コロイド混合法により調製したムライト前駆体微粒子の液中ヘテロ凝集構造の解析

概要

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To control the hetero-coagulation structure of ultra-fine γ-Al_2O_3 and SiO_2 powders for mullite ceramics, hetero-coagulation structures under different pH conditions were investigated by focusing on electrophoretic mobility and aggregate size distribution in suspensions. A bimodal electrophoretic mobility distribution was observed when precursor powders were prepared by colloidal mixing processes at pH=9.5. Since each peak almost corresponded to the electrophoretic mobility of γ-Al_2O_3 and SiO_2 particles, heterocoagulates were not formed in the suspension. In the case of pH=6.0, weak hetero-coagulates were generated in suspension. However, uniform mixing could not be attained and large coagulates were formed. On the other hand, narrow and single mode electrophoretic mobility distribution was observed after colloidal mixing at pH=4.4. It is concluded that the uniform hetero-coagulates for mullite precursor with the stoichiometric composition can be obtained. The change in structures of hetero-coagulates with pH conditions was analyzed by DLVO theory. Uniform and fine grained mullite ceramics were prepared from uniformly hetero-coagulated precursor powders mixed at pH=4.4.
社団法人日本セラミックス協会の論文
1998-02-01