Design, Construction and Performance of Silicon Nitride Tool Parts in Steel Thixoforming

Abstract

The design and performance of silicon nitride (Si3N4) dies for the semi-solid processing of steels is studied by the example of a punch and a lower swage in upset forging. The observed failure mechanisms and degradation effects are related to short-term effects resulting from mechanical and thermal loads and long-term effects owing to chemical and tribological attack. Results show that well-defined process conditions (cycle time, solidification time in the die) and a ceramic-suitable design are a pre-requisite for reliability and sufficient service life of ceramic dies.