A Laser Interferometric Study of Corrosion of Coated and Uncoated Metals. II— Corrosion of Armco Iron with a Porous Epoxy Primer

Abstract Bare and epoxy primer coated Armco iron was caused to corrode in a solution of Mohr's salt with citric acid or sodium citrate added. Citric acid caused enough bubble formation to reduce the usefulness of interferograms. Sodium citrate addition caused no bubbles and kept the iron from precipitating or coloring the solution noticeably. Results of the bare iron were as expected. Coated iron required only 2 to 3 times the bare electrode potential to cause the same corrosion current to flow. Iron was being removed and presumably sequestered in the coating. A prepared holiday in the coating was monitored interferometrically.