Gelcasting of Aluminum Nitride Ceramics

Aluminum nitride (AlN) ceramics has been prepared by nonaqueous gelcasting in air and sintering in nitrogen atmosphere. The influence of pH and dispersant on the ζ potential of AlN–ethanol slurry was studied. And the rheological behavior of the slurry was evaluated to optimize the dispersant content and solid loading. Concentrated AlN slurry (53.8 vol%) with low viscosity was prepared using polyethyleneimine as the dispersant. Sorbitol polyglycidyl ether and tetraethylenepentamine were used as gelling and hardening agents, respectively. A green body with a relative density of 63.3% was obtained. After sintering at 1800°C for 4 h, AlN ceramics with a relative density of 99.6% and a thermal conductivity of 200 W·(m·K) −1 were produced.