COMPOUNDING CERAMIC POWDERS PRIOR TO INJECTION MOULDING.

The fabrication of complex engineering ceramic shapes of high dimensional accuracy and uniform strength can be achieved by slip casting and injection moulding. Injection moulding offers automated production and allows greater versatility of form in component design. In order to fill a mould cavity the ceramic powder should be incorporated into an organic vehicle which confers fluidity. At this early stage in the process poor dispersion of powder and the survival of agglomeration can have an irreparable influence on the final ceramic microstructure and uniformity of shrinkage. The use of a twin screw extruder developed for heavily filled organic polymers and now applied to ceramic engineering is described. The quality of dispersion is compared with other ceramic fabrication routes.