Processing Study of Injection Molding of Silicon Nitride for Engine Applications

Silicon nitride is a high temperature structural material currently considered for gas turbine engine applications. Due to the high cost of machining ceramics, net (or near net) shape forming capability of this new high performance material is the key to the ultimate use of this material in engines. Injection molding is one of the most promising forming processes being considered.

The integrity and properties of an injection molded Si₃N₄ part strongly depend on the processing parameters used. To successfully fabricate reliable high performance parts, it is essential to understand the interrelationships between processing variables and the resulting microstructure and properties of the finished parts. This paper summarizes some of the initial results from an on-going NASA funded program to improve Si₃N₄ materials (NASA Contract No. NAS3-24385). The quality of injection molded test bars at various stages of processing will be correlated with selected processing variables.