Damage behavior of atomic oxygen on a hafnium carbide-modified C/SiC composite

Capability of a HfC-modified C/SiC (C/SiC-HfC) composite against high-speed atomic oxygen (AO) atoms was evaluated in a ground-based low Earth orbit simulating system. Energy Dispersive Spectrum, Scanning Electron Microscopy, X-Ray Diffraction and Raman spectroscopy were employeed to investigate the damage behaviors of the material. The results show that HfC was oxided by AO preferentially, while HfO₂ and graphite films were its main products during AO exposure. The crystallization degree of the graphite film increased with the increasing of AO total flux. It's found that SiC areas had lower surface damage than HfC areas, and SiO₂ was its main reacting product. Ascribed to the evolution of surface craters, three-point bending strength of the specimens increased within the first 10 h exposure of AO and decreased thereafter. The damage mechanisms of AO over C/SiC-HfC were revealed also.