Gelcasting of alumina and zirconia using chitosan gels

A new gelcasting system has been analysed. The gel forming system is based on a solution of 1% chitosan in diluted acetic acid and reaction with glutaraldehyde. An Al2O3 powder-loading rate of 50 vol.% was achieved under optimised conditions. Advantages of this new system include the use of a biopolymer (chitosan), possibility of air drying of green parts, possibility of gelcasting at ambient temperature, and versatility of the process by changing process parameters leading to well specified reaction times. The effect of process parameters on reaction time, slurry properties, and green part properties are presented. Slurries prepared from ZrO2 powders were not fluid. However, dense green parts could still be obtained by transferring these slurries to a mould and drying.