Creep of mullite composites containing zirconia and silicon carbide whiskers

The compressive creep rate of alkoxide-derived mullite and mullite-zirconia-SiC whiskers was measured at constant stress (50 MPa) and from 1290 to 1481{degrees}C. These composites were made by sol-gel methods, and hot pressed. The creep rate of the composite was about ten times slower than that of the material without the fibers. TEM micrographs of the composite after creep showed debonding and microcracks in the mullite matrix that did not pass through the SiC whiskers. The lower creep rate of the composite can be attributed to the blocking of the microcracks and possibly to the higher elastic modulus of the SiC as compared to the mullite.