炭酸カルシウム-カオリン混合物の1000℃以下での反応及び焼結

概要

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Reaction and sintering characteristics of kaolin and CaCO_3 mixtures were investigated using New Zealand kaolin and finely ground calcite powders as starting materials. Depending on the content of CaCO_3, dense ceramics consisting of single phase of anorthite or composite of gehlenite, wollastonite and anorthite were obtained by firing below 1000℃. With the heat processing, CaO reacted with decomposed kaolin from 800 to 850℃ and formed metastable amorphous materials. Thus formed active amorphous materials sintered rapidly between 850 and 950℃ by the viscous flow to form glass-like dense ceramics. According to the increase in amount of CaO, the sintering temperature lowered from 950 to 900℃. With the further heat processing, gehlenite, anorthite and wollastonite instantly crystallized, and the dense polycrystals were obtained. Their thermal expansions could be controlled between 4.5 and 6.5 × 10^<-6>/℃ and the bending strengths were about 200 MPa. Thus obtained alkaline-free silicate ceramics could be utilized as the electrical insulators or the multilayered ceramic substrates.
社団法人日本セラミックス協会の論文
1997-08-01