INFLUENCE OF SLIP RHEOLOGY ON PRESSURE CASTING OF ALUMINA

Pressure slip casting has been developed more intensively since it can produce near net-shaped green bodies with shorter processing cycles. As with the other colloidal forming techniques, the preparation and co ntrol of stable, well-dispersed ceramic slips is considered en a key p arameter. In this study a series of alumina slips containing different kinds of dispersants including potential determining ions, counterion s or electrosteric forms, were prepared. According to the shear stress /shear rate relationships, the slips were found to behave very differe ntly, showing Newtonian, plastic, pseudoplastic or thixotropic behavio ur. The slips were cast at a pressure of 3 . 4 MPa and the highest den sities were obtained if Newtonian slips without or with only slight th ixotropy were cast. The cast bodies produced with slips of plastic and /or strongly thixotropic behaviour did not reach the required density nor wet cast consistency. (C) 1996 Elsevier Science Limited.