Highly concentrated aqueous SiC slurry containing fine SiC powder: A new approach for ultra‐dense green body

Abstract

AbstractSiC slurry with ultra‐high concentration up to 70 vol% was prepared using oxidized fine and coarse SiC powder mixture, and dense SiC green body with a relative density of 76% was fabricated by drying the slurry at ambient condition. Three approaches were performed to prepare highly concentrated SiC slurry; preparation of SiC powder having good dispersion behavior, optimization of the oxidation condition, and optimization of bi‐modal particle size distribution. An aqueous slurry with the solid loading up to 62 vol% could be prepared using fine (150 nm) SiC powder prepared by the mechanical alloying of Si and carbon. The surface property of the fine and coarse (10 μm) SiC powders was optimized using an oxidation treatment. The maximum solid loading of the fine SiC slurry prepared using oxidized powder was 66 vol%. By optimizing the mixing ratio of the oxidized fine and coarse SiC powder to 75:25, the solid loading of the SiC slurry could increase up to 70 vol%. The relative densities of the green bodies after drying 66, 68, and 70 vol% slurries were 69, 75.7, and 76.1%, respectively, which values were higher than those (58%) prepared by cold isostatic pressing under 200 MPa.