OXIDATION RESISTANT CATHODIC ARC PVD MCRALY COATINGS

MCrAlY coatings are widely used to protect turbine blades and vanes in aero engines and gas turbines from oxidation and hot corrosion. These coatings can serve as overlays or bond-coats for thermal barrier coatings (TBCs). Traditional MCrAlY coatings are typically applied through thermal spray (TS) methods or electroplating, however MCrAlY coatings produced by cathodic arc physical vapor deposition (PVD) offer several significant advantages. PVD MCrAlY coatings exhibit superior surface adhesion, high density, and exceptional uniformity on complex geometries such as airfoils. A PVD NiCoCrAlY coating provides the same oxidation resistance at 1000°C as a low-pressure plasma spray (LPPS) NiCrAlY coating by forming a dense alumina scale, despite being only 50-70 µm thick—about half the thickness of conventional TS MCrAlY coatings. Additionally, PVD NiCrAlY coatings show a significantly lower surface roughness (Ra = 3-4 µm), which can be further smoothed by post-treatment, benefiting the application of EB-PVD TBCs. The cathodic arc PVD process is highly reliable and reproducible, does not block cooling holes of airfoils (no masking required), and is cost-effective for serial production. Production coating machines, such as the INNOVENTA coater family, are available in various chamber sizes, allowing for large-scale, efficient batch loading and enabling industrialization. These systems are designed for high-throughput production while maintaining consistency and quality. The target alloy composition can be tailored, and the recycling of targets is being explored to enhance sustainability. Initial testing of PVD MCrAlY as bondcoats for TBCs shows promising results, indicating potential for high-performance coatings in aerospace applications.