Substitute conversion coatings on aluminum for waste minimization
- Sandia National Labs., Albuquerque, NM (United States)
- Virginia Univ., Charlottesville, VA (United States). Center for Electrochemical Sciences and Engineering
Chromate conversion coatings such as Parker Company`s Alodine coatings are widely used to increase the corrosion resistance of aluminum and aluminum alloys. The primary disadvantage of chromate-based processes is that they use and produce as waste hexavalent chromium (Cr{sup 6+}). We have discovered that the corrosion resistance of Al can be increased by forming an inorganic barrier coating using chemicals that pose a relatively small environmental hazard. These new coatings are formed using a process that is procedurally identical to the basic chromate conversion process. We have prepared new and conventional coatings on 1100 (99.0 Al minimum), 2024-T3 (Al-Cu-Mg) and 7075-T6 (Al-Zn-Mg) commercial sheet stock for accelerated electrochemical testing and coating conductivity testing. Results show that the new coatings offer increased corrosion resistance compared to uncoated Al, but do not yet match the performance of the chromate conversion coatings. The conductivity of these new films on 1100 Al is comparable to that of Alodine coatings; however, the new coatings are more resistive than Alodine coatings on 2024-T3 and 7075-T6.
- Research Organization:
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 721446
- Report Number(s):
- SAND-91-1808C; CONF-9110172-3; ON: TI91021395
- Resource Relation:
- Conference: 17. DOE compatibility and aging and service life conference,Golden, CO (United States),1-3 Oct 1991; Other Information: PBD: [1991]
- Country of Publication:
- United States
- Language:
- English
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