THE DEVELOPMENT OF A TWO-COMPONENT, MAGNESIUM-RICH PRIMER FOR CONTROLLING CORROSION OF ALUMINUM ALLOYS

摘要

It has recently been shown that commercially-available magnesium particles can be used to produce primers that provide corrosion protection to aluminum alloys by serving as a sacrificial metal. A polymer binder system that has enabled exceptionally good performance with magnesium particles was based on a three-component binder system comprised of an epoxy resin, di-isocyanate, and aminofunctional silane. Due to the complexity of the three-component system and variability in pot-life, a simpler one-or two-component binder system was desired that could provide equivalent or better performance than the three-component system. As a result, research was conducted to develop a two-component Mg-rich primer that provides excellent corrosion protection to aluminum alloys. As part of the investigation, several variables associated with the coating formulation were examined using open circuit potential measurements, electrochemical impedance spectroscopy, salt spray exposure testing, and scanning electron microscopy in conjunction with the energy dispersive X-ray technique. The results showed that all of the variables investigated which included epoxy resin molecular weight, curing agent functionality, epoxy/NH ratio, and Mg content significantly affected coating performance. An optimized formulation for the two-component primer was identified, which showed very similar corrosion protection performance to the extensively studied three-component, hybrid binder system for Mg-rich primers.