NDLI: Thin-film sulfuric acid anodizing as a replacement for chromic acid anodizing

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Thin-film sulfuric acid anodizing as a replacement for chromic acid anodizing

Content Provider	NASA Technical Reports Server (NTRS)
Author	Kallenborn, K. J. Emmons, J. R.
Copyright Year	1995
Description	Chromic acid has long been used to produce a thin, corrosion resistant (Type I) coating on aluminum. Following anodizing, the hardware was sealed using a sodium dichromate solution. Sealing closes up pores inherent in the anodized coating, thus improving corrosion resistance. The thinness of the brittle coating is desirable from a fatigue standpoint, and chromium was absorbed by the coating during the sealing process, further improving corrosion resistance. Unfortunately, both chromic acid and sodium dichromate contain carcinogenic hexavalent chromium. Sulfuric acid is being considered as a replacement for chromic acid. Sulfuric acid of 10-20 percent concentration has traditionally been used to produce relatively thick (Types II and III) or abrasion resistant (Type III) coatings. A more dilute, that is five weight percent, sulfuric acid anodizing process, which produces a thinner coating than Type II or III, with nickel acetate as the sealant has been developed. The process was evaluated in regard to corrosion resistance, throwing power, fatigue life, and processing variable sensitivity, and shows promise as a replacement for the chromic acid process.
File Size	387102
Page Count	10
File Format	PDF
Alternate Webpage(s)	http://archive.org/details/NASA_NTRS_Archive_19950025351
Archival Resource Key	ark:/13960/t6838qx6p
Language	English
Publisher Date	1995-03-01
Access Restriction	Open
Subject Keyword	Nonmetallic Materials Thin Films Corrosion Resistance Fatigue Life Aluminum Anodizing Porosity Replacing Brittleness Protective Coatings Sealing Chromic Acid Sulfuric Acid Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science
Content Type	Text
Resource Type	Article

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