The effect of high dose/high temperature irradiation on high purity fibers and their silicon carbide composites

Silicon carbide composites were fabricated by chemical vapor infiltration method using high purity fiber, Hi-Nicalon Type-S and Tyranno SA, and non-high purity fiber Hi-Nicalon. Bare fibers, SiC/SiC composites and CVD SiC were irradiated at 7.7 dpa and 800 degreesC or 6.0 dpa and 300 degreesC. The density of fiber and CVD SiC was measured by gradient column technique. Mechanical properties of the composites were evaluated by four-point flexural tests. Fracture surfaces were observed by SEM. Tyranno SA fiber and CVD SiC showed similar swelling behavior following irradiation at 7.7 dpa and 800 degreesC. Mechanical properties of composites reinforced with Hi-Nicalon Type-S and Tyranno SA fibers were stable even following neutron irradiation at 7.7 dpa and 800 degreesC. Fracture surfaces of these composites following irradiation were similar to those of non-irradiated composites with relatively short fiber pull-out. (C) 2002 Elsevier Science B.V. All rights reserved.