristic features of coating microstructures with the liquid processing in the plasma jet.

https://iopscience.iop.org/article/10.1088/0022-3727/46/22/224015/pdf

Suspension and solution plasma spraying

A fast response thermocouple for internal combustion engine surface temperature measurements

Electrochemical performance of solid oxide fuel cells having electrolytes made by suspension and solution precursor plasma spraying

Yttria-stabilized zirconia electrolyte coatings for solid oxide fuel cells were deposited by suspension plasma spraying using a range of spray conditions and a variety of substrates, including finely structured porous stainless steel disks and cathode layers on stainless steel supports. Electrolyte permeability values and trends were found to be highly dependent on which substrate was used. The most gas-tight electrolyte coatings were those deposited directly on the porous metal disks. With this substrate, permeability was reduced by increasing the torch power and reducing the stand-off distance to produce dense coating microstructures. On the substrates with cathodes, electrolyte permeability was reduced by increasing the stand-off distance, which reduced the formation of segmentation cracks and regions of aligned and concentrated porosity. The formation mechanisms of the various permeability-related coating features are discussed and strategies for reducing permeability are presented. The dependences of electrolyte deposition efficiency and surface roughness on process conditions and substrate properties are also presented.

Permeability and Microstructure of Suspension Plasma-Sprayed YSZ Electrolytes for SOFCs on Various Substrates

Fabrication and characterization of solid oxide fuel cell cathodes made from nano-structured LSCF–SDC composite feedstock

An investigation of metal and ceramic thermal barrier coatings in a spark-ignition engine Michael Anderson Marr Master of Applied Science Graduate Department of Mechanical and Industrial Engineering University of Toronto 2009 Surface temperature and heat flux measurements were made in a single cylinder SI engine piston when uncoated and with two different surface coatings: a metal TBC and YSZ. A new thermocouple was developed to accurately measure surface temperatures. The engine was operated in a standard full load mode and a knock promoting mode featuring heated intake air and advanced spark timing. Cylinder pressures were measured to quantify knock. It was found that average heat flux into the piston substrate was 33 % higher with the metal TBC and unchanged with the YSZ relative to the uncoated surface. The increase with the metal TBC was attributed to its surface roughness. However, the metal TBC and YSZ reduced peak heat flux by 69 and 77 %, respectively. Both the metal TBC and YSZ reduced knock compared to the uncoated surface. After testing, the metal TBC was undamaged and the YSZ was slightly chipped.

/pdf/an-investigation-of-metal-and-ceramic-thermal-barrier-1d3f8q9ic4.pdf

Michael Marr

Papers

A fast response thermocouple for internal combustion engine surface temperature measurements

Electrochemical performance of solid oxide fuel cells having electrolytes made by suspension and solution precursor plasma spraying

Permeability and Microstructure of Suspension Plasma-Sprayed YSZ Electrolytes for SOFCs on Various Substrates

Fabrication and characterization of solid oxide fuel cell cathodes made from nano-structured LSCF–SDC composite feedstock

An Investigation of Metal and Ceramic Thermal Barrier Coatings in a Spark-Ignition Engine