Scientists in Japan have discovered a clever way to make lightweight metals stronger and more resistant to rust—by using bubbles.
This breakthrough could help build better electric cars by improving how magnesium alloys are protected, without the need for expensive or complicated equipment.
Led by Assistant Professor Masataka Ijiri from Tokyo Metropolitan University, the research team focused on magnesium alloys.
These metals are some of the lightest used in manufacturing, making them ideal for electric vehicles that need to travel far on limited battery power. But magnesium has a major drawback—it corrodes easily, especially when exposed to salts like those used on roads in winter.
Previous solutions to protect magnesium involved coating it with other materials. However, traditional coating techniques, such as ceramic plating, often require vacuum chambers and high temperatures.
That’s a problem because magnesium melts at relatively low temperatures, and the vacuum-based methods are costly and slow.
Even liquid-based coating methods, which are simpler and cheaper, haven’t worked well because the protective layers they create are too thin to provide good corrosion resistance.
Professor Ijiri’s team came up with a new approach that uses a natural effect called cavitation. Cavitation happens when bubbles form in a liquid and then collapse violently.
This action can be very powerful at a tiny scale, and the team used it to help form a thicker, stronger coating on the surface of magnesium alloys.
In their experiments, they placed magnesium in water mixed with phosphoric acid. Then they used two methods to create cavitation: one by firing strong water jets at the metal (called water jet peening), and another by combining water jets with sound waves (called multifunction cavitation).
These violent bubble bursts helped build up a coating of magnesium phosphate on the surface of the metal.
The result was a much thicker and more even coating than previous methods could achieve. It showed significantly better protection against corrosion when tested in salty conditions. This means that magnesium parts treated with this method could last much longer without rusting, even in harsh environments.
What makes this technology so promising is that it avoids the high costs and complexity of using full magnesium composites or vacuum-based coatings. Instead, it offers a simple, affordable way to strengthen magnesium alloys by adding protective layers exactly where needed.
This breakthrough could make a big difference for electric vehicle makers, allowing them to use lighter materials without worrying about corrosion. In turn, this could help cars go further on a single charge and lower production costs—two key goals in the race to build better electric vehicles.
