Degradation of Conductivity and Microstructure under Thermal and Current Load in Ni-YSZ Cermets for SOFC Anodes

Karl Thydén; Rasmus Barfod; Yi Lin Liu

doi:10.4028/www.scientific.net/AST.45.1483

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Layered Interphases in Ceramic Matrix Composites and Relation with Interfacial Behaviour
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Measurement and Simulation of the Oxidation of Carbon Fibers and C/SiC Ceramic
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HomeAdvances in Science and TechnologyAdvances in Science and Technology Vol. 45Degradation of Conductivity and Microstructure...

Degradation of Conductivity and Microstructure under Thermal and Current Load in Ni-YSZ Cermets for SOFC Anodes

Abstract:

The degradation of electrical conductivity in porous nickel-yttria stabilized zirconia composite cermets in a H2/H2O atmosphere under high temperature treatments has been investigated. The parameters varied were: temperature, water partial pressure, and electrical current load. The microstructure was analyzed before and after the treatment by optical microscopy and field emission scanning electron microscopy (FE-SEM). From the optical images the particle size and total amount of Ni, as area fraction, in the sample were measured. By the use of charge contrast (CC) in the FE-SEM particle size and area fraction of percolated Ni was measured. Temperature proved to have the largest effect on the degradation. Samples tested at 1000°C, in contrast to 750°C, showed a severe decrease of conductivity and growth of Ni particles. Higher water partial pressure accelerated Ni particle growth at both temperatures, but the loss of percolation and conductivity at 1000°C was less severe under high water partial pressure. A possible explanation for this behavior is discussed.