Surface morphology control of laser-textured aluminum alloy and coating adhesion enhancement mechanisms: modelling and experiments

To address interfacial delamination of spacecraft thermal control coatings, this study employs laser texturing to construct controllable surface microstructures on aluminum alloy substrates. Process parameters were optimized using Taguchi experimental design, and surface morphology evolution was analyzed through combined experiments and numerical simulations. Results show that single pulse energy is the dominant factor governing surface roughness and microstructural features. As laser energy increases, micro-pits deepen and splashing intensifies, while the substrate microstructure remains stable. Finite element simulations identify 0.80 mJ as the critical threshold at which the governing mechanism transitions from heat conduction to evaporation–recoil dominance. At 1.00 mJ, enhanced inertial flow further reshapes pit geometry, maximizing mechanical interlocking despite a slight reduction in surface polarity. Higher laser energy also drives the transformation of the surface oxide from a hydroxyl-rich porous layer to a denser alumina film, significantly improving surface hydrophilicity. Stress analysis of droplet spreading confirms that the textured morphology induces stress concentration and retention, indicating mechanical interlocking as the primary adhesion mechanism. The enhanced coating adhesion is attributed to the synergistic effects of mechanical anchoring, geometric interlocking, and laser-induced surface activation. This work clarifies the multiphysical mechanisms underlying laser-textured interfacial strengthening for reliable thermal control surface design.