Performance evaluation of dispersibility of submicron powder by jet mill and clarification of dispersion mechanism by addition of aid

Abstract

This study investigates the challenging task of powder dispersion consisting of primary particle with nanometer size range in jet milling, with an emphasis on the impact of the pre-processing, particularly influence of the various dispersion aids addition. The primary objective was to elucidate the dispersion mechanisms involved when dispersion aids are added and how different aids affect dispersibility. The experiment included the evaluation of dispersibility in a spiral jet mill (SJM) and ejector without aids with three types of the raw material powders: SiO₂, coarse Al₂O₃, and fine Al₂O₃. The experiment revealed that the SJM exhibits aligning the particle size distribution closely with that of primary particles. Subsequently, the dispersibilities of SiO₂ powder in a SJM with adding three different aids, diethylene glycol monomethyl ether (DEGME), diethylene glycol (DEG), and water were measured. It demonstrates that DEGME was found to be more effective and stable than DEG, leading to higher dispersibility at certain concentrations. Further shape factor analysis for the pre-processed powder established the model for the aids-induced dispersion process, suggesting the formation of coarser aggregates with concavities, facilitating the detachment of particles from the edges of aggregates as the aid evaporates during the milling process. These insights offer valuable contributions to nanoparticle dispersion, a critical aspect in improving the quality of nanoparticle-layered products in various powder technology industrial applications.