Control of Porous Materials Structure Based on the Design of Surface Interaction between Fine Particles by Surface Modification

为了制备高性能、高可靠性的陶瓷，在生坯成型之前，必须避免其原始陶瓷浆料中的不规则集料结构。为了控制陶瓷粉末在浆料中的团聚结构，通常添加聚合物分散剂。然而，由于聚合物分散剂吸附在粉末上的机理还不清楚，聚合物分散剂的用量和分子结构(如疏水比)、pH值、反离子浓度以获得最小悬浮液粘度通常是由经验方法决定的。为了阐明聚合物分散剂在致密悬浮液中的作用机理，并用原子力显微镜(AFM)测量了悬浮液的宏观粘度和颗粒之间的微观表面相互作用，选择了含金属氧化物添加剂和不含金属氧化物添加剂的氮化硅和碳化硅作为分散剂。主要研究内容如下：1)颗粒直径对表面硅醇结构、水化力、不同反离子密度下阴离子聚合物分散剂的结构和含量对致密氧化铝悬浮液粘度的影响利用AFM和胶体探针AFM分析聚合物分散剂在不同反离子密度下聚合物分散剂的电位阻作用3)利用AFM和胶体探针AFM4)分析含氧化物添加剂和不含氧化物添加剂的氮化硅致密悬浮液中阴离子聚合物分散剂的行为4)阴离子聚合物分散剂结构和聚集行为对致密碳化硅悬浮液特性和注浆成型绿体结构的影响5)金属氧化物硅胶的微观结构和表面行为的控制

In order to prepare high performance and high reliability ceramics, it is necessary to avoid the irregular aggregate structure in their original ceramic slurries before green compact formation. In order to control the aggregation structure of ceramic powders in slurry, polymer dispersants are generally added. However, since the mechanism of polymer dispersants adsorbed on powder has not been clarified, the amount and molecular structure of polymer dispersant (hydrophobic to hydrophilic ratio, e.g.), pH, counter-ion concentration to obtain the minimum suspension viscosity have been often decided by an empirical approach.In this work the systems of the powder of silica, alumina, silicon nitride with and without metal oxide additives and silicon carbide have been chosen to clarify the action mechanism of polymer dispersant in dense suspension and to correlate the macroscopic suspension viscosity and microscopic surface interaction between particles measured by an atomic force microscopy (AFM).The following topics have been focused :1) Influence of particle diameter on surface silanol structure, hydration force, and aggregation behavior of alkoxide-derived silica particles2) Effect of anionic polymer dispersant structure and content on dense alumina suspension viscosity analyzing with the electrosteric interaction of polymer dispersant by AFM and colloid probe AFM under different counter-ion densities3) Analysis of anionic polymer dispersant behavior in dense silicon nitride suspensions with and without oxide additives by using AFM and colloid probe AFM4) Effect of anionic polymer dispersant structure and aggregation behavior on dense silicon carbide suspension characteristics and slip-casted green body structure5) Control of microstructure and surface behavior of silica gel prepared from metal oxide