Oxidation behavior of 3D Hi-Nicalon/SiC composite exposed in wet and simulated air environments

► Oxidation behavior of a 3D Hi-Nicalon/SiC was comparatively studied in two environments. ► Morphologies, weight changes and failure behavior of the oxidized composites are different. ► Strength decrease of the oxidized composite is determined by degradation of Hi-Nicalon fiber.