Processing and microstructure characterization of liquid-phase-sintered, α-SiC matrix composites

Dense silicon carbide (SiC)-based ceramics were obtained by hot-pressing using BaAl2Si2O8 (BAS) as an additive. The results showed that BAS could serve as an effective liquid sintering aid to promote densification and facilitate the growth of SiC grains. The relative densities, flexural strength and fracture toughness of the composites increase with increasing the BAS content. The flexural strength and fracture toughness of 40 wt%BAS/SiC composite could reach 510 MPa and 7.0 MPa m(1/2), respectively, The main toughening mechanisms are crack deflection, crack bridging and SiC grain pullout. The complete crystallization of BAS is beneficial to the high temperature mechanical properties and the obtained 40 wt%BAS/SiC composite ;could maintain the room strength up to 1200 degrees C. (C) 2009 Elsevier B.V. All rights reserved.