Safer metal alloys may replace chrome coatings on bathroom fixtures, car bumpers

Published: Thursday, May 21, 2009, 15:22 [IST]
 

Washington, May 21 (ANI): Scientists have now found safer metal alloys to replace chrome coatings, which provides that shiny lustre to metal products like bathroom fixtures and car bumpers.

Researchers at the Massachusetts Institute of Technology (MIT) say that chrome not only adds beauty and durability, but could also be dangerous for workers during manufacturing and also pollutes the environment.

"People have been trying to replace it for a very long time. The problem is that it's the only plated metal coating that has all of these properties - hardness, long-lasting shine and corrosion protection," said Christopher Schuh, MIT associate professor of materials science and engineering.

But the researchers have now developed a new nickel-tungsten alloy that is not only safer than chrome but also more durable.

The new coating, which is now being tested on the bumpers of a truck fleet, could also replace chrome in faucet fixtures and engine parts, among other applications.

The technique used to coat metal objects with chrome-electroplating-involves running a current through a liquid bath of chromium ions, which deposits a thin layer of chrome on the surface of an object placed in the bath.

The ions, known as hexavalent chromium, are carcinogenic if inhaled, and contact with the liquid can be fatal.

Hexavalent chromium can pollute groundwater, and some of the original Superfund cleanup sites involved hexavalent chromium pollution.

"It's an environmental nightmare," said Schuh.

Chrome owes its hardness to its nanocrystalline structure, and thus the researchers decided to duplicate that structure with a material that could be easily and safely electroplated.

They used computer models to predict material properties, and settled on a nickel-tungsten alloy that is environmentally friendly and more durable than chrome.

The researchers have shown that nickel-tungsten alloys remain stable indefinitely at room temperature, and are highly resistant to decomposition when heated.

They can also be made harder and longer lasting than chrome and also the electroplating process is more efficient than that for chrome, because multiple layers can be applied in one step, which could save money for manufacturers.

"Not only do you get rid of the environmental baggage but you make a better product as well," said Schuh.

The technology could be used to coat products like shock absorbers, print rolls and even electronics. (ANI)

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