SOFC動作環境中における燃料極Ni-YSZサーメットの機械特性評価

概要

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Ni-YSZ composites are widely used as SOFC anode materials for electrochemical devices. The mechanical properties of Ni-YSZ composites were investigated by using a Small Punch(SP) testing method under SOFC operating condition. The compositions of the Ni-YSZ composites tested in this study were 0:100 vol.%, 15:85 vol.%, 30:70 vol.%, and 50:50 vol.%. Electrical resistivity measurements suggested that the Ni particles formed a network-like structure at the Ni content greater than 30 vol.%. Experimental results obtained from the SP tests demonstrated that ductile-like deformation was induced under a reducing environment for the Ni contents of 30 and 50 vol. %. The ductile-like behavior could be attributed to the formation of Ni network. The first complete re-oxidation of NiO-YSZ composites then caused critical damage and resulted in a drastic strength reduction, probably due to Ni agglomeration. This study revealed the first evidence for the presence of potential plastic deformation capacity in Ni-YSZ composites under reducing environment.