Densification of SiC from Amorphous Polysilazane with The Addition of β-SiC as a Filler Prepared by Hot Pressing Furnace

Abstract

Dense silicon carbide (SiC) was successfully sintered from amorphous polysilazane (PSZ) using hot pressing at 1750oC for 1 hour under an applied pressure of 20 MPa in Ar atmosphere. The effect of β-SiC powder as a filler on the density, phase, micro structure and hardness were examined. Al2O3 and Y2O3 were used as sintering additives through the liquid phase sintering mechanism. The phase analysis showed the formation of SiC after sintering of amorphous PSZ. However, α-SiC was a dominant phase and the amount of α-SiC decreased with the addition of β-SiC powder. The relative density of sintered SiC was obtained in range 99.6 -99.7% regardless of the addition of β-SiC powder. Sintered SiC from amorphous PSZ revealed significant shrinkage compared to sintered SiC from β-SiC powder, while the minimum shrinkage was achieved by the addition of 70% β-SiC into amorphous PSZ. However, the hardness of sintered SiC did not correlate with the addition of β-SiC powder, with highest hardness of 26.4 GPa, which is SiC from solely β-SiC powder. This result indicates that amorphous PSZ is an alternative precursor to fabricate dense SiC.