Thermal and corrosion properties of silicon nitride for copper die casting components

Due to the high melting temperature of copper and copper alloys, conventional die-steel components used in pressure die casting these materials exhibit short service lifetimes and undergo thermal fatigue. Thermal and corrosion properties of silicon nitride were studied to assess the material's applicability in substituting conventional die-steels in casting copper and copper alloys. In this study, experiments were conducted to test the thermal shock resistance and corrosion behaviour of a commercial silicon nitride in contact with molten pure copper. The results did not indicate any corrosive reaction between silicon nitride and pure copper. However, the presence of copper oxides at high temperatures accelerated the oxidation of the ceramic resulting in considerable loss of material. The thermal shock behaviour of silicon nitride proved to be adequate for the application.