| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1996: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1995: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
The main purpose of this study is sintering of calcite under atmospheric pressure. The establishment of this process should result in slowing down the increment of CO_2 content in the atmosphere. CaCO_3 and sintering aids, such as LiF,Li_2CO_3, NaCl, etc., were mixed with ball mill, and pressed into pellets. The green bodies were sintered in air or CO_2 atmosphere below their decomposition temperature. The obtained specimens were evaluated by apparent roughness. The addition of LiF gave the best sintered body within the experiments. I fixed on LiF as an aid of calcite sintering and determined the optimum sintering temperature range and the optimum amount of the additive. The best temperature range was between 525 and 550ﾟC and the best amount was.5wt%. The characterization of the excellent samples which were sintered in air or CO_2 atmosphere was carried out by scanni g electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). From the results of XRD,CaO and Ca (OH)_2 were detected in the sample sintered in air, while they were not detected in the samples sintered in CO_2 atmosphere. In order to study the mechanism of the sintering process, a grain boundary model was made, the preparation was as follows. LiF was sandwiched between large single crystals of calcite and treated at 575ﾟC for 12th in CO_2 atmosphere. Spherical crystal and eutectic mixture was observed in the model boundary by TEM,the former was CaF_2, the latter was made of CaCO_3 and LiF.DTA measurements were also performed on the mixture of CaCO_3 and LiF in carious amounts of LiF.The start temperature of endothermic peak was 540ﾟC,which was independent of the amount of LiF.The result suggests that an eutectic melt was formed at the temperature.
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