Accession Number:

ADA458368

Title:

A Comparison of Bulk Precipitated Cerium Oxide Powders and Cerium Conversion Coatings and the Influence of Hydrogen Peroxide on Their Formation (Preprint)

Descriptive Note:

Journal article preprint

Corporate Author:

MISSOURI UNIV-ROLLA

Report Date:

2006-03-01

Pagination or Media Count:

23.0

Abstract:

To better understand the role of hydrogen peroxide in the formation of cerium conversion coatings and precipitates, hydrated cerium oxidehydroxide materials obtained from aqueous solutions have been characterized by thermogravimetic methods, X-ray diffraction, and scanning electron microscopy. Powders were prepared by precipitation with sodium hydroxide from cerium III chloride solutions using either hydrogen peroxide or oxygen sparging to oxidize CeIII species to CeIV species. Cerium conversion coatings were deposited on Al 7075-T6 substrates using a spontaneous immersion process in a water-based solution containing CeCl3 and hydrogen peroxide. The results suggest that the cerium powders produced in the presence of hydrogen peroxide bear the most resemblance to the cerium conversion coatings, and that simulating the cerium conversion coating process through bulk precipitation tests is reasonable. Other significant observations were also made. One was that hydrogen peroxide lowers the pH required to precipitate cerium. Another was that a significant amount of oxygen was evolved upon heating both the cerium conversion coating and the cerium precipitates formed by using hydrogen peroxide as an oxidant. Lastly, the effect of hydrogen peroxide in the cerium conversion coating process is considered from the standpoint of corrosive attack on the aluminum substrates.

Subject Categories:

  • Physical Chemistry
  • Coatings, Colorants and Finishes
  • Properties of Metals and Alloys

Distribution Statement:

APPROVED FOR PUBLIC RELEASE