火山作用と関係ある無定形ケイ酸の性質とその応用的研究-35-オパ-ル質ケイ石を原料とするケイ酸石灰塩水和物の合成

概要

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Opaline silica rock (94.2% SiO_2) occurs in Iohjima island, Kagoshima Prefecture. A mixture of the silica powder and milk of lime (calcined CaCO_3) was stirred in a teflon container of autoclave and treated hydrothermally under the following conditions; molar ratio of Cao/SiO_2 1.05, weight ratio of water/solid 5 to 30, and temperature 80°-250°C foo 1 to 50 h. Effect of firing temparature of raw silica and CaCO_3, additive of heavy metal ions such as Ni^{2+}, Cr^{3+} and Fe^{3+}, and the condition of reaction on the phase of products and the morphology was examined using the X-ray powder diffraction test (XRD), the differential thermal analysis (DTA), the thermal gravimetric analysis (TGA), the infra-red absorption spectroscopy (IR), and electron microscopy. The results showed that the products treated hydrothermally above l80°C were C-S-H(CaO-SiO_2-H_2O), α-C_2SH(2CaO･SiO_2･H_2O), tobermorite(6CaO･5SiO_2･6H_2O) and xonotlite(6CaO・6SiO_2･H_2O), especially promoted by the addition of Cr^{3+} in tobermorite and promoted with increasing of crystlline silica (cristobalite) by calcination in xonotlite.
鹿児島大学,カゴシマダイガク,Kagoshima Universityの論文