Engineers create most wear-resistant metal alloy in the world

Engineers create most wear-resistant metal alloy in the world
Credit: Sandia National Laboratories

If you're ever unlucky enough to have a car with metal tires, you might consider a set made from a new alloy engineered at Sandia National Laboratories. You could skid—not drive, skid—around the Earth's equator 500 times before wearing out the tread.

Sandia's materials science team has engineered a platinum-gold alloy believed to be the most wear-resistant metal in the world. It's 100 times more durable than high-strength steel, making it the first alloy, or combination of metals, in the same class as diamond and sapphire, nature's most wear-resistant materials. Sandia's team recently reported their findings in Advanced Materials. "We showed there's a fundamental change you can make to some alloys that will impart this tremendous increase in performance over a broad range of real, practical metals," said materials scientist Nic Argibay, an author on the paper.

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 eventually they wear out, too, as connections press and slide across each other day after day, year after year, sometimes millions, even billions of times. These effects are exacerbated the smaller the connections are, because the less material you start with, the less wear and tear a connection can endure before it no longer works.

With Sandia's platinum-gold coating, only a single layer of atoms would be lost after a mile of skidding on the hypothetical tires. The ultradurable coating could save the electronics industry more than $100 million a year in materials alone, Argibay says, and make electronics of all sizes and across many industries more cost-effective, long-lasting and dependable—from aerospace systems and wind turbines to microelectronics for cell phones and radar systems.

"These wear-resistant materials could potentially provide reliability benefits for a range of devices we have explored," said Chris Nordquist, a Sandia engineer not involved in the study. "The opportunities for integration and improvement would be device-specific, but this material would provide another tool for addressing current reliability limitations of metal microelectronic components."

New metal puts an old theory to rest

You might be wondering how metallurgists for thousands of years somehow missed this. In truth, the combination of 90 percent platinum with 10 percent gold isn't new at all.

But the engineering is new. Argibay and coauthor Michael Chandross masterminded the design and the new 21st century wisdom behind it. Conventional wisdom says a metal's ability to withstand friction is based on how hard it is. The Sandia team proposed a new theory that says wear is related to how metals react to heat, not their hardness, and they 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 at Sandia and first author on the paper. "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."

Now they have proof they can hold in their hands. It looks and feels like ordinary platinum, silver-white and a little heavier than pure gold. Most important, it's no harder than other platinum-gold , but it's much better at resisting heat and a hundred times more wear resistant.

The team's approach is a modern one that depended on . Argibay and Chandross' theory arose from simulations that calculated how individual atoms were affecting the large-scale properties of a material, a connection that's rarely obvious from observations alone. Researchers in many scientific fields use computational tools to take much of the guesswork out of research and development.

"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," Chandross said.

A slick surprise

Still, there will always be surprises in science. In a separate paper published in Carbon, the Sandia team describes the results of a remarkable accident. One day, while measuring wear on their platinum-gold, an unexpected black film started forming on top. They recognized it: diamond-like carbon, one of the world's best man-made coatings, slick as graphite and hard as diamond. Their creation was making its own lubricant, and a good one at that.

Diamond-like carbon usually requires special conditions to manufacture, and yet the alloy synthesized it spontaneously.

"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," Curry said. "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."

The phenomenon could be harnessed to further enhance the already impressive performance of the , and it could also potentially lead to a simpler, more cost-effective way to mass-produce premium lubricant.

Explore further

Predicting the limits of friction: Team looks at properties of material

More information: John F. Curry et al. Achieving Ultralow Wear with Stable Nanocrystalline Metals, Advanced Materials (2018). DOI: 10.1002/adma.201802026
Journal information: Advanced Materials , Carbon

Citation: Engineers create most wear-resistant metal alloy in the world (2018, August 16) retrieved 19 September 2019 from
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Aug 17, 2018
Usually in the literature
metal bond is described as implemented
through socialization
external electrons of atoms and not possessing the property
orientation. Although there are attempts (see below) to explain
directed metal bond as the elements crystallize into a certain type of lattice.
In the work
"Nature of chemical elements"
It was shown that the metallic bond in the densest packages (HEK and HCC)
between a centrally chosen atom and its neighbors in the general case,
presumably, is carried out by means of 9 (nine) directed links, in contrast to the number of neighbors equal to 12 (twelve) (coordination number). Probably \ "strange \" three (3) atoms are present in the coordination number 12 stereometrically, and not because of the connection.
The answer should be an experimental test. hfilipen

Aug 17, 2018
So more practical uses for precious metals. More reason to find an asteroid full of them.

Aug 17, 2018
And where did the carbon come from - their breath?

Aug 17, 2018
More reason to find an asteroid full of them.

Attaboy Otto, we will make a Belter out of you yet. BTW, if 16 Psyche actually is the core of a differentiated planetesimal, the amount of recoverable gold and platinum there may be mind blowing.

Aug 17, 2018
Oh well, so much for a Market-Driven economy.

Add it up.
You = hundreds of Kg?
Your hardsuit = ?Kg?
Your habitat = ?Kg?
All your environmental systems and other technology =?Kgs
Your tools such as pickaxe & shovels and drilling gear = ?Kg
Your wisecracking robot wingman & lots of batteries & lube = ?Kg
Don't forget a harmonica.
And your burro + sustenance.
I'm still waiting for any of you Heroic Space Prospectors to post a utube video of you stuffing your burro into his spacesuit!

Don't forget, lots of pb&j sandwiches. I know that canned beans is more authentic to the meme. Butt siriusly? While trapped in a spacesuit?

And a biggley supply of adult diapers. If they're good enough for the trumpster, they're good enough for you!

$$$$s fuel to claw out of Earth orbit & the fuel to rendezvous with an asteroid. That totals up to how much?

How many $ for fuel for a controlled landing of your precious cargo?
& how low will the market price crash upon landing?

Aug 17, 2018
So more practical uses for precious metals. More reason to find an asteroid full of them.

Yet estimates of platinum group metal content in Asteroids appear to be based on their known presence within nickel-iron alloys in meteorites - some samples can exceed 100ppm. As native Platinum at 100ppm in placer deposits on Earth, that would be hugely exciting. As low grade impurities within nickel-iron alloys - not.

Of all possible platinum ores that would be one of the most intractable, because making alloys is easy, but unmaking them is very hard; I doubt they could be economically extracted even here on Earth, without the complications that come with their location. The value of that ore will be no more than that of raw nickel-iron alloy with some interesting impurities.

Believing it will be easy and profitable to make use of asteroid minerals without extraordinary technological advances (or that those advances are easily achievable or inevitable) is... fantasy.

Aug 18, 2018
Back to the subject advances in durability for our technologies seem to often be neglected - I'm pleased to see that isn't entirely the case. Seems like there will be endless applications for wear resistant coatings and these will make what we make more reliable and longer lasting.

Aug 19, 2018
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