Corrosion and wear resistant yttria-stabilised zirconia (YSZ) coatings on stainless-steel via laser deposition

Yttria-stabilized zirconia (YSZ) is a promising protective coating for stainless-steel, but its direct deposition has achieved limited success due to difficulties in forming dense coatings with strong interfacial bonding. In this study, laser deposition (LD) is applied to directly deposit YSZ on stainless-steel to address this challenge. A systematic optimisation of LD parameters is first conducted using surface inspection to identify defects, complemented by a data-driven segmentation approach to quantitatively characterise protrusions and depressions, and their spatial distribution. A parameter set (250 W, 900 mm/min) was identified to achieve defect-minimised surface quality. Microstructural characterisation revealed an interface with pronounced metallurgical bonding and substantial interfacial diffusion is achieved. The YSZ coating exhibits a hardness of 15.7 ± 0.5 GPa, approximately six-times that of stainless-steel, and a 4.7-fold improvement in wear resistance, attributing to the intrinsic hardness of YSZ and the strong interfacial bonding. Electrochemical analysis in 3.5 wt% NaCl reveals a ten-fold reduction in corrosion rate, with the corrosion current density decreasing from 0.41 ± 0.15 to 0.036 ± 0.009 µA cm −2 , indicating that the coating acts as an effective physical barrier. The findings confirm the feasibility of direct LD for producing dense, well-adhered YSZ coatings with reliable protective performance against wear and corrosion.