Comparison of Electrochemical Impedance Spectroscopy (EIS) Results for Accelerated Exposures versus Outdoor Exposure
Abstract
Cold-rolled steel and aluminum 2024 T3 panels were coated with 4 combinations of the chemical agent-resistant coating system (CARC) and exposed to 4 accelerated environments and outdoor environments at Cape Canaveral. The accelerated exposures included ASTM B117, ASTM D5894, and ASTM D5894 modified with 1 week of ASTM B117 or SAE J2334 in lieu of 1 week of ASTM G85. Electrochemical Impedance Spectroscopy (EIS), color, and gloss measurements were taken initially and at regular intervals during exposure. It was found that failure of these coating systems due to creep from scribe occurred before significant degradation was noticed using EIS, in part due to poor signal-to-noise in the electrochemical measurement. For systems where this was the case, samples were recoated and subjected to the accelerated environment with EIS measurements taken at regular intervals within the exposure. It was found that certain combinations of approved primer/topcoat demonstrate consistently better corrosion performance than other approved combinations. The choice of topcoat appears to have a greater impact than the choice of primer. Further, this testing validated the pretreatment and coating approval procedures that require outdoor exposure. This report compares the results of the outdoor exposures and accelerated corrosion. Also, EIS measurements generated from a second set of laboratory-accelerated corrosion panels were compared to the EIS measurements from the original outdoor set.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 18, 2018
- Accession Number
- AD1060246
Entities
People
- Christopher J. Miller
Organizations
- United States Army Research Laboratory