Plasma spray-physical vapor deposition (PS-PVD) environmental barrier coatings (EBCs) of Yb2Si2O7 were deposited on SiC and exposed in a steam environment (90% H2O/O2) at 1426 °C to form a thermally grown oxide (TGO) layer between the substrate and EBC. In advanced ceramic material systems such as coated ceramic matrix composites (CMCs), the TGO layer is the weak interface and directly influences component lifetimes. The effects of surface roughness and TGO thickness on the adhesion strength were evaluated by mechanical testing of the coatings after exposure. Morphology and oxide layer thickness were analyzed with electron microscopy while the composition and crystal structure were tracked with X-ray diffraction. The strength of the system is evaluated with respect to oxidation rate to give a qualitative understanding of coating durability.

Ceramic matrix composites (CMCs) and environmental barrier coatings (EBCs) are key technologies that can enable improvements in the thermal and propulsive efficiency of gas turbine engines. However, CMCs and EBCs are susceptible to various life limiting damage modes associated with the engine operating environment such as oxidation, recession, thermomechanical stress/strain, corrosion, foreign object damage (FOD), and solid particle erosion (SPE). Despite its importance, there is a limited understanding of the SPE behavior of CMCs and EBCs in the literature. This paper reviews the status of SPE research for CMCs and EBCs and provides a perspective towards future research.

Solid particle erosion (SPE) is a common phenomenon observed in gas turbine engines. Particles entrained in the gas flow impact engine hardware, resulting in micro-scale damage that leads to deleterious effects such as material removal. For protective coatings, damage due to SPE is a key concern, since it can negatively affect the durability of the coating and subsequently the life of the underlying component. In this work, the high-temperature SPE behavior of two state-of-the-art environmental barrier coatings (EBCs) deposited via air plasma spray (APS) is investigated using alumina erodent to understand the effect of particle kinetic energy, impingement angle, and temperature. The SPE behavior of the EBCs is also compared to APS and electron beam–physical vapor deposition (EB-PVD) thermal barrier coatings (TBCs) to elucidate similarities and differences in the erosion response. The EBCs were more susceptible to SPE than the EB-PVD TBC but had greater SPE resistance compared to the APS TBC. Coating microstructure and porosity were shown to have a strong influence on the observed behavior.