Application of laser ablation in adhesive bonding of metallic materials: A review

Surface treatments have been widely applied to a variety of metallic materials in order to modify their physicochemical properties and to improve both strength and durability of adhesive-bonded joints. Among available surface treatment methods, laser ablation has the advantages of efficiency, environmental friendliness and easy industrialization. In this work, the principle of laser ablation and its effect on the physicochemical properties of metallic materials are reviewed. The mechanisms accounting for the improved bonding strength and corrosion resistance of the adhesive-bonded joints fabricated from laser-ablated metallic materials are reviewed and discussed. Bonding strength of laser-ablated adhesively bonded joints increases with the increase of roughness and wettability of the metallic adherend surface, and the surface roughness contributes to the improved joint strength only when the adhesive is capable to sufficiently wet the laser-ablated surface to form mechanical interlocking at the bonding interfaces. Although the laser-ablated surfaces are more active with lower polarization resistances and higher corrosion current, which suggests that the laser-ablated surfaces are more susceptible to corrosion, the increased roughness by laser ablation plays a crucial role in the improved corrosion resistance of laser-ablated adhesively bonded joints, as rough surfaces effectively retard the diffusion of corrosive solution.