Development of an Electrochemical Method for Field Testing of Protective Coatings
Abstract
Nine different coating systems on cold rolled steel have been tested by recording of EIS data during immersion in 0.5 N NaCl (open to air). One set of samples has been tested in the as received condition and after application of an artificial defect. Another set was tested after outdoor exposure for two years at Cape Canaveral, Florida. For this set the susceptibility to cathodic delamination was also evaluated. For the set which was tested in the as-received condition for one year, the sample with an all latex coating was eliminated from further testing since the coating was so porous that the impedance spectra resembled those usually found for bare steel. In long term testing, coating damage was observed only for the alkyd enamel, the alkyd enamel Si-alkyd and the zinc-rich primer epoxy polyamide polyurethane systems. For the set which was tested for 55 d after outdoor exposure significant coating damage could only be detected for the alkyd enamel si alkyd coating. The coating properties degraded faster than for the as received sample indicating that outdoor exposure had weakened the coating. In the cathodic delamination tests the largest damage occurred for the other alkyd based coatings.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 31, 1991
- Accession Number
- ADA245872
Entities
People
- Florian Mansfeld
Organizations
- University of Southern California