Synergistic effects of laser-induced dual-layer structure on CMAS corrosion performance of thermal barrier coatings

• Laser-induced dual-layer structure reduces CMAS-induced phase transformation by 57%. • Nanoparticle layer sacrificially reacts with CMAS to form protective c-ZrO 2 . • Dense underlayer with high cohesive energy blocks CMAS infiltration. • Molecular dynamics simulations reveal atomic-scale mechanisms of CMAS corrosion suppression. • Finite element method and molecular dynamics simulations uncover nanoparticle formation dynamics. Thermal barrier coatings are susceptible to corrosion by molten silicate deposits, commonly referred to as “CMAS” based on their primary constituents (CaO-MgO-Al 2 O 3 -SiO 2 ). This has become a growing concern in modern gas turbines. To address this issue, we fabricated a dual-layer surface structure on plasma-sprayed 8YSZ coatings in one step using a KrF excimer laser. This structure comprises a nanoparticle-deposited layer on top of a dense melted layer. The influence of laser glazing parameters on the thickness of in-situ formed dual layers was experimentally investigated, and the results obtained here validate those derived from the combined finite element method. The volume fraction of monoclinic zirconia phase induced by CMAS attack was reduced by 57.2% in the laser-glazed coatings after CMAS corrosion for 10 h. The mechanisms underlying the enhanced CMAS corrosion resistance were established via molecular dynamic simulations, revealing a synergistic effect: the nanostructured ceramic top layer with lower cohesive energy is inferred to act as a preferential reaction layer and the dense underlying layer suppresses the diffusion of CMAS into the interior of the coating. Furthermore, despite surface densification, laser glazing does not degrade the thermal insulation performance of the thermal barrier coatings.