Ultra-high temperature oxidation protection coatings: Alloying of transition metal borides

Abstract

Surface protection of highly stressed components used in aviation or energy production is of great interest, especially to extend the operation ranges in oxidative environments at extremely high temperatures. Here, transition metal ceramics are a suitable class to resist such conditions. Therefore, we developed alloying strategies, starting from the oxide scale formation of the binary systems – such as HfB2-z, TaB2-z, and WB2-z, which tremendously enhance the oxidation resistance of these coating materials and enable temperature regimes up to 1600 °C. The coating materials were deposited using an unbalanced magnetron sputtering system and consequently oxidized in a DTA/TG setup (using coatings on substrates) to study the oxidation kinetics. We furthermore conducted long-term oxidation tests at 1200 °C for various time periods up to 60 h and applied a broad set of high-resolution characterization techniques (e.g. HR-TEM, APT, SIMS, as well as XRD).