Thermal barrier coatings performed by suspension plasma spraying: development and characterization

Aeronautic industries have developed over many years thermal barrier coatings (TBC) to protect the metal super alloys of gas turbines. TBC systems consist of a multilayer coating to prevent thermal degradation and oxidation.

The most efficient technique of deposition used for the ceramic layer is the electron beam physical vapor deposition (EB-PVD). It leads to a columnar microstructure with high thermal compliance. However, this structure induces a higher thermal conductivity for the ceramic layer than the typical homogeneous structure obtained by atmospheric plasma spraying (APS).

In this study, suspension plasma spraying (SPS) was used to demonstrate the ability to implement TBC with higher performances. Many studies showed the opportunity, by using SPS process, to produce TBC with a columnar structure and low thermal conductivity. This work details microstructures obtained by SPS. A focus is made on the growth of columnar structures. Thermal conductivity of SPS coatings is also presented.