Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Paint Absorbs Corrosion-causing Chemicals, Kitty-litter Style

25.08.2004


Engineers at Ohio State University have incorporated clay and other chemicals into a paint that keeps metal from corroding -- and reveals when an airplane, boat, or bridge needs to be repainted.



Though the paint is still under development, early tests have shown that it prevents corrosion just as well as commercial paints that are less environmentally friendly.

The new paint is unique because its pigment contains tiny particles of clay that capture the chemicals that cause corrosion. It also releases just the right amount of a corrosion-fighting agent when needed, explained Rudolph Buchheit, professor of materials science and engineering. “It works kind of like high-tech kitty litter,” he said.


With further development, the pigment could enable maintenance crews to inspect surfaces using a common X-ray technique to determine when they need to be repainted. Buchheit and doctoral student Santi Chrisanti described the project Monday, August 23, at the meeting of the American Chemical Society in Philadelphia.

The pigment contains cerium, one of several natural anti-corrosion minerals known as rare earth elements. Coatings inside self-cleaning ovens often contain cerium, but those coatings are passive -- they release cerium continually until the element is gone. Scientists have been working for years to create “smart pigments” that can do more.

“The challenge has been how to keep these rare earth elements stored in a paint and then release them on demand, just when conditions are right for corrosion,” Buchheit said.

Chloride is the chemical responsible for most metal corrosion. Water is another key ingredient, and water that contains salt, or sodium chloride, is particularly corrosive. When paint cracks or wears off, a chemical reaction with the chloride eats away the exposed metal -- a serious problem for critical structures on vehicles or bridges.

To fight corrosion, the new pigment absorbs chloride, and releases cerium or other corrosion inhibitors to form a protective film over cracks in the paint. In tests, the engineers coated pieces of metal with the new paint formulation, and scratched the surface to simulate severe paint wear. Then they subjected the metal to a constant saltwater fog in a laboratory corrosion chamber.

After 1,000 hours, the metal remained corrosion-free -- a performance comparable to commercial paints.

But those commercial paints prevent corrosion using chromate -- a toxic chemical that rose to public awareness with the release of the film Erin Brockovich. Chromate must be carefully disposed of, to keep it from entering the water supply.

And if cerium or other another corrosion inhibitor were to enter the water supply? Buchheit admits that is a question better left to toxicologists than materials scientists, but to his knowledge the chemicals he is studying do not appear to pose the same health hazards.

In another result of their laboratory tests, the engineers confirmed that a technique called X-ray diffraction can be used to measure how much cerium was released to fill the cracks, and how much was left in the paint -- an indicator of whether a piece of metal would need to be repainted.

With this technique, X-rays bounce off of the crystalline clay additives to form a pattern. Because the pattern is unique to every material, scientists can use X-ray diffraction to read a substance’s chemical fingerprint.

Buchheit pointed out that the use of a different X-ray technique, X-ray radiography, is now routine for studying airplanes, bridges and boats: “We want to make our replacement technology as much like the incumbent technology as we can, so people can use the same expertise and equipment to get the job done. X-ray diffraction is not as common outside of the research laboratory as X-ray radiography, but it’s not unprecedented, either.”

He envisions that maintenance crews would set up an X-ray diffraction machine on a rack that rolled over an object, such as an airplane wing. The process could be automated.

The engineers continue to work on the pigment, which should work with just about any corrosion inhibitor, not just cerium. Other possibilities that Buchheit’s team are currently studying include molybdenum and vanadium. Buchheit emphasized, however, that the new pigment is far from a commercial product. “Real corrosion-resistant paints are highly engineered,” he said. “They’ve been given all kinds of additives to make them flow better or to give them a fine gloss -- things we haven’t yet worried about.”

The Air Force Office of Scientific Research funded this work.

| newswise
Further information:
http://www.osu.edu

More articles from Materials Sciences:

nachricht New biomaterial could replace plastic laminates, greatly reduce pollution
21.09.2017 | Penn State

nachricht Stopping problem ice -- by cracking it
21.09.2017 | Norwegian University of Science and Technology

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>