Surface Quality Impact of Replacing Vapor Degreasers with Aqueous ImmersionSystems

摘要

With effective vapor degreasing solvents environmentally suspect, other methodsof cleaning metal surfaces must be used. Aqueous immersion cleaning, currently the preferred method for intermediate, lighter duty cleaning, is a promising alternative for precleaning and degreasing. Alkaline cleaners are the principal aqueous cleaner group and represent the most workable, broad substitute for vapor degreasers. The efficiencies of aqueous immersion degreasing and vapor degreasing for removing contaminants from an aluminum surface are compared. Intentionally soiled, artificially weathered 7075 aluminum panels are degreased and then either anodized or chemically conversion coated. The quantity and composition of the contaminant is determined after the cleaning. The performance of the coating is then ascertained and correlated with the contaminant history. The degreasing system is shown to have no effect on the performance of anodized or chemically conversion coated aluminum surfaces. Performance is assessed in terms of resistance to both corrosion and abrasion and on the integrity of the oxide coating. The subsequent light duty immersion cleaning and pickling removes any soil that survives the degreasing. Very little contamination survives the light duty cleaning.