Mechanical properties of nano-grain SiO2 glass prepared by spark plasma sintering

Silicon carbide (SiC) layers were deposited on silica (SiO2) glass powder by rotary chemical vapor deposition (RCVD) to form SiO2 glass (core)/SiC (shell) powder; this powder was consolidated by spark plasma sintering (SPS). SiO2 glass powder with a particle size of 250 nm was coated with 5-10-nm-thick SiC layers. The resultant SiO2 glass (core)/SiC (shell) powder was consolidated to form a nano-grain SiO2 glass composite at a relative density above 90% by SPS in the sintering temperature range of 1573-1823 K. The Vickers hardness and fracture toughness of the SiO2 glass composite at 1723 K were found to be 14.2 GPa and 5.4 MPa m1/2, respectively.