Consolidation Behavior and Mechanical Properties of SiC with Al₂O₃ and Yb₂O₃ Consolidated by SPS

Abstract

SPS consolidation of β-SiC powder was performed using Yb₂O₃-Al₂O₃ as sintering additives. Densification behavior and mechanical properties of SPS-consolidated SiC were compared with those of hot-pressed SiC. Nearly full densification was attained at about 1750°C for SPS-consolidated SiC and at about 1900°C for hot-pressed SiC, respectively. Both optimal bending strength and fracture toughness of SPS-consolidated SiC were 720MPa and 4.0MPa·m^1/2 and these values were higher than those (640MPa and 3.5MPa·m^1/2) of hot-pressed SiC, indicating that SPS consolidation can improve the bending strength without degradation of fracture toughness. From XRD and Raman scattering analysis, it is suggested that 3C-type disordered structure is preserved in the SPS-consolidated SiC and the improvement of the bending strength without degradation of fracture toughness is attained by the preservation of the 3C-type disordered structure.