小型試験法を用いたセリア系セラミックスの破壊特性に及ぼす希土類酸化物添加の影響評価

概要

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The influences of the sintering additive content of rare-earth oxide (Y_2O_3, Gd_2O_3, Sm_2O_3) on microstructure and mechanical properties of ceria ceramics were investigated by scanning electron microscopy and small specimen technique. A small punch testing method was employed to detemine the elastic modulus and biaxial fracture stress of the ceria-based ceramics, and the fracture toughness was estimated by vickers indentation method. Rare-earth oxides doped ceria powders with a composition of (CeO_2)_<1-x>(RO_<1.5>)_x(R=Y, Gd, Sm and x=0, 0.10, 0.15, 0.20, 0.30, 0.40, 1.00) were prepared by a coprecipitation method. The powders were compacted by die pressing (50MPa) followed by cold isostatic pressing (120MPa), and sintered at 1500℃ in air for 5h. Grain growth in the rare-earth oxides doped ceria ceramics were significantly suppressed, compared to the pure ceria ceramics. However, the elastic modulus, fracture stress and fracture toughness were decreased significantly with increasing additive content of the rare-earth oxides, possibly due to the oxygen vacancies induced by the rare-earth oxides doping. The experimental results suggest that the change in the mechanical properties should be taken into account in the use of ceria-based ceramics for solid oxide fuel cells, in addition to the improvement of oxygen ion conductivity.
一般社団法人日本機械学会の論文
2004-02-25