Harnessing 3D Porous Cobalt Oxide Nanoflakes Grown on Metal for Exceptional Adhesion between Aluminum Surfaces and the Epoxy Matrix

The developments in the automotive and aerospace sectors require alternative structures to metals for diverse applications; therefore, lightweight polymer–metal hybrid composites with outstanding mechanical characteristics are synthesized. Herein, the modern nanoperfusion technology, which involves the in situ growth of 3D porous cobalt oxide nanoflakes (Co₃O₄ NFs) on the porous aluminum surface, is used. A rough surface with corresponding surface porosities of 21, 48.1, and 49.8% can be produced by anodization of aluminum at 8, 10, and 12 V, respectively. The samples anodized at 10 V are selected as a structure for the growth of 3D Co₃O₄ NFs at different hydrothermal temperatures (90, 120, and 160 °C). The bond strength and modulus of the toughness of the sample combining aluminum and 3D Co₃O₄ NF growth at 120 °C exhibit a substantial bonding strength, reaching a value of 14.27 MPa and 3.56 kJ m⁻³, respectively. The porous nature of the manufactured cobalt oxide nanoflakes allows the epoxy to penetrate, which enhances the bonding strength and thus improves the mechanical properties of the manufactured joints.