Gradient-structured abradable coatings with particle-assisted intercolumnar fracture via plasma spray-physical vapor deposition

Achieving high abradability in ceramic seal coatings while retaining mechanical and thermal stability is a key challenge for advanced turbine engines. This work introduces a nanoparticle-assisted fracture pathway in yttria-stabilized zirconia (YSZ) coatings produced by PS-PVD. Optimizing the spray distance to 1400 mm yields a self-assembled gradient structure with a dense base layer for integrity and a porous top layer with enlarged intercolumnar spacing (∼14 μm) containing embedded nanoparticles. The optimized coating shows a 50% increase in material removal rate and a 12% reduction in surface hardness (69 HR15Y) compared with conventional YSZ, confirming enhanced abradability. Microstructural analysis indicates that nanoparticles serve as stress concentrators, promoting controlled intercolumnar fracture under shear and enabling localized energy dissipation without catastrophic spallation. This mechanism decouples abradability from overall porosity, providing new insight into microstructure–tribological interactions and offering a practical strategy for developing wear-tolerant, highly abradable coatings for next-generation aero-engine seals.