Researchers from the Korea Maritime and Ocean University (KMOU) (Busan, South Korea) recently developed a new aluminum-magnesium-silicon (Al-Mg-Si) alloy that can greatly increase the corrosion resistance of steel. This protective anticorrosion coating, specifically designed for ships in marine and coastal facilities and structures, is projected to increase the economic life and durability of steel machinery in an environmentally friendly manner.
The KMOU research team recently published a study of their anticorrosion alloy coating in the November 2021 issue of Corrosion Science.
“When I served in the navy, I was constantly looking at rusting machinery. Since then, I have become fully engaged in research on how to produce better anti-corrosive steels,” says Prof. Myeong-Hoo Lee of KMOU, who led the study.
One of the most common methods of improving the corrosion resistance of steel is coating it with other metals such as aluminum (Al). But the use of Al in marine applications is limited due to its tendency to corrode when it interacts with chloride ions in seawater. The addition of elements such as magnesium (Mg) and silicon (Si) is able to form an alloyed coating—however, Mg cannot be easily deposited as a coating using conventional methods of dipping steel in a hot bath of metal salts.
In the KMOU-led study, researchers took aluminized steel with Al and Si and plated it with Mg using a technique called physical vapor deposition. After exposing the coating to a high temperature of 375 °C (707 °F), the research team characterized the coating film and performed corrosion testing in the form of a salt spray test.
The researchers found that the corrosion products formed in two layers: a surface layer made primarily of Al-based corrosion products and an inner corrosion layer made up of Al-, Mg-, and Si-based products. Moreover, the inner layer of corrosion products produced a “shielding effect,” which further improved their anticorrosion properties.
“Our research reveals how a highly corrosion-resistant steel can be produced using a simple change in the surface treatment protocol. This makes it very meaningful for conserving energy and environmental resources,” explains Prof. Lee.
Source: KMOU Research News, www.kmou.ac.kr.