Taguchi Method for Sintering Study of Nanocrystalline Silicon Carbide Fabricated using Plasma Pressure Compaction

摘要

Plasma Pressure Compaction is a novel sintering technique that enables the fabrication of silicon carbide samples with nanoscale microstructures at relatively low temperatures. To achieve SiC parts with a high final density and good mechanical properties, the effects of various sintering factors pertaining to the temperature-time profile and sintering pressure have to be characterized and optimized as well. This paper reports the use of Taguchi method in optimizing the process factors for sintering of nanocrystalline SiC powder (average size 100 nm). The effects of four sintering factors: temperature, time, pressure and heating rate on the final density and the mechanical properties of the sintered part were studied. The L_9 orthogonal array, signal to noise ratio and analysis of variance were employed to optimize the various factors and study the contribution of each factor to the output variables. It was found that all the chosen sintering factors have significant effect on the final density and the mechanical properties such as the hardness and the fracture toughness. A fractional final density of 98.1% was achieved with a low sintering temperature of 1600°C, hold time of 30 min, pressure of 50 MPa and heating rate of 100°C/min. The hardness value of 18.4 GPa and the fracture toughness of 4.6 MPa√m were comparable to the values reported in the literature for SiC samples sintered at much higher temperature.