Investigation of underfilm corrosion using pH sensitive microcapsules

摘要

The corrosion protection ability of pH sensitive microcapsule (pH-MC) containingrncorrosion inhibitors was evaluated by salt spray test (SST), potentiodynamicrnpolarizations scans (PDS) and open circuit potential (OCP). Cerium nitrate wasrnencapsulated in pH-MC by water-in-oil emulsion polymerization. Particle size ofrncerium nitrate encapsulated pH-MC (Ce-MC) was controlled in the range of 7 μm torn18 μm by adjusting the agitating speed of emulsion. Underfilm corrosion on steelrnsubstrate was improved by adding Ce-MC into the coating matrix, particularly smallerrnparticle size displayed better corrosion inhibition proerties. PDS indicated that thernsuppression of anodic reaction may be the reason for underfilm corrosion protection.rnThe corrosion potential of the coatings containg Ce-MC increased with immersionrntime indicating a possible self healing protection mechanism.