A team led by researchers from Tokyo Metropolitan University has come up with an innovative method for coating magnesium alloys to enhance their corrosion resistance. Rather than relying on expensive and slow vacuum coating methods, they are utilizing a liquid-based chemical process combined with cavitation bubbles.

This thick coating significantly improved resistance to chlorides and bolstered the material’s mechanical properties. The new approach aims to reinforce lightweight materials used in various applications.

The research has been published in the journal Surface and Coatings Technology.

As the automotive industry prepares for a shift toward electric vehicles, advancements in materials are essential to develop lighter components that enable longer distances on the same battery charge.

Magnesium alloys are key players in this shift due to their lightweight properties, being the least dense of all practical metals. However, concerns about their susceptibility to corrosion from salts and other mechanical drawbacks remain.

While magnesium composites have been suggested as alternatives, they are often costly and complicated to produce.

Coating traditional magnesium alloys is another strategy, commonly referred to as plating. However, many methods in plating can take time and result in weak bonds between the original material and the coating.

Additionally, many of these methods often require a vacuum environment, which not only adds to costs but usually involves high temperatures that can be impractical for magnesium, given its low melting point.

This led Assistant Professor Masataka Ijiri and his team to explore chemical conversion coatings, where surfaces are treated with a liquid solution. While these methods are generally cheaper, they typically produce thin layers that do not provide adequate corrosion protection.

During their experiments in water, the team discovered that introducing cavitation—where bubbles form and violently collapse—helped produce thicker films of magnesium phosphate on the surface.

Both techniques they examined, using water jet peening and a multifunctional method incorporating ultrasound waves, resulted in strong protective layers that provided much better corrosion resistance than treatments applied using liquid alone, as confirmed by electrochemical testing.

Although using complete magnesium composite parts may yield excellent results, the expense of such materials necessitates a method that selectively and effectively coats more affordable magnesium alloys, making it a more viable option for industry.

This technology promises significant advancements in creating better materials for the future of electric vehicles.