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 zeta 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 degrees C for 4 h, AlN ceramics with a relative density of 99.6% and a thermal conductivity of 200 W center dot(m center dot K)-1 were produced.