Corrosion Behavior of Primid Solidified Polyester Powder Coating in Marine Environment

The corrosion behavior of primid-curing solidified polyester powder coating defects in marine environment was investigated by CASS test, immersion test, electrochemical impedance spectroscopy (EIS) and scanning Kelvin probe (SKP). The results show that the primid-curing polyester powder coating has a small amount of blisters along the scratch edge, the maximu single side corrosion width is less than 0.5mm, and the surface adhesion is 0 after 240 hours' CASS test. The EIS map in 0.6mol/L NaCl solution exhibits that the corrosion rate of aluminu alloy is decreased with increasing immersion time and gradually stable. The scanning Kelvin spectrum reveals that the corrosion of the metal under the coating of the polyester powder is extended from scratch to the coating, the anode and the cathode are alternately changed, which leads to the expansion of the corrosion area.