Degradation of Powder Epoxy Coated Panels Immersed in a Saturated CalciumHydroxide Solution Containing Sodium Chloride

摘要

Blasted-steel panels were coated with two commercial powder epoxy coatings.Approximately half (80) of the coated panels were scribed; while the other half remained defect-free. All of the panels were immersed in a saturated calcium hydroxide solution containing 3.5 percent sodium chloride maintained at either 35 or 50 deg. C. None of the unscribed panels degraded after 3074 h of immersion at 35 deg C; whereas, all of the scribed panels degraded within 24 h after immersion, regardless of the immersion solution temperature. Scribed panels degraded in three ways: (1) anodic corrosion, (2) Cathodic disbondment, and (3) wet-adhesion loss.