Materials science researchers working at the Energy Department's Sandia National Laboratory have created a platinum-gold alloy that they say could be one of the most wear-resistant metals in the world.

They say the alloy is 100 times more durable than high-strength steel, placing it in the same class as diamond and sapphire. Sandia’s team recently reported their findings in Advanced Materials.

The researchers say that although metals are typically thought of as strong, when they repeatedly rub against other metals, like in an engine, they wear down, deform and corrode unless they have a protective barrier, like additives in motor oil.

In electronics, moving metal-to-metal contacts receive similar protections, with outer layers of gold or other precious metal alloys. But these coatings are expensive and they wear out as connections press and slide across each other.

With Sandia’s platinum-gold coating, a single layer of atoms would be lost after a mile of skidding on a set of hypothetical automobile tires made out of the material. The coating could save the electronics industry more than $100 million a year in materials alone, the researchers claim.

The combination of 90 percent platinum with 10 percent gold isn’t new, but the engineering is. The Sandia team proposed a new theory that says wear is related to how metals react to heat, not their hardness, and they then handpicked metals, proportions and a fabrication process that could prove their theory.

“Many traditional alloys were developed to increase the strength of a material by reducing grain size,” said John Curry, a postdoctoral appointee and first author on the paper. But in the presence of extreme stresses and temperatures many alloys will coarsen or soften, especially under fatigue. The researchers saw that with their platinum-gold alloy, the mechanical and thermal stability was excellent, and they did not see much change to the microstructure over long periods of cyclic stress.

In a separate paper published in Carbon, the Sandia team describes the results of an accident. They say that while measuring wear on their platinum-gold, an unexpected black film started forming on top. They recognized it as diamond-like carbon, a man-made coating that is as slick as graphite and hard as diamond. They say their creation was making its own lubricant.

Sandia National Laboratories is operated by National Technology and Engineering Solutions of Sandia LLC, a unit of Honeywell International Inc.