Featured Research

from universities, journals, and other organizations

Controlled Corrosion: Researchers Makes The First-ever Atomic-level Observations Of The Corrosion Process, With Implications For Nanostructuring

Date:
February 13, 2006
Source:
Max Planck Society
Summary:
The corrosion of technically relevant alloys, like stainless steel, causes damage that amounts to about 3 percent of the global gross national product. Although this every-day phenomenon has such broad consequences, its fundamental microscopic processes are still largely not understood -- most of all how corrosion begins and develops at an atomic level.

A structural model of a corrosion-induced, 3-atomic-layer thick Au rich film on Cu3Au, protecting the material from further corrosion. The gold atoms are depicted in yellow; the copper atoms, as red balls. Corrosion occurs every day -- and does not even spare the Minerva, the Max Planck Society's icon.
Credit: Image : Max Planck Institute for Metals Research

The corrosion of technically relevant alloys, like stainless steel, causes damage that amounts to about 3 percent of the global gross national product. Although this every-day phenomenon has such broad consequences, its fundamental microscopic processes are still largely not understood -- most of all how corrosion begins and develops at an atomic level.

Now, Andreas Stierle and his colleagues at the Max Planck Institute for Metals Research and the University of Ulm, Germany, as well as the European Synchrotron Radiation Facility (ESRF) in Grenoble, France, have succeeded in observing so-to-speak "live" the atomic processes behind the corrosion of an alloy. To the great surprise of the researchers, despite the destructive nature of the corrosion process, a perfect crystalline protective layer was formed. The scientists were able to determine the layer's structure and chemical composition using highly brilliant synchrotron radiation. Their observations show how technologically relevant alloy surfaces can be nanostructured using targeted corrosion processes (Nature, February 9, 2006).

The scientists from the Max Planck Institute for Metals Research and the European Synchrotron Radiation Facility have chosen an alloy, Cu3Au, whose two components exhibit very different corrosion behaviour. Copper, on the one hand, goes into a solution containing sulphuric acid when confronted even with small corrosion potentials, which yield a voltage between the sample and a reference electrode applied through the electrolyte. Gold, on the other hand, is much more corrosion resistant.

Using highly brilliant synchrotron radiation as a non-destructive, high resolution probe, the scientists have now observed the onset of corrosion in the alloy Cu3Au. They were thus able to do the first-ever analysis of the interface between the liquid electrolyte and the alloy crystal during the corrosion process, with a resolution in the picometre range (10-12 metres, 1 nanometre = 1,000 picometres).

If only a little bit of copper is dissolved from the interface, it builds up a crystalline, 3-atom-layer thick, Au-rich passivation layer. The layer protects the surface of the material from further corrosion (see image 1). Interestingly, the passivation layer does not mimic the crystal structure of the substrate one-to-one. The material's border to the electrolyte rather functions like a mirror, which causes the film to develop with a structure that is a twin of the substrate.

If the corrosion potential is increased by changing the voltage between the sample and the reference electrode, the rest of the copper from the protective passivation layer is dissolved, and the remaining gold atoms form gold islands about 2 nanometres high, which no longer completely cover the surface (see image 2). This process, also called dewetting, is already known in nature, when raindrops come together on a leaf. The corrosion progresses now on the Cu3Au surface, which is directly in contact with the electrolyte. This creates a foam-like, porous structure .

Materials scientists can use these results to understand that it is possible to optimise surface passivation in alloys by setting the corrosion potential above the surface in such a way that a passivation layer is created. Furthermore, controlled corrosion is, at higher potentials, an elegant method of chemically structuring material surfaces at nanometric scales. If the corrosion continues further, eventually a nanoporous gold film is formed, which can be e.g. potentially used as a catalyst because of its very large surface area.



Story Source:

The above story is based on materials provided by Max Planck Society. Note: Materials may be edited for content and length.


Cite This Page:

Max Planck Society. "Controlled Corrosion: Researchers Makes The First-ever Atomic-level Observations Of The Corrosion Process, With Implications For Nanostructuring." ScienceDaily. ScienceDaily, 13 February 2006. <www.sciencedaily.com/releases/2006/02/060213092129.htm>.
Max Planck Society. (2006, February 13). Controlled Corrosion: Researchers Makes The First-ever Atomic-level Observations Of The Corrosion Process, With Implications For Nanostructuring. ScienceDaily. Retrieved September 1, 2014 from www.sciencedaily.com/releases/2006/02/060213092129.htm
Max Planck Society. "Controlled Corrosion: Researchers Makes The First-ever Atomic-level Observations Of The Corrosion Process, With Implications For Nanostructuring." ScienceDaily. www.sciencedaily.com/releases/2006/02/060213092129.htm (accessed September 1, 2014).

Share This




More Matter & Energy News

Monday, September 1, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Australian Airlines Relax Phone Ban Too

Australian Airlines Relax Phone Ban Too

Reuters - Business Video Online (Aug. 26, 2014) Qantas and Virgin say passengers can use their smartphones and tablets throughout flights after a regulator relaxed a ban on electronic devices during take-off and landing. As Hayley Platt reports the move comes as the two domestic rivals are expected to post annual net losses later this week. Video provided by Reuters
Powered by NewsLook.com
Hurricane Marie Brings Big Waves to California Coast

Hurricane Marie Brings Big Waves to California Coast

Reuters - US Online Video (Aug. 26, 2014) Huge waves generated by Hurricane Marie hit the Southern California coast. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Chinese Researchers Might Be Creating Supersonic Submarine

Chinese Researchers Might Be Creating Supersonic Submarine

Newsy (Aug. 26, 2014) Chinese researchers have expanded on Cold War-era tech and are closer to building a submarine that could reach the speed of sound. Video provided by Newsy
Powered by NewsLook.com
Breakingviews: India Coal Strained by Supreme Court Ruling

Breakingviews: India Coal Strained by Supreme Court Ruling

Reuters - Business Video Online (Aug. 26, 2014) An acute coal shortage is likely to be aggravated as India's supreme court declared government coal allocations illegal, says Breakingviews' Peter Thal Larsen. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins