超臨界乾燥法を用いたモノリシックシリカゲル体の作製と熱的特性

概要

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Monolithic silica gels without cracking were prepared by supercritical drying of methanol from a homogeneous mixture of tetramethyl orthosilicate (TMOS)-methanol (MeOH)-water (H_2O) system. The preparation of monolithic silica gel was highly effected by H_2O/TMOS ratio in the hydrolyzed solution. Monolithic silica gels were composed of fine particles containing SiOH-groups. They contained many open pores, which was confirmed by N_2 gas permeation experiments. These gels vitrified at 1100℃. The volatile matters in the monolithic gel were eliminated through open pores by firing, and the densification of the gel took place by dehydration of SiOH-groups, where a volumetric shrinkage of about 60% was accompanied on firing at 1100℃. Finally the monolithic silica bulk became silica glass in structure by densification. The obtained silica bulk was optically transparent without cracks or bubbles.
東海大学の論文