カオリナイトとMgOの900℃以下での反応に及ぼすB_2O_3の効果

概要

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Thermal reactions of mixtures of kaolinite and magnesium compounds in the mole ratio of MgO:Al_2O_3:SiO_2=1:1:2 were investigated to obtain uniform amorphous materials containing magnesia below 900℃. B_2O_3-added mixtures of kaolinite and ultrafine particles of synthesized magnesium hydroxide with an average width of about 0.1 μm resulted in the amorphous state at about 800-850℃ after decomposition of the starting materials. Addition of B_2O_3 promoted the crystallization of μ-cordierite from amorphous state and then the crystallization of α-cordierite. Addition of B_2O_3 more than 1 mass% appeared to accelerate the direct crystallization of α-cordierite from the amorphous state. The complete transformation to α-cordierite was obtained by firing at 900℃ for 1h. On the other hand, uniform amorphous materials were not obtained from mixtures of kaolinite and reagent-grade magnesium compounds with an average particle size of about 1 μm by firing at 900℃, because of insufficient diffusion reaction of mixtures.
社団法人日本セラミックス協会の論文
1998-12-01