Injection moulding of hollow silicon nitride parts using fusible alloy cores

An interesting method of injection moulding originally developed for the plastic industry, is applied to technical ceramics in order to manufacture complex-shaped hollow parts at a reasonable cost. Silicon nitride parts are moulded on fusible alloy cores that are subsequently removed by melting before the final sintering step. Several parameters are investigated to remove the alloy cores without creating defects. Best results are obtained with a ceramic mixture based on a polyethylene binder phase and by melting the cores using an induction melting method.