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Pulsed Wire Evaporation(PWE) Method으로 제조된 나노 NiO 분말의 SOFC 연료극 기능성층으로의 적용

김혜원,김동주,박석주,임탁형,이승복,신동렬,윤순길,송락현 한국수소및신에너지학회 2009 한국수소 및 신에너지학회논문집 Vol.20 No.6
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  ScienceON
  
  DBpia
In present work, NiO/YSZ anode functional layer was prepared by nano NiO powder and 8YSZ powder. The nano NiO powders were made by Pulsed wire evaporation (PWE) method. Nano NiO- YSZ functional layer was sintered at the temperature of 900-1400℃. The prepared functional layer was characterized by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy. The nano NiO- YSZ anode functional layer sintered at 1300℃ shows the lowest polarization resistance. Nano NiO- YSZ anode functional layer shows about two times smaller polarization resistance than the anode functional layer made by commercial NiO-YSZ powders. Based on these experimental results, it is concluded that the nano NiO-YSZ cermet is suitable as a anode functional layer operated at 800℃.
2
Three-dimensional thermal stress analysis of the re-oxidized Ni-YSZ anode functional layer in solid oxide fuel cells

Kim, Jun Woo,Bae, Kiho,Kim, Hyun Joong,Son, Ji-won,Kim, Namkeun,Stenfelt, Stefan,Prinz, Fritz B.,Shim, Joon Hyung Elsevier 2018 JOURNAL OF ALLOYS AND COMPOUNDS Vol.752 No.-
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Abstract Nickel-yttria-stabilized zirconia (Ni-YSZ) cermet is widely used as an anode material in solid oxide fuel cells (SOFCs); however, Ni re-oxidation causes critical problems due to volume expansion, which causes high thermal stress. We fabricated a Ni-YSZ anode functional layer (AFL), which is an essential component in high-performance SOFCs, and re-oxidized it to investigate the related three-dimensional (3D) microstructural and thermo-mechanical effects. A 3D model of the re-oxidized AFL was generated using focused ion beam-scanning electron microscope (FIB-SEM) tomography. Re-oxidation of the Ni phase caused significant volumetric expansion, which was confirmed via image analysis and calculation of the volume fraction, connectivity, and two-phase boundary density. Finite element analysis (FEA) with simulated heating to 500–900 °C confirmed that the thermal stress in re-oxidized Ni-YSZ is concentrated at the boundaries between YSZ and re-oxidized NiO (nickel oxide). NiO is subjected to more stress than YSZ. Stress exceeding the fracture stress of 8 mol% YSZ appears primarily at 800 °C or higher. The stress is also more severe near the electrolyte-anode boundary than in the Ni-YSZ cermet and the YSZ regions. This may be responsible for the electrolyte membrane delamination and fracture that are observed during high-temperature operation. Highlights <UL> <LI> Re-oxidized NiO-YSZ was 3D-reconstructed via FIB-SEM tomography. </LI> <LI> Re-oxidation of Ni-YSZ removes pores via Ni volume expansion. </LI> <LI> The NiO-YSZ interface and the YSZ electrolyte exhibit high thermal stress. </LI> <LI> Thermal stresses greater than the fracture stress of YSZ appear at some interfaces. </LI> </UL>