チタン酸バリウム磁器の焼結, 特に高温度におけるCO_2の放出過程について

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In the previous paper, the author reported on the sintering phenomenon of Barium Titanate ceramics, especially their expansion and shrinkage characteristics during the firing process. This time, in order to find out the best firing condition of Barium Titanate ceramics, the decomposition curve of BaCO3 at high temperature was measured. The method of measurement was to observe the change in the weight of test pieces continuously as a function of both temperature and time over the temperature range from room temperature to 1300°C, using a thermo-balance with strain meter. The results obtained are summarized as follows.(1) In the firing process of Barium Titanate, the libration of CO2 occurred over a temperature range from 600°C to 1100°C. It was made clear experimentally that the abnormal expansion phenomenon reported in the previous paper occurred when the escaping speed of CO2 exceeded 0.1cm3/sec per unit volume of sample.(2) In the reaction of decomposition librating CO2 at constant temperature, Janders equation has been valid exactly. Applying these results, the activation energy of reaction was calculated to be 73kcal/mol. Futhermore, applying this value, it was found that at a certain rate of temperature raising the calculated decomposition curve of BaCO3 coincided with experimental curve.(3) By adding clay to a few weight percent, the activation energy of reaction increased slightly and shrinkage reaction at higher temperature was accelerated considerably.(4) If the raising of temperature was kept at a rate of 0.8-12°C/min in the firing process, it was possible to avoid radical abnormal expansion phenomenon. Furthemore, by the experiments on frequency constant for radial mode vibration, residual polarization and so on it was made clear that the sample prepared under such condition showed excellent electrical and acoustic properties.(5) The thermo-balance with strain meter was very convenient for such an investigation as this, because it was possible to record the change of weight automatically within a limit of 1 milli-gram error.
社団法人日本セラミックス協会の論文
1958-03-01

チタン酸バリウム磁器の焼結, 特に高温度におけるCO_2の放出過程について

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