Aluminum nitride shaping by non-aqueous gelcasting of low-viscosity and high solid-loading slurry

Abstract

Aluminum nitride (AlN) ceramics has been prepared by a modified non-aqueous gelcasting technique, and the ceramic slurries with low viscosity and high solid loading were obtained by using 1-methyl-2-pyrrolidinone as solvent and Solsperse® 24,000 as dispersant. The rheological behaviors of the AlN ceramic slurry and the densities of AlN ceramics were studied. Typically, the AlN ceramic slurry (Solsperse® 24,000 of 0.5wt% and solid loading of 50vol%) showed a viscosity of 0.09Pa·s at shear rate of 100s−1. And more interestingly, when increasing solid loading to 55vol%, the AlN slurry still kept a low viscosity of about 0.28Pa·s, which was reduced by 30% compared to the reported values. As a result, the resultant green body exhibited a relative density of 65.5%, and a flexural strength of 42.3MPa. After sintering at 1900°C for 5h, the AlN ceramics with an improved relative density of 99.4% was produced. Thus, this research would provide a new way to prepare low-viscosity and high solid-loading AlN slurry.