Session Details

Session 12: Advances in Surface Finishing

Abstract Number:

96

This talk summarizes novel completely non-chromate organic ‎coatings development for use on ‎plated steels. The organic coating ‎chemistry and formulation using polymeric Schiff base inhibitors ‎‎will be discussed.‎

Topics:

Advances in Research

Hexavalent chromium (Cr6+) containing sealers are primarily used to ‎enhance corrosion protection of ‎metal plating, Al anodizing and ‎other sacrificial layers when exposed to corrosive atmospheric ‎‎environments. The need to reduce or eliminate the use of Cr6+ ‎containing anodizing and passivating ‎sealing solutions remains a top ‎priority for the DoD to reduce risks associated with environmental, ‎‎human health, and compliance issues. Many Cr6+ free corrosion ‎inhibitors and coating systems have ‎been researched and ‎implemented to various extents over the last several decades. Most ‎corrosion ‎inhibitors can be classified as inorganic or organic based on ‎their molecular formula. The focus of this ‎study is organic inhibitors, ‎specifically those containing a Schiff base (SB) or an azomethine ‎‎functional group (--RC=N--). Boeing Research and Technology (BR&T) ‎has discovered a unique ‎functionality of these SB inhibitors that ‎enables high polarization resistance of Al when exposed to ‎chloride-‎containing corrosive media. Twenty- three different corrosion ‎inhibitors with the Schiff base ‎functionality were synthesized and ‎characterized using fourier-transform infrared spectroscopy ‎‎(FTIR) ‎and nuclear magnetic resonance spectroscopy (NMR). Corrosion ‎inhibition of the organic ‎inhibitors were evaluated using polarization ‎resistance and potentiodynamic scans of the metal ‎surface. ‎Electrochemical corrosion resistance performance of the inhibitors ‎were ranked using ‎inhibitor efficiency and the corrosion rate of the ‎metal was calculated using Faraday’s law and the ‎corrosion current ‎from potentiodynamic scans. BR&T is partnering with the Missouri ‎University of ‎Science and Technology (Missouri S&T) and the Naval ‎Air Systems Command (NAVAIR) to develop ‎and mature organic ‎Schiff base (SB) containing passivating solutions for zinc (Zn), zinc-‎nickel (ZnNi), ‎cadmium (Cd) plating.‎

APPLICATION OF SCHIFF BASE CHEMISTRY TO SURFACE ‎PASSIVATION OF PLATED STEELS

Waynie Schuette

Engineer

Boeing