Effects of SiC whisker addition on mechanical, thermal, and permeability properties of porous silica-bonded SiC ceramics

摘要

The effects of SiC whisker addition into nano-SiC powder-carbon black template mixture on flexural strength, thermal conductivity, and specific flow rate of porous silica-bonded SiC ceramics were investigated. The flexural strength of 1200 degrees C-sintered porous silica-bonded SiC ceramics increased from 9.5 MPa to 12.8 MPa with the addition of 33 wt SiC whisker because the SiC whiskers acted as a reinforcement in porous silica-bonded SiC ceramics. The thermal conductivity of 1200 degrees C-sintered porous silica-bonded SiC ceramics monotonically increased from 0.360 Wm(-1)K(-1) to 1.415 Wm(-1)K(-1) as the SiC whisker content increased from 0 to 100 wt because of the easy heat conduction path provided by SiC whiskers with a high aspect ratio. The specific flow rate of 1200 degrees C-sintered porous SiC ceramics increased by two orders of magnitude as the SiC whisker content increased from 0 to 100 wt. These results were primarily attributed to an increase in pore size from 125 nm to 565 nm and secondarily an increase in porosity from 49.9 to 63.6. In summary, the addition of 33 wt SiC whisker increased the flexural strength, thermal conductivity, and specific flow rate of porous silica-bonded SiC ceramics by 35, 133, and 266, respectively.