Protection of Nb- and Ta-based alloys against high temperature oxidation

Coatings and Thin Films for Spacecraft Thermo‐Optical and Related Functional Applications

“…Ceramic multilayer coatings with high melting temperatures were also investigated during the development programme of ESA's Hermes programme …”

The Oxidation Resistance of Nb-Si-Based Alloys at Intermediate and High Temperatures

“…Recently, alloying elements such as Ti, Cr, Al, Ge, B and rare elements have been added to enhance the oxidation behavior of Nb-Si-based alloys at high temperatures [15][16][17]. With increasing Si concentration, Nb-Si-based alloys show better oxidation performance [13,18].…”

Microstructure and oxidation behavior of in situ formed TaSi2–Si3N4 nanocomposite coating grown on Ta substrate

“…Secondly, the cyclic oxidation resistance of TaSi 2 coating is poor due to the cracking of TaSi 2 coating when subjected to thermal cycling [20][21][22][23][24][25]. This behavior originates from the mismatch of coefficient of thermal expansion (CTE) between TaSi 2 coating (8.9 Â 10 À6 /K) and Ta substrate (6.6 Â 10 À6 /K).…”

“…In other words, coating layer should provide a low viscosity oxide phase during the oxidation that would flow into cracks and provide a self-healing capability. Even though many tantalum silicide coatings modified with manganese, chromium, iron, titanium, molybdenum, tungsten, and/or aluminum have been investigated, the improvement of isothermal and/or cyclic oxidation resistance was not found in the literature since crack-free tantalum silicide base coatings forming an exclusive SiO 2 scale could not be produced [15,16,[20][21][22][23][24][25]. Therefore, aforementioned two inherent problems have to be solved to ensure the maximum lifetime of TaSi 2 coating in air at high temperatures.…”