a kmergia@ipta.demokritos.gr, b Volker.Liedtke@arcs.ac.at , c tspeliotis@ims.demokritos.gr, d gapost@ipta.demokritos.gr, e spyros@ipta.demokritos.gr Abstract. The use of ceramic composite materials in aerospace applications requires the development of oxidization protection coatings which can withstand very high temperatures. HfO 2 is a promising material as a high temperature oxidization protective layer. HfO 2 coatings have been deposited by radiation frequency magnetron sputtering all over

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... e surface of SiC substrates and were tested under re-entry conditions. Also their oxidization resistance in air in the temperature range 1100 to 1450°C has been examined. The coatings were found to be stable and well-adhering to the substrate even after 100 re-entry cycles. No oxidization of the underlying SiC structure is observed. Re-entry and oxidization tests result in the formation of HfSiO 4 at the HfO 2 /SiC interface, which further promotes their oxidization resistance.