アルギン酸ナトリウムを用いたアルミナ‐シリカ系ファイバーの合成

Abstract

Ceramic fibers are widely used in refractory furnaces as a low thermal conducting, heat-insulating material and in FRM as a high Young's modulus material. Most of ceramic fibers for such applications have alumina-silica compositions with various alumina/silica ratios. In the present work, alumina-silica fibers were synthesized by a new processs using sodium alginate.Sodium alginate forms viscous solutions and gels at the present of Ca2+ or other divalent and trivalent metal ions, which facilitates the preparation of fibrous gels of metal alginate. The heattreatment of the product at high temperatures gives ceramic fibers of metal oxide.This “sodium alginate method” is a promising one for the industrial purpose, since the spinning of metal alginate is simple and the spinning condition is not so restrictive. This process can be extended to other ceramic fibers, for example, spinel, magnesia and zinc oxide fibers. This method would be also applied to the formation of ceramic thin films.The present paper describes the details of the synthesis of alumina-silica fibers. The thermal transformation of the produced metal alginate and its chemical structure were examined by using X-ray diffraction, DTA, TG, IR measurement etc. The role of chromium oxide added in suppressing the crystal growth of mullite in the alumina-silica fiber was also examined in order to avoid the deterioration in strength.