Localised electrochemical characterisation of dual silane functionalised graphene oxide/silane coatings on magnesium alloy by SECM

This study presents a localised electrochemical investigation of dual-silane functionalised graphene oxide (GO)/silane hybrid coatings developed on AZ31 magnesium alloy using Scanning Electrochemical Microscopy (SECM). The hybrid coatings were synthesised using 3-glycidoxypropyl trimethoxysilane (GPTMS), tetraethyl orthosilicate (TEOS) and γ-aminopropyl trimethoxysilane (APS), while GO was modified through a dual-silane functionalisation approach to improve dispersion, interfacial compatibility and coating barrier performance. The localised corrosion behaviour of coated and uncoated AZ31 alloy was evaluated in phosphate-buffered saline (PBS) solution under simulated physiological conditions. SECM current mapping demonstrated a substantial decrease in localised electrochemical activity for the hybrid coated alloy compared with bare magnesium alloy, confirming the formation of a more uniform and defect-resistant protective layer. The dual-silane modified GO effectively enhanced coating integrity and corrosion resistance by limiting electrolyte penetration and localised anodic activity. The developed hybrid coating system shows strong potential for corrosion protection of magnesium alloys in physiological environments.