1 research outputs found
Synergy between Galvanic Protection and Self-Healing Paints
Painting is a cost-effective technique
to delay the onset of corrosion
in metals. However, the protection is only temporary, as corrosion
begins once the coating becomes scratched. Thus, an increasingly common
practice is to add microencapsulated chemical agents to paint in order
to confer self-healing capabilities. The additive’s ability
to protect the exposed surface from corrosion depends upon (i) how
long the chemical agent takes to spread across the exposed metal;
(ii) how long the agent takes to form an effective barrier layer;
and (iii) what happens to the metal surface before the first two steps
are complete. To understand this process, we first synthesized 23
± 10 μm polyurea microcapsules filled with octadecyltrimethoxysilane
(OTS), a liquid self-healing agent, and added them to a primer rich
in zinc, a cathodic protection agent. In response to coating damage,
the microcapsules release OTS into the scratch and initiate the self-healing
process. By combining electrochemical impedance spectroscopy, chronoamperometry,
and linear polarization techniques, we monitored the progress of self-healing.
The results demonstrate how on-demand chemical passivation works synergistically
with the cathodic protection: zinc preserves the surface long enough
for self-healing by OTS to reach completion, and OTS prolongs the
lifetime of cathodic protection