The effect of processing on the properties of silicon carbide
Researcher: Naeem Ur-Rehman
The covalent nature of the bonding in silicon carbide (SiC) limits the atomic mobility and necessitates the use of additives to promote densification. This project is investigating hot pressed and spark plasma sintered SiC with addition of AlN. Earlier work included studying how the AlN distribution changes during processing and how this affects the microstructures and resulting mechanical properties. A range of materials have been produced and characterised using secondary ion mass spectroscopy in a focussed ion beam workstation (FIB-SIMS), by scanning electron microscopy of chemically etched samples, and by transmission electron microscopy.
Currently the investigation is exploring the properties of the different silicon carbide grades. Emphasis in the study is on the response to indentation. For example, the figure shows how the small scale hardness (up to 0.5 N) varies with strain rate.