A new platinum-gold alloy with extreme wear resistance shows promise in the electronics sector and beyond, potentially paving the way for other spinoffs based on the science behind the discovery, materials scientists said.

The technology has not been commercialized yet, but expectations are high that it could fill metal-coating niches, given its remarkable performance in the laboratory. It is said to be 100 times more durable than high-strength steel and ranks among the most wear-resistant materials such as diamonds and sapphires.

A team of scientists at Sandia National Laboratories, a U.S. government lab, produced the platinum-gold alloy and outlined the discovery to the public in mid-August.

The alloy can take a lot of punishment, standing up to friction far better than many other materials. Christopher Schuh, head of the Department of Materials Science and Engineering at the Massachusetts Institute of Technology, cast Sandia's findings as groundbreaking, with potential for commercial applications.

"It's a very convincing piece of work," said Schuh, who also founded Xtalic Corp., a company that specializes in metal alloys used in electronic connectors.

Schuh was not involved with the Sandia research.

"What they've shown is that when we make a stable nanostructure in platinum, it has an exceptional wear property," he said.

Superalloy?

Precious metal alloys are nothing new in electronics. They are widely used in applications such as connectors where resistance to wearing, conductivity and stability are important properties.

But by arranging atoms in a novel way, Sandia scientists supercharged its wear resistance, among other properties.

Nic Argibay, a Sandia materials scientist on the team that made the discovery, said modeling metal properties based on evolving theories pointed to platinum and gold having microstructural characteristics that would prove extremely wear resistant and stable, more so than other metal combinations. Subsequent lab tests of the alloy served as proof of concept.

"And in a nutshell, that really is stable nanocrystallinity," Argibay said.

Stable is a keyword here. It is one thing to identify a material as wear resistant, but for it to be broadly useful in many applications, it has to stay that way after repeated use.

"It's sort of a Holy Grail everyone in the community of metallurgists strive towards. We've known for many years that nanocrystalline entities are useful, [but the] problem is, how do you retain it?" Argibay said, referring to stability.

Schuh made a similar point. One key issue in making advances in materials science is that nature does not let you arrange atoms easily, he said. However, techniques are becoming more sophisticated, leading to more desirable properties, particularly stability.

"I like to say the basic goal is to put every atom in the right place," Schuh said.

The platinum-gold alloy was made using relatively straightforward processes with potential for bulk production techniques that could help drive down costs, Argibay said. "There's nothing very unconventional about how we synthesize it or what processes we used."

Eyeing applications

If the team's findings prove useful beyond the lab — entailing real-world testing by partnering with manufacturers — it may drive down costs in some electronic applications while improving product life in others.

"We can see that there's very different approaches one might take with a cheap consumer electronic product and a high-tech, billion-dollar device that needs to operate for as long as possible," Argibay said.

Using a superalloy such as this could slash costs by decreasing the use of expensive metals such as platinum and gold. For example, you might get the same performance in a connector, where wear resistance is desired, using about 10 times less platinum and gold, Argibay said.

In other machines, it might boost performance. As a coating on wind turbine parts or in satellites, it could help decrease maintenance frequency and extend product life. Argibay also wondered if the alloy might open up possibilities in microcomputing by increasing the durability of switches at a smaller scale than is now feasible.

"And we have seen some excitement in the community," Argibay said, referring to microcomputing.

Part of Schuh's optimism about the discovery stems from the superalloy's potential to address these kinds of real-world issues. "Many of the commercial successes in stable nanocrystalline metals that I've been affiliated with almost all hinge on better wear performance."

It often comes down to cost. "It's an industry that spends many billions of dollars a year on precious metals for those finishes," Schuh said. "If you can improve the performance, you can use less of that stuff, and that is intrinsically interesting."

The unknown

The platinum-gold alloy also displayed unique characteristics that came as a surprise. During wear tests, the Sandia team found the alloy produced a black film that turned out to be diamond-like carbon. It was hard and slippery.

The implication? It is "self-lubricating," said Michael Chandross, another materials scientist on the Sandia team. That could help the alloy battle friction. It could also be a way to make the special lubricant for other uses.

There is also the question of how the theory might be applied to other metals. The platinum-gold combination proved to be the most wear-resistant among modeled materials, although the Sandia team plans to test other non-precious metal alloys. They might not be at par with the platinum-gold alloy for stability and wear resistance, but they could prove good enough, and cheaper, for other uses.

Argibay pointed to the potential in making more durable ball bearings, among other things. There may also be a green angle. Schuh said scientists are looking for alternatives to chrome, a widely used coating that is "rendered from toxic and carcinogenic chemistries." A stable nano-structured product might open up options to displace chrome, he said.

For the time being, the theories and testing are constrained to the lab. But Argibay said Sandia was considering partnerships with industry.

"There's a value proposition. It's immense," Argibay said. "And then you start to wonder about these emergent properties."