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Sandia National Laboratories researchers Michael Chandross, left, and Nic Argibay show a computer simulation used to predict the unprecedented wear resistance of their platinum-gold alloy, and an environmental tribometer used to demonstrate it. (Photo by Randy Montoya)
A new metal alloy that exhibits superior durability could enable longer-lasting electronics.
Researchers from the U.S. Department of Energy’s Sandia National Laboratories have designed a new platinum-gold alloy that could end up being the most wear-resistant metal in the world, 100 times more durable than high-strength steel.
“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,” materials scientist Nic Argibay, an author on the paper, said in a statement.
While metals are generally strong, they tend to wear down, deform and corrode when they repeatedly rub against other metals, such as in an engine.
In electronics, moving metal-to-metal contacts receive similar protections with outer layers of gold or other precious metal alloys, but they also tend to wear out as connections press and slide across each other constantly.
These negative impacts are often worse the smaller the connections are because there is less material to start with.
However, the new platinum gold coating only loses a single layer of atoms after a mile of skidding on hypothetical tires, meaning that it could possibly significantly extend the lifetime of tires.
“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,” materials scientist Nic Argibay, an author on the paper, said in a statement.
In the new study, the researchers proposed that wear is related to how metals react to heat, not their hardness, which scientists have long believed.
“Many traditional alloys were developed to increase the strength of a material by reducing grain size,” John Curry, a postdoctoral appointee at Sandia and first author on the paper, said in a statement. “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,” he added.
To discover the new alloy, the researchers conducted simulations to calculate how individual atoms affected large-scale properties of a material—a connection that isn’t obvious from observations.
“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,” coauthor Michael Chandross said in a statement.
The team also discovered by chance, a diamond-like carbon forming on top of the alloy that could be harnessed to improve the performance of the alloy and result in a simpler, cheaper way to mass-produce premium lubricant.
“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.”
According to Argibay, the new alloy could save the electronics more than $100 million a year in materials and make electronics more cost-effective, longer-lasting and dependable in a number of applications, including aerospace systems, wind turbines, microelectronics for cell phones and radar systems.
The alloy study was published in Advanced Materials, while the separate carbon-film study was published in Carbon.
