Passivation of Steel with Aqueous Amine Solution.
DEPARTMENT OF THE NAVY WASHINGTON DC
Pagination or Media Count:
This is a method for passivating steel surfaces to prevent flash rusting by ensuring that the steel surface remains in an alkaline condition, following cleaning, until all water is evaporated. A 5 to 10 percent citric acid solution, for example, adjusted to a ph of about 3.5 using amonia or triethanolamine is used to clean and derust the steel surfaces down to bare metal and applied at approximately 160 F. The cleaned metal surfaces are washed down with a 3 percent triethanolamine solution to neutralize and wash out any remaining citric acid solution. A passivating aqueous solution of 1 percent triethanolamine is then applied to the metal surface and dried to leave the surface slightly alkaline. The surface is then ready to be preserved with epoxy or other coatings.
- Properties of Metals and Alloys