Gradient‐Multiscale Synergistic Surface Treatment for CARALL

ABSTRACT To address the challenge of efficiently and economically enhancing the interfacial strength of large irregular‐shaped components, this study proposes a gradient multiscale synergistic combined surface treatment method. The mechanism of this method and its interfacial enhancement effects are systematically investigated through scanning electron microscopy (SEM), energy dispersive spectroscopy, X‐ray photoelectron spectroscopy (XPS), and single‐lap shear tests. Results indicate that carbon fiber reinforced aluminum laminate (CARALL) treated with this method develops a gradient interfacial microstructure and generates abundant reactive functional groups capable of chemically reacting with epoxy resin. These structural and chemical modifications lead to a 74% increase in interfacial strength, reaching 18.4 MPa, compared to untreated specimens. Notably, the entire treatment process requires only 49 min. To validate engineering applicability, the proposed surface treatment is implemented on an 18‐m box‐type emergency bridge. Through experiments and numerical simulations, it is confirmed that the structure's maximum interfacial shear stress (15 MPa) remains safely below the enhanced interfacial strength (18.4 MPa), demonstrating the method's effectiveness for load‐bearing applications.