Steel is often coated in other metals to improve its corrosion resistance, but the salty marine environment poses an extra challenge. Aluminum is a common anti-corrosion coating, but it itself tends to react with chloride ions in seawater and rust easily.

So for the new study, engineers at the Korea Maritime and Ocean University (KMOU) developed a new alloy coating made of aluminum, magnesium and silicon (Al-Mg-Si). The team started with aluminized steel, which is steel that has been hot-dipped in a bath of aluminum and silicon to coat it. The missing ingredient – magnesium – can't be applied through this method, so the team coated the steel using physical vapor deposition. Finally, the coating was then exposed to a high temperature of 375 °C (707 °F), for different amounts of time.

The team then tested the corrosion resistance of the new coating by subjecting it to a standard salt spray test. They compared versions of the new alloy that had been heated for zero, five or 30 minutes, as well as a regular aluminized steel sheet and a galvanized steel sheet.