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An evaluation of corrosion protection by two epoxy primers on 2219-t87 and 7075-t73 aluminum
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Mendrek, M. J. |
| Copyright Year | 1992 |
| Description | A comparison of the corrosion protection provided by two amine epoxy primers was made using salt fog, alternate immersion, and total immersion as exposure media. The study is the result of a request to use an unqualified low volatile organic carbon (VOC) primer (AKZO 463-6-78) in place of the current primer (AKZO 463-6-3) because environmental regulations have eliminated use of the current primer in many states. Primed, scribed samples of 2219-T87 and 7075-T73 aluminum were exposed to 5-percent NaCl salt fog and 3.5-percent NaCl alternate immersion for a period of 90 days. In addition, electrode samples immersed in 3.5-percent NaCl were tested using electrochemical impedance spectroscopy (EIS). The EG&G model 368 ac impedance measurement system was used to monitor changing properties of AKZO 463-6-78 and AKZO 463-6-3 primed 2219-T87 aluminum for a period of 30 days. The response of the corroding system of a frequency scan can be modeled in terms of an equivalent circuit consisting of resistors and capacitors in a specific arrangement. Each resistor/capacitor combination represents physical processes taking place within the electrolyte, at the electrolyte/primer surface, within the coating, and at the coating/substrate surface. Values for the resistors and capacitors are assigned following a nonlinear least squares fit of the data to the equivalent circuit. Changes in the values of equivalent circuit parameters during the 30-day exposure allow assessment of the time to and mechanism of coating breakdown. |
| File Size | 6488753 |
| Page Count | 42 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_19930004528 |
| Archival Resource Key | ark:/13960/t6m091h2j |
| Language | English |
| Publisher Date | 1992-10-01 |
| Access Restriction | Open |
| Subject Keyword | Nonmetallic Materials Spectroscopy Electrochemical Corrosion Aluminum Electrodes Corrosion Prevention Impedance Measurement Epoxy Resins Primers Coatings Corrosion Tests Electrolytes Protective Coatings Alternating Current Equivalent Circuits Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Technical Report |
