Alkyd coated laser induced graphene patches for corrosion resistance of metal substrates

Corrosion can severely degrade surfaces and materials, impacting both functionality and safety. Laser-induced graphene (LIG) offers substantial corrosion resistance, making it an ideal material for protecting metals, such as carbon steel. This study developed adhesive, corrosion-resistant LIG patches on polyimide (PI) layers, enhanced with an alkyd resin coating, and applied to pretreated aluminum surfaces. LIG was synthesized using laser powers of 6, 8, 10, and 12 W, followed by alkyd coating for improved performance. Results of EDS, SEM, TGA, XRD, Raman spectroscopy, and surface-wetting properties are studied. SEM and XRD analyses revealed that a lower laser power (6 W) produced uniform, crystalline LIG, whereas a higher power (12 W) caused defects and porosity. Corrosion tests in an alkaline environment showed that the A-LIG6@PI patch had the best structural integrity, with minimal pitting after 96 h, outperforming other samples. The electrochemical analysis demonstrated a corrosion inhibition efficiency of 98.36% for A-LIG6@PI, with a corrosion current density of 0.11 µA/cm² and polarization resistance (Rp) of 8.51 × 10⁶ Ω·cm². Contact angle measurements confirmed enhanced hydrophobicity, with A-LIG6@PI showing an 88° angle compared to 58° for bare LIG. The electrochemical analysis demonstrated a corrosion inhibition efficiency of 98.36% for A-LIG6@PI in 3.5 wt% NaCl solution, outperforming higher-power LIG samples (e.g., 66.81% for uncoated LIG12@PI), while maintaining structural integrity on aluminum substrates after 96 h. These results highlight the potential of using lower laser power to create durable, corrosion-resistant graphene-based coatings suitable for flexible electronics, automotive components, marine structures, oil and gas pipelines, and protective applications.