Preparation and properties of BAS/SiC complex phase ceramic materials

Abstract

Celsian was synthesized in situ and was used to sinter silicon carbide. The low temperature pressureless liquid sintering process for BAS/SiC complex phase ceramics was studied, and ceramic materials with high density were prepared. The effect of sintering temperature and content of BAS on density, structure and mechanical properties of the ceramics were investigated. The densification and microstructures of BAS/SiC ceramics were observed by scanning electron microscope. The crystalline phase of the composite ceramics was identified by X-ray powder diffraction. The results show that celsian is synthesized at the temperature of 1800 ℃, and BAS/SiC ceramics are prepared with density of 3.2 g/cm3. BAS is precipitated in hexagonal structure, and SiC particles are distributed uniformly in the composite ceramic. The flexural strength and fracture toughness of composite ceramics are decreased due to grains growth while the sintering temperature is above 1800 ℃. When the mass content of BAS reaches 30%, the typical flexural strength, elastic modulus and fracture toughness of the pressureless sintered BAS/SiC ceramics are 413 MPa, 210 GPa and 5.03 MPa?m1/2 at room temperature.

Keywords

• celsian
• silicon carbide
• pressureless sintering
• mechanical properties