Storage and Release of Corrosion Inhibitors from Commercial Primers

Commercial primers are applied on aluminum alloys that are used in aerospace applications to prevent corrosion attack from aggressive environment.  These primers contain some effective inhibitors that help combat against corrosion. During field operations, these primers store and release inhibitors to protect the substrate materials. The goal of this study is to characterize storing and releasing behaviors of these commercial primers to better understand rate and mechanism at which inhibitors are released. Three commercial primers are being investigated in this study; 1) Akzo Nobel 10P20-13 High Solid Primer that contains strontium chromate (SrCrO₄), 2) Deft 02GN087 (non-chromate), and 3) Hentzen 16708TEP (non-chromate). The primers were coated on a Teflon tape, then stripped off and broken to small pieces. Pieces of primers were exposed to different environments with varied Cl^- concentration, temperature, time, and pH.  Inductively Coupled Plasmas Mass Spectroscopy (ICP-MS) was used to analyze elements from the solution. Results have shown that SrCrO₄ primer release behavior follows power law kinetic. The effect of temperature changes the releasing mechanism of AkzoNobel primer. Chloride seems to promote release rate, and the effect of pH is still under investigation. Deft primer releases a large amount of Ca, but does not seem to be time dependent. Hentzen does not seem to release any soluble constituent to any extent.