Friday, June 5, 2009

Tungsten: An environmentally friendly solution

A safer way to produce a bright surface

CHROME plating has long been used to show off everything from Harley-Davidson motorcycles to kitchen taps. This is not just because it can be buffed into a shine that you can see your face in. Chrome plating has been cheap to do, it ends up harder than steel and it is extremely durable because it resists corrosion. But working with the stuff can be an environmental nightmare.[...]

To predict which metals would form the nanocrystalline structures that they were searching for, Dr Schuh and his colleagues used computer models that put atoms from different metals together. Because this was done at such a small scale, the way the atoms interact can produce new and different properties according to the rules of quantum physics. They found that when tungsten was added to the nickel it produced a suitable structure. The bonus was that the mixture was capable of being plated and in a way that was more environmentally friendly.

Initial tests showed that when materials were coated in the nickel-tungsten alloy, using a modified electroplating technique that keeps its crystals particularly small, the plating remained stable indefinitely at room temperature. Nor did it easily degrade when exposed to great heat. The nickel-tungsten alloy can be extremely bright and shiny, and even made to become harder than chrome. All in all, its characteristics and absence of environmental hazards make it the most appealing replacement yet found for chrome. The researchers intend to report as much to a forthcoming conference of the National Association for Surface Finishing in Louisville, Kentucky.

Proof, though, will come with use. Testing is already under way, with the nanocrystalline nickel-tungsten alloy being tried out as a plating on the bumpers of a fleet of trucks. It could soon find its way onto kitchen taps and other shiny fixtures. And if it can get to ride on a Harley, then its future will be assured. Read more...

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