Spark plasma sintering: A powerful tool to develop new silicon nitride-based materials

Abstract

Several key topics on the current assisted sintering of Si 3N 4-based materials are reviewed. First, different proposed mechanisms for spark plasma sintered (SPSed) ceramics are presented, discussing the electric field effect on the liquid phase behaviour and how it may influence the liquid phase sintering of Si 3N 4 ceramics. Next, we show that the SPS is a powerful tool to develop new Si 3N 4-based materials with tailored microstructures, such as functionally graded materials (FGMs) and carbon nanotubes (CNTs) containing Si 3N 4 matrix composites. Si 3N 4 FGMs are fabricated from a sole homogenous Si 3N 4 mixture just modifying the SPS system punches set-up, thus creating a temperature gradient through the specimen. Finally, the capability of SPS to get dense Si 3N 4/CNTs composites overcoming both constraint densification and nanotubes degradation is proved.