Self-repairing coating for corrosion protection of aluminum alloys

The development of effective anticorrosion pre-treatments for metallic substrates is an issue of great importance for durability of metal structures and components. In this work, we proposed and demonstrated the concept of self-repairing coating for corrosion protection of aluminum alloys, using cagelike oil core/silica gel shell particles. These micron-scale, cagelike smart microspheres with opened and closed pores were successfully fabricated, and at the same time encapsulated repairing agent (methyl methacrylate) and catalysts (potassium persulfate and sodium thiosulfate) into the microspheres, respectively. Such smart particle composites (SPCs) were prepared based on an interfacial self-assembly process and sol-gel reaction. They were then self-assembled on the AA2024 aluminum alloy surface, followed by the application of a sol-gel film. The hybrid film worked as a primer coating featuring the self-repairing property. Both the EIS and SEM/EDS data demonstrated that the encapsulated repairing agent was released as a response to external stimulus (scratches) and polymerized to repair the coating defects. By comparing the corrosion rate of AA2024 in three coating systems, the self-repairing effect is quantified to be 22% after 2 h immersion in deoxidized 3% NaCl solution. (C) 2008 Elsevier B.V. All rights reserved.