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Ultra-high temperature ceramics (UHTCs) are materials defined as having melting points over 3000 °C and withstand temperatures beyond 2000 °C without losing functionality. As service environments become even more extreme, such materials will be needed for the next generation of aeronautic vehicles. Whether it is atmospheric re-entry or sustained hypersonic flight, materials with resistance to extreme temperature will be in demand. Due to the size and shape limitations encountered by current processing methods of bulk UHTCs research of UHTC coatings, specifically thermal spray UHTC coatings, is accelerating. This paper first presents a general summary of UHTC properties, followed by a comprehensive summary of the processing routes and microstructures of current UHTC thermal spray coatings. Then, a detailed review of the oxidation and ablation resistance of UHTC thermal spray coatings is outlined. Finally, potential avenues for the development of new UHTC coating compositions are explored. [ABSTRACT FROM AUTHOR]

The original article can be found online at https://doi.org/10.1007/s11666-022-01381-5. Correction to: J Therm Spray Tech https://doi.org/10.1007/s11666-022-01381-5 When originally published, the author list contained an incorrect initial for the fourth listed author. [Extracted from the article]

Diffusional approaches for fabrication of multilayered Ru-modified bond coats (BCs) for thermal barrier coatings (TBCs) have been developed via Ion'-activity (LA) chemical vapor deposition and high-activity, (HA) pack aluminization. Both processes yield BCs comprising two distinct B2 layers. based on NiAl and RuAl however, the position of these layers relative to the BC surface is reversed when switching processes. The structural evolution of each coating at various stages of the fabrication process and subsequent cyclic oxidation is presented, and the relevant interdiffusion and phase equilibria issues are discussed. Evaluation of the oxidation behavior of these Ru modified BC structures reveals that each B2 interlayer arrangement leads to the formation of α-Al2O3 TGO at 1100 °C, but the durability of the TGO is somewhat different and in need of further improvement in both cases. [ABSTRACT FROM AUTHOR]