ZrO_2-CeO_2系焼結体の熱膨張と電気抵抗

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Hydroxides containing Zr and Ce were coprecipitated from Zr nitrate and Ce chloride solution by addition of NH4OH. CeO2 content in the samples was ranging from 0 to 21mol% CeO2. Calcination was carried out at 1, 000°C for 3 hours. Then the powder was pressed by isostatic pressure of 4, 000kg/cm2. Sintering was done at 1400°C for 1.5 hours in a SiC electric furnace and at 1, 670°C for 1.5 hours in a city gas furnace.12mol% CeO2 sample did not show expansion due to transformation of ZrO2. Tetragonal ZrO2 solid solution had 22.1kcal/mol of activation energy for electrical conduction, cubic ZrO2, however, had 30kcal/mol. In the case of 12mol% CeO2 mixture, electrical conductivities at 700°C, at 1, 000°C and at 1, 300°C were 1.57×104 ohm-cm, 1.34×103 ohm-cm and 3.24×102 ohm-cm respectively.Transformation temperatures from tetragonal phase to monoclinic were identical both by method of electrical resistance and by dilatometric method. Thermal expansion of 12mol% CeO2 showed 1.07% up to 1, 100°C. Lattice constants of solid solution were increased with increase of CeO2 content.Evaluation of the ZrO2-CeO2 mixtures sintered at 1, 400°C for 1.5 hours in the SiC furnace as oxide heating elements, was worse than mixtures in the system ZrO2-CaO or ZrO2-Y2O3, because of value of electrical resistance and activation energy of electrical conduction.
社団法人日本セラミックス協会の論文
1965-02-01