Chromate-free corrosion resistant conversion coatings for aluminum alloys

Technical Report · Wed Mar 01 04:00:00 EST 1995

DOI:https://doi.org/10.2172/28379· OSTI ID:28379

Buchheit, R G; Drewien, C A; Martinez, M A ^[1]; Stoner, G E ^[2]

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1. Sandia National Labs., Albuquerque, NM (United States)
2. Univ. of Virginia, Charlottesville, VA (United States). Dept. of Materials Science

Inorganic polycrystalline hydrotalcite, Li{sub 2}[Al{sub 2}(OH){sub 6}]{sub 2}{center_dot}CO{sub 3}{center_dot}3H{sub 2}O, coatings can be formed on aluminum and aluminum alloys by exposure to alkaline lithium carbonate solutions. This process is conducted using methods similar to traditional chromate conversion coating procedures, but does not use or produce toxic chemicals. The coating provides anodic protection and delays the onset of pitting during anodic polarization. Cathodic reactions are also inhibited which may also contribute to corrosion protection. Recent studies have shown that corrosion resistance can be increased by sealing hydrotalcite coated surfaces to transition metal salt solutions including Ce(NO{sub 3}){sub 3}, KMnO{sub 4} and Na{sub 2}MoO{sub 4}. Results from these studies are also reported.

• Research Organization: Sandia National Labs., Albuquerque, NM (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC04-94AL85000
• OSTI ID: 28379
• Report Number(s): SAND--95-0280C; CONF-950201--2; ON: DE95007742
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM
ALUMINIUM ALLOYS
ALUMINIUM HYDROXIDES
CERIUM NITRATES
CHEMICAL COATING
CORROSION PROTECTION
CORROSION RESISTANCE
EXPERIMENTAL DATA
HYDRATES
LITHIUM CARBONATES
MANGANATES
MOLYBDATES
PITTING CORROSION
POTASSIUM COMPOUNDS
PROTECTIVE COATINGS
SODIUM COMPOUNDS