Leak rate performance of three silicone elastomer compounds after ground-simulated and on-orbit environment exposures
Christopher, Daniels, et al. (2011). "Leak rate performance of three silicone elastomer compounds after ground-simulated and on-orbit environment exposures." 3rd AIAA Atmospheric Space Environments Conference
Three silicone elastomer compounds were evaluated to determine the effect of exposure to a spacecraft’s external environment and of exposure to atomic oxygen in terrestrial facilities. Air leak rate was used as the metric to quantify the degradation that occurred on S0383-70, S0899-50, and XELA-SA-401 elastomers formed into O-rings. Specimens were positioned external to the International Space Station (ISS) for 18 months aboard MISSE-6 where they were exposed to atomic oxygen, ultraviolet and particle radiation, vacuum pressure, and temperature fluctuations. The flight specimens were separated into two groups and positioned in ram-facing and in wake-facing directions, where the atomic oxygen fluence was 1.2×1022 and 6.0×1020 atoms/in2, respectively. Select specimens were pretreated with atomic oxygen generated by introducing air to radio frequency plasma. Yet another set of specimens was reserved as a control group to which the other were compared. The leak rates of the specimens were determined using a mass-point leak rate technique with uncertainty analysis and showed that the performances of the three elastomers degraded at different rates. The leak rate of XELA-SA-401 was eliminated from the study due to its poor relative flight performance. The ratio of the ram-facing to wake-facing leak rate was 1.2 and 2.9 for the S0383-70 and S0899-50 compounds, respectively, indicating the former compound was not appreciable affected by atomic oxygen while the later was. After receiving atomic oxygen fluency of 1.2×1022 atoms/in2 during flight, the leak rate of the S0899-50 was 5 times that of the S0383-70 specimens; however, the leak rate of the S0383-70.
DOI: doi:10.2514/6.2011-3823 10.2514/6.2011-3823