UMR Researchers Work To Remove Toxic Components From Aluminum Coatings

The funding is for a joint research project between UMR and Boeing Co. todevelop more environmentally acceptable corrosion protection for metallicparts of aircraft. This research should also be applicable to otheraluminum products.

"We have proven in our laboratories at UMR that our research efforts toremove toxic materials from aluminum components work," says Dr. James O.Stoffer, director of the Graduate Center for Materials Research at UMR andproject director.

Aluminum used in the construction of aircraft and cars is treated bydipping the metal in chromic acid, one of the most toxic materials knownand one that is targeted for elimination from the workplace by the U.S.Environmental Protection Agency. The chromic acid coats the aluminum with athin layer of chromate material, making it resistant to corrosion.

"The aluminum is then painted with an epoxy paint that has strontiumchromate components in the paint," says Stoffer, who also is a professor ofchemistry at UMR. "The strontium chromate is also toxic."

The interdisciplinary research effort at UMR is helping the U.S. Air Forceuse an alternative to chromate in its aircraft aluminum. "Our research teamhas developed a system to replace chromate conversion coatings by using athin layer, known as a cerium conversion coating, to be used as a firstcoating on the aluminum," Stoffer says. This process also includes painting a non-toxic material known asE-coat on top of the aluminum, providing added protection. "This processreplaces all the toxic materials used on the aluminum," Stoffer says.

The crucial test for the new process system is that the conversion coatingshave to survive 336 hours in a salt fog chamber with no signs of corrosion.And a painted aluminum surface with an X scribe down to base metal, mustsurvive 2,000 hours, Stoffer says. "Our system does both," he adds.

"But a lot still has to be done related to optimization, scale up andimplementation of the technology within Boeing," Stoffer says. Thisincludes part development and sizing and fitting the parts.

The tests, which have been conducted at UMR and at Boeing, will continueuntil the completion of military specifications, Stoffer says.

The research project began in 1994 as part of a grant to UMR fromMcDonnell Douglas (which Boeing later purchased), Monsanto and the MissouriResearch Training Center at UMR. "The initial grant was for $150,000, butwe have received continuous funding for this project since then," Stoffersays. "The Air Force and Boeing also funded this project with a $459,000grant to UMR in 1996.

"In addition," Stoffer says, "the Office of Naval Research, with additionalfunding from TDA Research Inc. of Denver, Colo., presented UMR with a$300,000 grant for three years in 1996."

The research team from UMR is being led by Stoffer, Dr. Thomas J. O'Keefe,Curators' Professor of metallurgical engineering, and Dr. Harlan U.Anderson, Curators' Professor of ceramic engineering. "We have also had anumber of graduate students working with us as a team on this researchproject for the last five years, and efforts to increase the number ofgraduate students are now in process," Stoffer sa