Perspectives on Environmental Barrier Coatings (EBCs) Manufactured via Air Plasma Spray (APS) on Ceramic Matrix Composites (CMCs): A Tutorial Paper


There are many sets of information in the literature (e.g., papers, books and websites) about the great achievements that are expected for aerospace gas turbine engines by the employment of ceramic matrix composites (CMCs) and thermally sprayed environmental barrier coatings (EBCs) in their hot zones (e.g., combustion chambers, vanes, shrouds, blades and afterburners). Among these achievements, it is typically highlighted (i) turbine weight reduction, (ii) reduced fuel consumption, (iii) higher operation temperatures, (iv) superior thrust-to-weight ratio and (v) lower emission of toxic gases to the atmosphere. Although these achievements are true, they are generally not well-explained to the reader on how together they come to be. In addition, according to “conventional wisdom”, some of these engineering feats are in fact opposing each other (e.g., higher operation temperatures versus lower emissions). The objective of this tutorial paper is to present the reader how these feats are achieved by the concomitant combination of imaginative engineering. It will explain the non-stop driving force for increasing combustion temperatures; show the basic concepts of CMCs, the paramount need of EBCs, and the complexity of creating EBC architectures via air plasma spray (APS). Finally, highlights on how EBCs/CMCs are tested at high temperature will be provided. The content of this paper shall be understood by anyone with basic knowledge in materials processing and surface engineering.

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Fig. 1
Fig. 2

Adapted from Padture (Ref 2) and Clarke et al (Ref 11). (b) Combustion temperature as a function of the specific core power of a gas turbine (inverted plot)—adapted from Perepezko (Ref 13)

Fig. 3

Adapted from Leonard and Stegmaier (Ref 17)

Fig. 4

Source: Ref. 21

Fig. 5

Source: Ref. 44

Fig. 6

Source: Ref. 21


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Correspondence to Rogerio S. Lima.

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This article is an invited paper. The authors were invited based on their experience, knowledge, and expertise in this area to provide expert perspectives on a subject relevant to thermal spray. The views expressed in the paper are those of the author(s).

Dr Dongming Zhu passed away May 30, 2018.

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Lee, K.N., Zhu, D. & Lima, R.S. Perspectives on Environmental Barrier Coatings (EBCs) Manufactured via Air Plasma Spray (APS) on Ceramic Matrix Composites (CMCs): A Tutorial Paper. J Therm Spray Tech (2021).

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  • air plasma spray (APS)
  • ceramic matrix composites (CMCs)
  • environmental barrier coatings (EBCs)
  • gas turbine engines
  • oxide-oxide CMC
  • SiC/SiC CMC