The effect of neutron-irradiation on the shear properties of SiC/SiC composites with varied interface

The materials used in this study were unidirectional Hi-NicalonTM SiC fibers reinforced SiC matrix composites. SiC/SiC composites were fabricated by chemical vapor infiltration (CVI) method. Fibers were coated with either pyrolytic carbon, multiple SiC layers or `porousʹ SiC by CVI method prior to matrix deposition. They were irradiated in the High Flux Isotope Reactor at damage level of 0.5 dpa. Irradiation temperatures were either 300°C or 500°C. Interfacial shear properties and mechanical properties were evaluated. The correlation between interfacial shear properties and mechanical properties was examined. The `porousʹ SiC interface showed a strong bond when compared with the pyrolytic C and multiple SiC interface in the non-irradiated state. The interfacial shear properties were substantially degraded by irradiation with the `porousʹ SiC showing the most degradation.