Study on the Laser Ablation Resistance and Damage Mechanism of ZrO2 Coatings Under High-Speed Airflow

To investigate the laser ablation resistance and damage mechanism of ZrO2 ceramic coatings under high-speed airflow, a ZrO2 coating was prepared on an aluminum alloy substrate via atmospheric plasma spraying. Laser ablation tests were conducted under different Mach number airflow conditions using a laser ablation test platform. The results show that the coating exhibits a high reflectivity of approximately 97%, and its laser energy coupling coefficient (3%) is about 79% lower than that of the substrate. In the absence of airflow, laser irradiation induces a phase transformation from tetragonal to cubic in the coating, while high-speed airflow suppresses this transformation through convective cooling. The extent of coating damage intensifies with higher laser power and smaller spot sizes. High-speed airflow primarily negatively impacts the ablation resistance by enhancing molten material migration, increasing the cooling rate, and strengthening aerodynamic shear effects. After ablation, the coating can be divided into unaffected, lightly affected, and highly affected zones. High-speed airflow inhibits the melting process, resulting in fewer cracks and a refined grain size due to rapid cooling. The ablation mechanism analysis reveals that irradiation forms a molten pool at the center, which expands and ejects material, creating an ablation crater. Thermal stress during cooling induces micro-cracks. The introduction of high-speed airflow effectively removes molten material, disperses the plasma plume, increases the ablation rate and crater depth, and causes asymmetric cooling that alters thermal stress distribution, leading to directional crack propagation. The study demonstrates that high-speed airflow transforms the laser ablation mechanism from a thermo-mechanical coupled process into a dynamic, multi-field coupled process involving thermal, mechanical, and aerodynamic interactions.