Atomic oxygen effects evaluation on high thickness carbon-carbon nano-coated structures for re-entry applications

Since the beginning of the Space Age, the re-entry environment has been crucial both for manned and unmanned missions. Thus, along with high temperatures and plasma created during the re-entry phase, several issues must be considered in order to use new technologies and materials. Carbon/Carbon composites (C/C) are widely used for high temperatures applications, included Thermal Protection Systems (TPS) for re-entry; thus, the effects of the space environment have to be considered in order to design and produce a re-entry structure that can be used also for long duration missions. In this work, high thickness Carbon/Carbon has been tested in the Atomic Oxygen (AO) Facility at the Aerospace Systems Laboratory (LSA) of Sapienza University of Rome, evaluating the erosion and oxide creation on the TPS surface due to AO interaction. This latter can affect the material and degrade the thermal, physical and mechanical properties of the TPS structure, thus an evaluation of these effects is mandatory. The experimental campaign has been carried out setting the AO generator at a fluence of 8.7×10 20 atoms/cm 2 , for a time of exposure of 3000 equivalent sun hours. The material involved in the campaign is a high thickness Carbon/Carbon made with a customized infiltration process. Two categories of sample have been considered: naked C/C and C/C coated with an Aluminium Oxide varnish charged with 1w% of Silicon di-Oxide nano-spheres.