Materials

Platinum-gold mix becomes world's most durable metal alloy

Platinum-gold mix becomes worl...
Sandia researchers Michael Chandross (left) and Nic Argibay, overseeing the testing of the platinum-gold alloy that's now the world's most durable alloy
Sandia researchers Michael Chandross (left) and Nic Argibay, overseeing the testing of the platinum-gold alloy that's now the world's most durable alloy
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Sandia researchers Michael Chandross (left) and Nic Argibay, overseeing the testing of the platinum-gold alloy that's now the world's most durable alloy
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Sandia researchers Michael Chandross (left) and Nic Argibay, overseeing the testing of the platinum-gold alloy that's now the world's most durable alloy

Engineers at Sandia National Laboratories have developed what they say is the most durable metal alloy ever created. Made up of a combination of platinum and gold, the new material is apparently 100 times more wear-resistant than high-strength steel, which makes it the first metal alloy to join the same class as diamond. Even better, it naturally produces its own lubricant that, under normal circumstances, is extremely fiddly and expensive to make.

The Sandia alloy is made up of 90 percent platinum and 10 percent gold, and to illustrate how durable it is, the team uses a pretty colorful analogy. Imagine skidding on tires made of the new alloy – according to its inventors, only a single layer of atoms would be worn off after skidding for a mile, and you could drift around the Earth's equator 500 times before the tread would give out.

Interestingly, this particular platinum-gold alloy isn't new, but it had long been overlooked in terms of durability. That's because when engineers are developing or studying tough alloys, they usually look to the harder ones. This alloy isn't particularly hard, but was found to react to heat better, letting it resist damage from friction for longer.

"Many traditional alloys were developed to increase the strength of a material by reducing grain size," says John Curry, first author of the study. "Even still, in the presence of extreme stresses and temperatures many alloys will coarsen or soften, especially under fatigue. We saw that with our platinum-gold alloy the mechanical and thermal stability is excellent, and we did not see much change to the microstructure over immensely long periods of cyclic stress during sliding."

The researchers approached the problem using computer simulations to monitor what individual atoms were doing, and how that affected the overall properties of the material. From there, materials that have particularly desirable traits can be selected for further study, combined and eventually tested in the real world.

"We're getting down to fundamental atomic mechanisms and microstructure and tying all these things together to understand why you get good performance or why you get bad performance, and then engineering an alloy that gives you good performance," says Michael Chandross, co-author of the study.

But there's an even weirder wrinkle to the story. During testing, the researchers realized that a black film had started forming on top of the alloy. This stuff turned out to be diamond-like carbon, an effective lubricant that normally takes a pretty involved and expensive process to create.

"We believe the stability and inherent resistance to wear allows carbon-containing molecules from the environment to stick and degrade during sliding to ultimately form diamond-like carbon," says Curry. "Industry has other methods of doing this, but they typically involve vacuum chambers with high temperature plasmas of carbon species. It can get very expensive."

Not only could this spontaneous production of lubricant help the alloy last even longer, but it could be harnessed as a new, easier way to mass produce diamond-like carbon for other industrial uses.

The research was published in two papers, one appearing in Advanced Materials and the other in the journal Carbon.

Source: Sandia National Laboratories

7 comments
piperTom
The carbon comes "from the environment"? Oh, dear! Much more research needs to be done on That.
TomWatson
How about, " REMINGTON STEELE "?
Gregg Eshelman
An application this seems perfect for but will likely never ever be used on is crankshaft bearings for internal combustion engines. Imagine an engine with all it's turning and sliding surfaces coated with this stuff.
Expanded Viewpoint
If it can be turned into nano sized particles, maybe it could be sold as an oil additive? That would be pretty slick (pun intended!), wouldn't it? Maybe it would be better to plasma spray it onto bearing surfaces in a vacuum chamber or using an inert gas. Brings a whole new meaning to the term "gold plated"! Randy
MD
Gregg Eshelman: That would be terrible.. It would never wear out.. Better charge a premium for that..
Crankie Fahrt
Great! Cannot wait to get my inheritance so that I can afford that new bearing. Too bad two of the most expensive metals are required for this new alloy. Now if only they can meld wood and dirt to create a decent metal...
dougspair
...Now, if we could just manufacture some 'un-obtainium'.... This gold-platinum has been used in jewelry for years...it has already been shown to last a long time.