Design of experiment approach for sintering study of nanocrystalline SiC fabricated using plasma pressure compaction

Plasma pressure compaction (P2C) is a novel sintering technique that enables the consolidation of silicon carbide with a nanoscale microstructure at a relatively low temperature. To achieve a high final density with optimized mechanical properties, the effects of various sintering factors pertaining to the temperature-time profile and pressure were characterized. This paper reports a design of experiment approach used to optimize the processing for a 100 nm SiC powder focused on four sintering factors: temperature, time, pressure, and heating rate. Response variables included the density and mechanical properties. A L9 orthogonal array approach that includes the signal-to-noise (S/N) ratio and analysis of variance (ANOVA) was employed to optimize the processing factors. All of the sintering factors have significant effect on the density and mechanical properties. A final density of 98.1% was achieved with a temperature of 1600?C, hold time of 30 min, pressure of 50 MPa, and heating rate of 100?C/min. The hardness reached 18.4 GPa with a fracture toughness of 4.6 MPa?m, and these are comparable to reports from prior studies using higher consolidation temperatures.