Nov. 16, 1998 ROLLA, Mo. -- Researchers at the University of Missouri-Rolla, working to remove toxic materials from aluminum components used in the aerospace industry, got a boost recently through $1.5 million in federal funding from the 1999 Defense Appropriations Bill.
The funding is for a joint research project between UMR and Boeing Co. to develop more environmentally acceptable corrosion protection for metallic parts of aircraft. This research should also be applicable to other aluminum products.
"We have proven in our laboratories at UMR that our research efforts to remove toxic materials from aluminum components work," says Dr. James O. Stoffer, director of the Graduate Center for Materials Research at UMR and project director.
Aluminum used in the construction of aircraft and cars is treated by dipping the metal in chromic acid, one of the most toxic materials known and one that is targeted for elimination from the workplace by the U.S. Environmental Protection Agency. The chromic acid coats the aluminum with a thin layer of chromate material, making it resistant to corrosion.
"The aluminum is then painted with an epoxy paint that has strontium chromate components in the paint," says Stoffer, who also is a professor of chemistry at UMR. "The strontium chromate is also toxic."
The interdisciplinary research effort at UMR is helping the U.S. Air Force use an alternative to chromate in its aircraft aluminum. "Our research team has developed a system to replace chromate conversion coatings by using a thin layer, known as a cerium conversion coating, to be used as a first coating on the aluminum," Stoffer says. This process also includes painting a non-toxic material known as E-coat on top of the aluminum, providing added protection. "This process replaces all the toxic materials used on the aluminum," Stoffer says.
The crucial test for the new process system is that the conversion coatings have 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, must survive 2,000 hours, Stoffer says. "Our system does both," he adds.
"But a lot still has to be done related to optimization, scale up and implementation of the technology within Boeing," Stoffer says. This includes part development and sizing and fitting the parts.
The tests, which have been conducted at UMR and at Boeing, will continue until the completion of military specifications, Stoffer says.
The research project began in 1994 as part of a grant to UMR from McDonnell Douglas (which Boeing later purchased), Monsanto and the Missouri Research Training Center at UMR. "The initial grant was for $150,000, but we have received continuous funding for this project since then," Stoffer says. "The Air Force and Boeing also funded this project with a $459,000 grant to UMR in 1996.
"In addition," Stoffer says, "the Office of Naval Research, with additional funding 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 a number of graduate students working with us as a team on this research project for the last five years, and efforts to increase the number of graduate students are now in process," Stoffer says.
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