There is a continuing quest in the anticorrosion coating industry for a rapid test method that would enable early detection of coating failure and correlate well with field observations. While the Salt Spray Fog Test (ASTM B117) is a widely used technique to rate the efficacy of newly developed anticorrosive coatings, the test is qualitative, and the duration is relatively long. The test also fails to differentiate incremental improvements in corrosion resistance, which prevents obtaining directional information for guiding the development of new technologies. Coatings achieve anticorrosive performance through three primary mechanisms: 1) barrier protection, 2) sacrificial (galvanic) protection, and 3) inhibitive protection. In pigmented coating formulations, good barrier to water, oxygen, and ions is believed to be one of the critical parameters for corrosion performance. Herein, fundamental insights on the barrier properties of pigmented coating films were studied by Dynamic Vapor Sorption (DVS) and Electrochemical Impedance Spectroscopy (EIS). Water permeability parameter from DVS and ion permeability parameter from EIS were demonstrated to be good indicators of the corrosion performance in the salt fog test and were also correlated well with the state of pigment dispersion in the dry film. These rapid test methods can be used as first pass screens for new anticorrosive coating technologies.<br/>

Dynamic vapor sorption and electrochemical impedance spectroscopy as rapid screening tests for anti-corrosion coatings

254th National Meeting (2017)

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