pH controlled dispersion and slip casting of Si3N4 in aqueous media

[摘要] The dispersion characteristics of commercial Si₃N₄ powder in aqueous media (deionized water) was studied as a function of pH in the range 2â€�??11. The slip was characterized for its dispersion quality by various experimental techniques like particle size analysis, sedimentation phenomena, viscosity and flow behaviour and zeta potential analysis. The optimum dispersion was found to be in the pH region 9â€�??11 wherein the slurry displayed minimum sedimentation height, minimum viscosity, near Newtonian flow behaviour and maximum zeta potential. The slip is highly agglomerated in the pH range 2â€�??8 as manifested by higher sedimentation height, higher viscosity, lower zeta potential and thixotropic non-Newtonian flow behaviour. The 72 wt% (44 vol.%) Si₃N₄ slips made at pH = 10 resulted in green bodies having 53â€�??59% of theoretical density after casting into plaster molds.

[学科分类] 材料工程

[关键词] Dispersion;slip casting;Si3N4 slips.