石灰石を添加した陶器素地の熱膨張特性
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概要
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Thermal expansion characteristics of green bodies composed of Toseki, Roseki and Kibushi clay as the fundamental raw materials and limestone as an additive constituent are discussed in relation to content of limestone added and to the particle size.The thermal expansion curves for low limestone bodies show that a profound shrinkage due to sintering following after decomposition of limestone occurs at about 900°C, and it proceeds on into the higher temperature range. Those for the bodies containing limestone much more than 10.5% show a drastic change from shrinkage to expansion at about 960°C. The expansion proceeds on up to 1050°C, but it is succeeded by shrinkage at the temperature. Since the expansion can be observed only within the definite range of temperature (960°-1050°C), it is named in term of “temporary expansion”. The temporary expansion is observable only for the sample containing limestone much more than 10.5% and increases its intensity with increasing amount of limestone added. The sample containing 15% of the fine limestone (content of particles smaller then 10μ in size, 83%) has no expansion, but a little shrinkage in the temperature range corresponding to the temporary expansion. When the coarse limestone (content of particles smaller than 10μ in size, 40%) is used, however, the sample has temporary expansion in a great extent.Furthermore, identification of minerals newly formed in the green bodies by heating was made by means of D. T. A. and X-ray analysis with the results that they were the calcia-containing minerals such as gehlenite, wollastonite and anorthite. On the other hand, the mixtures corresponding to gehlenite, wollastonite and anorthite in chemical composition was prepared in advantage of limestone, quartzite, alumina and china clay. They were submitted to dilatometry in order to compare with the limestone containing green bodies.Discussion of these experimental results leads to the conclusion that the temporary expansion observable for the green bodies containing limestone is attributed to formation of calcium compounds such as gehlenite and wollastonite.
- 社団法人日本セラミックス協会の論文
- 1971-05-01