Scalable Manufactured ZrO2-Al2O3 Heterostructured Coating with High Reflectivity and Enhanced Toughness for Space Laser Protection.

Developing ceramic coatings with high reflectivity, emissivity, and mechanical robustness is critical for enhancing laser protection and thermal management in various optical precision instruments and engineering equipment. However, insufficient optical and mechanical performance causes heat accumulation and fracture under thermomechanical stress that can lead to catastrophic failure. Herein, a scalable ZrO2-Al2O3 heterostructured coating featuring anti-laser ablation, thermal management, and toughness is fabricated via a facile yet effective strategy. The multiple scattering of the micro-convex structure on the coating surface and the refractive index mismatching at the heterogeneous interface enhance its reflectivity to 92% (780-2500 nm), while the enlarged effective radiation area improves its emissivity to 0.93 (8-25 µm). The combination of high reflectivity and low thermal conductivity of 0.6 W/(m K) enables the coating to achieve a laser damage threshold of 637 W cm-2 for 35 s, reducing the damage depth by 35.46% compared to a single Al2O3 coating. Notably, the fracture toughness of the coating reaches 6.77 MPa m1/2 due to the synergistic effects of zirconia phase transformation toughening and heterogeneous interface energy absorption. These characteristics make the ZrO2-Al2O3 heterostructured coating potential protective materials for various laser protection and thermal management applications.