Mechanical property change and swelling behavior of SiC fiber after light-ion irradiation

Studies on the effects of helium or hydrogen gases on the mechanical properties and size stability of SiC fibers were examined using accelerator implantation techniques. Three types of Nicalon fibers (Nicalon-CG, Hi-Nicalon, and Hi-Nicalon type-S) were examined. Three levels of implanted gas concentrations from 50 to 5000 appm were conducted. Swelling of the fibers was observed after helium implantation. The amount of swelling depended on the helium concentration and the type of fiber. The swelling had vanished after the post-implantation annealing at 1000 °C. The slight decrease of tensile strength was observed after the He implantation. It remained after the post-implantation annealing up to 1400 °C. The significant effects of hydrogen implantation on the strength and swelling were not observed in this work.