April 17, 2000

esearchers in the School of Engineering and at Inframat Corp. have developed a revolutionary new coating for use by the Navy on ships and submarines, that is much more durable than the coatings used today.

This nanostructured alumina-titania coating has structural features, such as crystal size, that are 100 to 1000 times smaller than those found in conventional coatings. These tiny structural features, which can only be seen with modern electron microscopes at magnifications greater than 50,000 times, give nanostructured coatings extraordinary wear, impact, toughness, and adhesive properties.

The nanostructured alumina-titania coating will be used by the Navy to coat shaft, pumps and other moving parts.

"There is a continual need for coatings with improved durability," says Maurice Gell, professor-in-residence of metallurgy and materials engineering and program manager. "And there is an agency-wide effort in the Navy to develop technologies that will allow ships to stay at sea for longer periods of time without having to come in for repair.

"We've developed the first of a revolutionary new class of materials in which the scale of the microstructure is finer than anything in existence today," Gell says. These finer features will give nanostructured materials, like metals and ceramics, superior engineering properties - hardness, strength, toughness, ductility, and wear resistance.

These coatings are applied using nanostructured powder and commercial plasma spray processes. One of the difficult tasks in the program was learning how to inject nanostructured powder in a plasma spray flame operating at temperatures greater than 15,000 degrees Kelvin, more than three times the temperature of the surface of the sun, and preventing the powder from melting and destroying the nanostructure.

The research has been conducted under a 4 1/2 year, $4 million contract with the Office of Naval Research. The interdisciplinary project is now in its third year. The remaining time will be used to develop and implement additional nanostructured coatings. "In the remaining part of the program, it will be exciting to see how much additional potential there is in this new class of coating materials," says Eric Jordan, professor of mechanical engineering.

The area of nanostructured materials and devices has recently become a national initiative. President Clinton announced a commitment of $500 million to their development over a three-year period.

It is highly unusual for a university to conduct a program that involves research, development and technology implementation, Gell says.

The project was conducted with a multidisciplinary team led by Gell, and included faculty members Leon Shaw and Nitin Padture, of the Department of Metallurgy and Materials Engineering; and Jordan, Baki Cetegen and Ted Bergman, from the Department of Mechanical Engineering.

"This project is possible because of the availability of a sufficiently large group of quality faculty and the availability of modern facilities at the Institute of Materials Science and the Advanced Technology Institute," says Jordan. "Projects like this are one type of return on the investments made by the state in UConn, and future projects will depend on continued investment."

The nanostructured powder processing procedures were originally developed and patented by UConn, and an exclusive license was purchased by Inframat Corp., a small Connecticut company headquartered in North Haven. Inframat performed the critical processing of nanostructured powder and the plasma spray of nanostructured coatings, often working side by side with UConn personnel.

The coating has been qualified by the U.S. Navy, based on plasma spray trials of nanostructured coatings conducted at a Navy-approved supplier. The mechanical and environmental properties obtained in these Navy qualification trials duplicated the outstanding results obtained at UConn, Gell says. The Navy is now plasma spraying these coatings on a number of components for shipboard and submarine application.

Sherry Fisher