Dispersion of Si3N4 Powders in Tert-Butyl Alcohol

A high molecular weight block copolymer dispersant with pigment affinic groups — DISPERBYK163 (BYK163) was chosen to disperse submicron-sized Si3N4 in tert-butyl alcohol (TBA) solvent. The stability of Si3N4 powders in TBA with dispersant BYK163 was studied by sedimentation. To achieve good casting behavior, rheological measurement was employed to find a reasonable dispersant content in the slurry. The adsorption isotherm of BYK163 on Si3N4particles surface was obtained by thermogravimetric analysis (TGA). Based on the surface chemical properties of Si3N4particles, the dispersing phenomena and mechanism of BYK163 in TBA were summarized. BYK163 could form a steric layer on the surface of Si3N4particles, and effectively prevent particles agglomeration. Therefore, porous Si3N4samples with porosity of 40% to 80% could be prepared from Si3N4slurries with low and high solid loadings due to well dispersion with BYK163 addition.