Gun barrels coated with environmentally friendly tantalum-tungsten last three times as long as barrels coated with hazardous hexavalent chromium. 

 Medium caliber gun barrels, such as those mounted on trucks and helicopters, are made using chromium as a coating on the interior bore surfaces. This hard surface protects against propellant gases and wear and tear from projectiles when the gun is fired. Although the coating provides the desired properties, the hexavalent chromium used in the plating process is a known carcinogen, requiring time-consuming and expensive precautions that protect workers, as well as incurring substantial disposal costs.

Mr. Mark Miller and his colleagues developed a method for applying an environmentally benign tantalum-tungsten coating onto the interior surfaces of the gun barrels using an innovative explosive bonding process. Their work combined fundamental engineering, high-end computational modeling, and experimental research.

In addition to eliminating hazardous workplace exposure to hexavalent chromium and reducing costs, this new coating has the potential to enhance the military mission. Tests show that the tantalum-tungsten-lined gun barrels last three times as long as the chrome-plated tubes. This increased performance provides the basis for the development of more effective weapons in the future.

For this work, Mr. Miller received a Project-of-the-Year award at the annual Partners in Environmental Technology Technical Symposium & Workshop held November 30 – December 2, 2010, in Washington, D.C.

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