The degradation behavior of C/C composites in high-energy atomic oxygen

In low earth orbit (LEO), spacecraft, space structure and other applications encounter a degradation problem induced by the impact of atomic oxygen (AO) in the space environment. C/C composites (C/Cs), which are widely applied to different applications in space systems, were tested to study the irradiation and bombardment effects of LEO space environment on the composites. The degradation was analyzed in the aspect of mass loss, morphology and flexural strength and thermal conductivity properties. Results show that the specimens are bombarded by high-speed AO with high activity during AO irradiation test. The flexural strength of C/C composites after AO irradiation test for 24 h (AO24, 150.4 MPa) is decreased by 25.8% than C/Cs (202.7 MPa). The coefficients of thermal conductivity of C/Cs after AO irradiation show an increase. Carbon fibers and pyrolytic carbon (PyC) were also exposed to AO irradiation test. Results show that the denudation rate of PyC is slower than that of C/C composites and carbon fiber. Besides, the denudation of carbon fiber (form crisscrossed ravine) is most serious. PyC shows the least damage. This work may provide not only the influence of AO irradiation on C/Cs but the protection of C/Cs from AO irradiation.