How does plasma spray differ from EB-PVD in TBC application methods?

Core Differences Between Plasma Spray and EB-PVD

Plasma spray and electron beam physical vapor deposition (EB-PVD) are both proven methods for applying thermal barrier coatings (TBCs), but they deliver fundamentally distinct coating structures and performance levels. Plasma spraying is faster and more cost-efficient, while EB-PVD produces highly engineered, columnar coatings with superior strain tolerance for extreme conditions found in aerospace and aviation propulsion systems and high-efficiency power generation turbines.

Plasma Spray Application

Plasma spraying uses a high-energy plasma jet to melt ceramic powders and propel them onto the substrate. This creates a lamellar, slightly porous coating structure offering excellent insulation but limited elasticity. It is effective for components manufactured through superalloy equiaxed crystal casting where moderate thermal cycling is expected. However, because of its layered structure, plasma-sprayed coatings may develop microcracks and require reinforcement via post-treatment such as hot isostatic pressing (HIP).

EB-PVD Application

EB-PVD vaporizes ceramic materials under vacuum using an electron beam and condenses them onto the component surface, forming a columnar microstructure. This structure allows elastic deformation during rapid temperature changes, significantly improving crack resistance and spallation durability. EB-PVD is ideal for turbine blades and hot-section parts produced via single crystal casting and superalloy directional casting, where reliability and creep resistance are critical.

Although EB-PVD requires vacuum equipment and is more costly, it provides superior adhesion and strain tolerance for high-speed rotating components operating above 1100 °C.

Integration with Processes

Prior to coating, substrates are prepared using precision superalloy CNC machining and surface conditioning. After application, material testing and analysis verify coating density, adhesion strength, pore distribution, and thermal resistance before deployment.

Summary

Plasma spray is economical and suitable for moderate environments, whereas EB-PVD produces high-performance columnar coatings for components exposed to severe thermal gradients and mechanical stress.