Thermo-mechanical Testing of Oxidation Protection System for Re-entry Applications

I. Huertas Olivares (Sp), V. Liedtke, M. Langer, ARC Seibersdorf Research GmbH (Austria); U. Trabandt, EADS-SI, Bremen (Germany); K. Handrick, MAN Technology AG, Augsburg (Germany) 
 
Carbon fibre reinforced silicon carbide (C/SiC) has a considerable potential for future reusable spacecraft, Thermal Protection Systems (TPS) and others structures which are exposed to high temperatures. C/SiC composites combine excellent thermo-mechanical properties with low weight and high strength for temperatures up to 2000°C. For these systems the C/SiC TPS and hot structure components need to have an Oxidation Protection System (OPS) to prevent the carbon fibre from oxidation during the re-entry phase, where temperatures higher than 1550°C can be reached. The OPS has to ensure full protection of the bulk material over the entire temperature range from 400°C to the maximum temperature despite of the thermal mismatch between coating and bulk material.
Different companies have already developed multi-layer OPS, partially with self healing ability, which have been tested successfully in several TPS plasma tests and in thermo-mechanical cycling investigations. These self healing OPS consist on various layers with different functions: a bonding layer, an intermediate functional layer system with self healing capability and an erosion protection layer. Most of the OPS currently available are manufactured by costly and time-consuming processes and are applied either by slurry technique or by multilayer chemical vapour deposition (CVD) steps.
A novel manufacturing route is based on a fast sol-gel process, allowing rapid and cost efficient application of the OPS.
In this work, nine OPS manufactured by different routes were applied on two C/SiC base materials. The testing was focused at thermo-mechanical tests under re-entry relevant conditions (temperature, temperature gradient, gas pressure) in ARCS’ re-entry simulation chamber and on tests in a plasma wind tunnel.
The influence of test conditions on mechanical properties of the composites and on microstructure of the OPS is depicted.