Oxidation and emissivity of Invar 36 alloy in air plasma at high temperatures

To mitigate debris in orbit and to avoid dramatic collisions on Earth after atmospheric re-entry at the end of a spacecraft's life, spacecraft missions have to take into account the influence of the environment (air plasma, high temperature and low pressure) on spacecraft survivability. Therefore, oxidation in air plasma conditions was studied on Invar 36 alloy, which is frequently used for large satellite components, in order to obtain oxidation kinetic laws at high temperature and for a short time duration (a few minutes). Emissivity measurements at high temperatures were also conducted on the virgin alloy - in a high vacuum - and on the oxidized samples in air plasma and under standard air conditions. A significant increase in the total emissivity due to the presence of oxides on the surfaces by a factor of 4 was obtained compared to the non-oxidized surface. An important impact of oxidation in the air on emissivity was observed by different characterization techniques, such as scanning electron microscopy (SEM), 3D profilometry, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). (c) 2018 Elsevier B.V. All rights reserved.