OPTIMIZATION OF INJECTION-MOLDING PROCESS FOR SILICON-NITRIDE COMPONENTS

The major objective of this study was to develop an optimised process for manufacturing silicon nitride components. The effects of solid con tent, binder type, debinding solvent, and thermal debinding heat profi le were investigated. Injection parameters such as pressure, speed, an d temperature were also investigated and were found to have substantia l influence on the mechanical properties of products. Solvent debindin g before thermal debinding substantially reduced the debinding time th rough the formation of open channels in the binder. A debinding model is proposed based on experimental observations. The defects were consi derably reduced and strength was enhanced by cold isostatic pressing w ithout causing significant dimensional changes in the sintered body. C omplex shaped silicon nitride blades with density 97% of theoretical a nd 880 MN m(-2) in bend strength were made successfully. (C) 1996 The Institute of Materials.