INFLUENCE OF NANOSTRUCTURED CLADDING OF Al₂O₃ AND ZrO₂ POWDERS WITH TITANIUM AND ALUMINUM ON THE CORROSION AND WEAR RESISTANCE OF PLASMA SPRAY COATINGS

Abstract

The paper investigates the relevant issue of improving the operational reliability of plasma-sprayed ceramic coatings widely used to protect machine parts and mechanical components from severe wear and corrosion degradation. Special emphasis is placed on a promising approach involving nanomodification of feedstock powders by forming thin nanostructured metallic shells on the surface of powder particles. This technique makes it possible to control the coating structure formation, enhance cohesive strength, and improve the overall set of physical and mechanical properties.

The study focused on oxide ceramic powders Al₂O₃ and ZrO₂ with a particle size range of 10–63 μm. Metallic shells were deposited using by arc vacuum method. The clad layer exhibited a bilayer structure consisting of an adhesive titanium sublayer and an outer aluminum layer. Coatings were deposited by plasma spraying under a laminar plasma jet regime, which ensured process stability and reduced particle oxidation during flight.

The morphology of the powders and the deposited coatings was examined by scanning electron microscopy combined with energy-dispersive X-ray analysis. It was established that the clad particles were characterized by a uniform distribution of the metallic shell and contributed to the formation of coatings with increased density. The thickness of the nanostructured layers ranged from 41 to 633 nm depending on the deposition conditions.

Corrosion resistance was evaluated using the polarization resistance method in a 10% H₂SO₄ solution. The results confirmed a significant improvement in the corrosion resistance of coatings produced from clad powders compared to coatings deposited from unmodified Al₂O₃ and ZrO₂ powders. Wear performance was assessed using a pin-on-disk test configuration. The coatings based on clad powders demonstrated consistently low wear after the running-in stage, whereas coatings produced from non-metallized powders showed catastrophic spalling and a wear rate 4–6 times higher. Thus, ion-plasma cladding of ceramic powders is an effective method for improving the durability of plasma-sprayed ceramic coatings under mechanical friction and aggressive environmental conditions.