Scientists find a way to make oxidation good for metals on a small scale

It is well known that some metals can oxidize, corrode, form rust and deteriorate the material when exposed to air. But scientists have discovered that oxidation can actually be beneficial for metals at the nanometer scale.

A research team from mainland China, Hong Kong and Taiwan has developed an oxidized nanomaterial that is said to be superelastic.

This means the metal can recover from deformation, and researchers say it could be used to kill bacteria and viruses, protect artifacts, and even make wearable medical devices.

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“We have experimentally demonstrated that metallic glass nanotubes are superelastic at room temperature and outperform a variety of previously known superelastic metals and alloys,” they wrote in a peer-reviewed academic journal. This is stated in a paper published in Nature Materials in December.

“This unique property of metallic glass nanostructures is useful and may find many applications in future nanodevices operating in harsh environments, such as sensors, medical devices, micro- and nanorobots, springs, and actuators.” .”

The research was a multi-year collaboration carried out by a team from the City University of Hong Kong, the Chinese Academy of Sciences, the Beijing Center for Computational Science, the National Taiwan University of Science and Technology, and Shenzhen University.

Many metals react with oxygen, with the exception of silver, platinum, and gold. For example, iron oxide, commonly known as rust, is formed when iron comes into contact with oxygen and water. Therefore, keeping your storage area dry is one way to prevent iron and steel tools from rusting.

Lead author Yang Yong, a professor in CityU’s Department of Mechanical Engineering, said the team’s findings go against the conventional wisdom that oxidation only harms metals.

“When metals are fabricated into shapes tens of nanometers thick, oxidation triggers the formation of a penetrating oxide network, resulting in superelasticity,” Yang said.

A nanometer is one billionth of a meter. Roughly speaking, the width of a human hair is approximately 80,000 to 100,000 nanometers, while the Sars-CoV-2 virus has a diameter of approximately 80 nanometers.

Yang said there may be applications for oxidized nanomaterials that take advantage of various metallic properties, such as using copper oxide’s antimicrobial properties to kill bacteria and viruses.

“Because nanoparticles are small enough to be eaten, nanoscale metals are more effective at killing bacteria than larger sized metals,” he says.

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Yang said the material can also be used as a protective film that can be applied to artifacts to prevent them from being exposed to the air.

He said the material is very stable because it’s already oxidized, and no adhesive is needed to hold the film to the surface. Its oxidation process can be controlled to determine its color.

“Nanocopper can be purplish-red or green, just like the Statue of Liberty in the United States,” he said. The New York statue is made of copper, which has turned green due to years of oxidation.

For medical devices, Yang said the thin material could be applied to the skin, teeth or brain, and could be used to assist during surgery or for research purposes.

He said the cost of manufacturing nanomaterials is low because the use of raw materials is kept to a minimum.