Thermal analysis of advanced ceramic coating on carbon/carbon substrates for aerospace re-entry re-usable structures

Aim of the work is to describe a novel coating process based on the Al-Oxide ceramic varnish ‘Pyropaint’ applied on a spacecraft Thermal Protection System for re-entry application. The proposed treatment is intended to preserve the thermo-mechanical properties of a Carbon/Carbon substrate from the detrimental space environment conditions, such as LEO thermal cycles, outgassing due to ultra-high vacuum, and Atomic Oxygen / UV irradiation. In order to enhance the coating performance, the used varnish is enriched with Si-Oxide nanoparticles in different weight percentage. The first step is to analyze the coefficient of thermal expansion (CTE) by dilatometric measurement in order to evaluate the thermal stress of both substrate and coating layer at high temperatures. Particular emphasis is devoted to study the effect of the coating/substrate adhesion, which may result in anomalous mechanical behavior. After thermal conditioning, the several specimens under test are investigated by full microscopy analysis using SEM/EDX techniques, then the experimental results are compared each other. The present study paves the way for the future development of advanced structural spacecraft panels as well as of re-usable re-entry systems.