Spark plasma sintered silicon carbide ceramics with nanostructured ferritic alloy as sintering aid

Nanostructured ferritic alloy-silicon carbide composites (NFA-SiC) were sintered at 1950-2100 °C by spark plasma sintering (SPS). The influence of NFA addition on the sintered NFA-SiC composites has been investigated based on densification, phase, microstructure, and mechanical property. Addition of 2.5 vol% NFA can lead to full densification for the NFA-SiC composites even though it also introduces secondary carbon-rich and iron-rich phases. With the increase of the sintering temperature, the Vickers hardness for the pure SiC and NFA-SiC composite samples is enhanced. However, the NFA-SiC composites have lower hardness than the pure SiC samples. The flexural strength for the pure SiC is also higher than that of the NFA-SiC composites. Nanohardness results demonstrate that the reaction products between SiC and NFA lower the mechanical properties of the NFA-SiC samples.