CREEP BEHAVIOR OF COMPOSITIONALLY VARIED Si/SiC COMPOSITES

摘要

The creep behavior of Si/SiC composites containing 10 to 45 vol percent Si was investigated. These composites were fabricated using reactive infiltration of molten Si into porous preforms consisting of carbon whiskers and particles as well as SiC particles. Creep deformation was measured using four-point bend tests at temperatures from 1250 to 1550 deg C and stresses from 60 to 400 MPa. The creep rate was observed to increase with increasing Si content. This increase was particularly sharp in the composites where Si formed a continuous network. Si/SiC composites containing 20 vol percent Si and less exhibit excellent creep resistance up to 1550 deg C. Creep rates as low as 10~(-10) to 10~(-9)/s were obtained at stresses of 40 to 75 percent of strengths.