Materials

Flexible alloy prevents steel corrosion and repairs itself when damaged

Flexible alloy prevents steel ...
A Rice University scientists applies a novel coating to steel to protect against corrosion
A Rice University scientists applies a novel coating to steel to protect against corrosion
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A Rice University scientists applies a novel coating to steel to protect against corrosion
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A Rice University scientists applies a novel coating to steel to protect against corrosion
Rice University graduate student M.A.S.R. Saadi applies the novel coating to a piece of mild steel
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Rice University graduate student M.A.S.R. Saadi applies the novel coating to a piece of mild steel

Scientists at Rice University have cooked up a new alloy with a unique and diverse set of attributes that could prove highly effective at protecting steel from corrosion. The novel coating not only prevented rusting in submerged slabs of common steel, but is flexible and proved capable of healing itself when damaged.

The new anti-corrosion coating is made of a lightweight sulfur-selenium alloy, and according to the material scientists behind it, combines desirable qualities from currently available solutions. This means an ability to block moisture and chlorine like zinc- and chromium-based coatings, an ability to protect steel under seawater-like conditions like polymer-based coatings, and an ability to fend off microbe-induced corrosion.

This was established through a series of experiments, the first of which saw small slabs of common mild steel coated with sulfur-selenium alloy and submerged in seawater for a month, along with an uncoated slab of steel as a control. While the bare steel rusted significantly, the coated steel exhibited no change in color and proved highly resistant to oxidation.

Next, the scientists tested it out against sulfate-reducing bacteria that is known to greatly accelerate the corrosive process. Coated and uncoated samples were exposed to plankton and biofilms, and again the alloy helped to protect the steel underneath. According to the scientists, the coating offered an "inhibition efficiency" of 99.99 percent.

Perhaps most impressively, the team found the alloy to have powerful self-healing properties. When a film of it was cut in half and the two pieces were placed next to each other on a hot plate, they reformed into a single, foldable film within two minutes when heated to 70 °C (158 °F). Pinholes could also be repaired by heating the material to 130 °C (266 °F) for 15 minutes, with the healed material proving just as effective at protecting steel as undamaged, original coatings.

“If you give the alloy a poke, it recovers,” says study author Muhammad Rahman. “If it needs to recover quickly, we assist it using heat. But over time, most thick samples will recover on their own.”

Rice University graduate student M.A.S.R. Saadi applies the novel coating to a piece of mild steel
Rice University graduate student M.A.S.R. Saadi applies the novel coating to a piece of mild steel

Flexible in nature, the scientists see the new alloy not just serving as a protective coating for steel infrastructure in and around watery environments, but in bendable electronics too. On this, they report that alloy to be a better insulator than most flexible materials, while also being more flexible than most insulating materials. They are now continuing to experiment with varieties of the material to suit different types of steel and explore different coating techniques.

“The first target is structures, but we’re aware the electronics industry faces some of the same problems with corrosion,” says study author Pulickel Ajayan. “There are opportunities.”

The research was published in the journal Advanced Materials

Source: Rice University

7 comments
7 comments
Chris Coles
Such a new form of treatment for steel freight containers would transform the freight industry, pipelines above and below ground . . . the list is endless.
paul314
What are the environmental considerations? Does this stuff have longterm effects on creatures it's not supposed to inhibit? Selenium is toxic to waterfowl (and of course humans in higher concentrations) but maybe the alloy is stable enough to avoid those issues
Username
Since the alloy is used as a coating, how scratch resistant is it?
noteugene
If a coating like this will work on SS, wonder if a similar application could be used on pig iron for the purpose of strengthening concrete?
Calcfan
Does this reported new alloy have a name, or even a group name?
jerryd
Corten Steel does that without a coating 50 yrs ago.
Eggster
How would this fair against barnacles and mussels?