Papers by Keyword: Metallic Interconnect

Abstract: Alloy 230 (also named Haynes® 230) was tested as interconnect for production of hydrogen via High Temperature Vapor Electrolysis (HTVE). Samples were oxidized at 800°C in the both atmospheres representative of the HTVE operating conditions: Ar-1%H2-9%H2O (for cathode side) and air (for anode side). The high temperature oxidation behaviour was studied in both atmospheres together with the electrical conductivity of the thermally grown oxide scales. Oxidation kinetics indicated lower oxidation rate in H2/H2O compared to air (kp = 3.8 .10-15 g2.cm-4.s-1 in H2/H2O and kp = 1.6 .10-14 g2.cm-4.s-1 in air). The corrosion products were characterized by scanning electron microscopy associated with X-ray diffraction analyses and energy dispersive X-ray analyses. The sample electrical behaviour was evaluated by determining the Area Specific Resistance (ASR). The ASR was higher in H2/H2O (ASR = 1 ohm.cm2) than in air (ASR = 0.04 ohm.cm2). The diffusion of proton or hydrogen containing species through the oxide scale is proposed to be responsible for the increase of the electrical conductivity in cathode side.

Abstract: The present paper is a review on the oxidation kinetics, electrical properties, chromium vaporization rate and microstructure investigations of oxide products formed on an uncoated Crofer 22 APU alloy and 1.4762 steel and coated by means of pulsed laser deposition and screen-printing methods with films of (La,Sr)CoO₃, (La,Ca)CrO₃, (La,Sr)CrO₃, (La,Sr)(Co,Fe)O₃ and MnCo₂O₄ in air and Ar-H₂-H₂O and Ar-CH₄-H₂O gas mixtures at 1023-1173 K for up to 1200 hrs. Microstructure investigations using SEM-EDS showed the influence of the reaction products formed in different atmospheres at the steel/coating interface on the electrical properties and Cr vaporization rate of these composite materials, which are used for construction of SOFC interconnects.

Abstract: The method of electrochemical extraction of oxygen from air employing a solid oxide electrolyte (SOE) is presented. The prototype of electrochemical oxygen generator (pump) for medical applications has been developed and fabricated. It is based on thin-walled tubular segments of YSZ electrolyte (170 μm) with LSM based electrodes (~20 μm). Different technologies: nanopowder production by laser ablation, casting of polymer-ceramic tapes, formation of electrodes-electrolyte green structures by radial magnetic pulsed compaction followed by cosintering at 1200°C, were used for segments fabrication. The magnetron sputtering method was applied to protect metallic interconnects (Crofer 22 APU) with (Mn-Co)3O4 layer. Presented oxygen generator prototype produced 9 liters of pure oxygen per hour under applied power of 50 W at 800°C. No noble metals were used in construction.

Abstract: Oxygen diffusion was measured at oxygen/cathode/electrolyte interfaces and at oxide scales/alloy interconnects in Solid Oxide Fuel Cells (SOFCs). A stable isotope oxygen exchange technique (16O/18O exchange) was adopted to label the diffusion profiles in the oxides, and secondary ion mass spectrometry (SIMS) depth profiles were examined to determine the diffusion coefficients in the oxide ceramic materials. Diffusivity of oxygen in LaMnO3 cathode was measured under polarized condition (that is, considering the electrochemical process and diffusion). Also, oxygen diffusion in the oxide scales formed on the alloy was measured to clarify the formation mechanism of oxide scale.