'Poisoning' corrosion brings stainless magnesium closer

August 19, 2013
The aerospace industry is one that could benefit from a breakthrough in reducing the corrosion rate of lightweight metal, magnesium. Credit: iStock

(Phys.org) —In a discovery that could have major implications for the aerospace, automotive and electronics industries, scientists have found a way to dramatically reduce the corrosion rate of lightweight wonder metal magnesium: adding arsenic.

Weighing in at two thirds less than aluminium, is the lightest structural metal. It has many potential , but uptake is severely restricted by its poor resistance to corrosion. Identification of methods to restrict magnesium corrosion is the first step in engineering such technology into functional alloys.

For the first time, a group of researchers, led by Monash University's Associate Professor Nick Birbilis, have created a with significantly reduced corrosion rates by adding a cathodic 'poison' - arsenic.

They found that the addition of very low levels of arsenic to magnesium retards the corrosion reaction by effectively 'poisoning' the reaction before it can complete.

Once magnesium is available in a more stainless, or corrosion-resistant, form wider use will lead to significant weight and in transportation industries. It has been the subject of significant research efforts concentrating on developing light metals.

Associate Professor Birbilis, of the Monash Department of Materials Engineering, said the discovery would contribute to the birth of more 'stainless' magnesium products by exploiting cathodic poisons.

"This is a very important and timely finding. In an era of light-weighting for energy and emissions reductions, there is a great demand for magnesium alloys in everything from to air and land transportation," Associate Professor Birbilis said.

"Magnesium products are rapidly evolving to meet the demands of industry, but presently are hindered by high corrosion rates. The arsenic effect we discovered is now being trialled as a functional additive to existing commercial alloys.

"Our breakthrough will help develop the next generation of magnesium products, which must be more stainless."

The research, conducted with the University of Wales and CSIRO, is published in the journal Electrochemistry Communications.

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More information: www.sciencedirect.com/science/article/pii/S1388248113002804

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8 comments

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Eikka
not rated yet Aug 19, 2013
But..

a) won't it leach arsenic into the environment and create a disposal problem?
b) magnesium burns really well and can't be put out with water or CO2 because it simply strips oxygen off of them and just keeps burning. If you toss water at burning magnesium, you get a jet of burning hydrogen back.

bearly
1 / 5 (4) Aug 19, 2013
If you can "poison" a chemical reaction is Rust "alive" ? lol
javjav
not rated yet Aug 19, 2013
Is it not coming a bit late? The aerospace industry is already replacing aluminium with carbon fiber (Airbus A-380 and new A-320, Boeing Dreamliner ...), carbon fiber is even lighter, stronger, and more durable than magnesium. Sure it may have several applications, but I don't see "major implications for the aerospace" industry.
NikFromNYC
1.7 / 5 (11) Aug 19, 2013
"Weighing in at two thirds less than aluminium...."

Correction A: "Weighting two thirds that of aluminum...."
Correction B: "Weighting a third less than aluminum...."

Steven Jobs' flammable NeXT computer was made of magnesium:
http://gizmodo.co...ter-case
Kiwini
1 / 5 (11) Aug 19, 2013
Is it not coming a bit late? The aerospace industry is already replacing aluminium with carbon fiber (Airbus A-380 and new A-320, Boeing Dreamliner ...), carbon fiber is even lighter, stronger, and more durable than magnesium. Sure it may have several applications, but I don't see "major implications for the aerospace" industry.


There are, however, large possibilities with the automotive folks. Mag's already in use in a lot of cars, but so far most of the applications have been in places that are sheltered from the environment.

If it works, we can expect large-scale production of lighter wheels, brake calipers, body parts, gearcases, engine blocks....
TheGhostofOtto1923
1.5 / 5 (2) Aug 19, 2013
Mag's already in use in a lot of cars, but so far most of the applications have been in places that are sheltered from the environment
One of the first places magnesium was used was in 'mag' wheels. It is currentlly used in the transmission casings of many cars.
Mannstein
5 / 5 (1) Aug 19, 2013
Magnesium was first used in the engine block for the VW Beetle.
GSwift7
5 / 5 (1) Aug 20, 2013
Is it not coming a bit late? The aerospace industry is already replacing aluminium with carbon fiber


Not really. There's currently a move towards composite metals, where you combine mixtures of tiny bits of different metals and other materials to get super-materials with unique properties. They make things like turbine blades this way now. Carbon fiber isn't good at certain types of things, like high temperature, or where you know there's going to be a lot of friction, or in environments where there are harsh chemicals.

More material options is always a good thing, especially if the material has some specific desirable property like low weight. There's never going to be a one-size fits all material for everything.

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