高分子電解質分散剤の立体配座とマグネシウムイオンがスラリー中粒子への吸着現象に及ぼす影響

摘要

セラミックス湿式成形では，プロセスの最初の工程であるスラリー調製時の粒子集合状態が最終製品の性能に大きな影響を及ぼす。緻密な最終製品を得るためには粒子がよく分散したスラリーが良いとされており，一般的に高分子電解質等の添加剤を添加して粒子集合状態を制御している。しかし，学術的にそのメカニズムが完全に理解されておらず，現場では勘や　経験に頼ってスラリー調製しているのが現状である。%In wet shaping, the amount of dispersant added to the slurry is a crucial factor in producing high-quality ceramic products. Many researchers have investigated the amount of dispersant that adsorbs to slurry particles. However, few studies have examined how the solid concentration of slurry affects the amount of adsorbed dispersant. In our previous work, we measured the amount of adsorbed dispersant at various solid concentrations and addition amounts of dispersant. In the present work, alumina particles containing magnesium as a sintering aid were used. The conformation of polyelectrolyte dispersant was changed by magnesium ions, and the adsorption isotherm showed a local maximum. In the case of laurate, some molecules remained in solution and did not adsorb to particles because of its thermal motion and few adsorbing sites. Consequently, the amount of adsorbed dispersant was affected by the diffusion of magnesium from the particles, the molecular weight of the dispersant, and the solid concentration of the slurry.