Nanotechnology Now

Our NanoNews Digest Sponsors


Heifer International

Wikipedia Affiliate Button

Home > Press > Rare earth oxides make water-repellent surfaces that last: Ceramic forms of hydrophobic materials could be far more durable than existing coatings or surface treatments

MIT postdoc Gisele Azimi, left, displays three of the 13 different ceramic disks made from oxides of the rare earth elements, with associate professor Kripa Varanasi. Behind them is the furnace used to convert the powdered oxides into solid ceramic form.
Photo: David Castro-Olmedo/MIT
MIT postdoc Gisele Azimi, left, displays three of the 13 different ceramic disks made from oxides of the rare earth elements, with associate professor Kripa Varanasi. Behind them is the furnace used to convert the powdered oxides into solid ceramic form.

Photo: David Castro-Olmedo/MIT

Abstract:
Water-shedding surfaces that are robust in harsh environments could have broad applications in many industries including energy, water, transportation, construction and medicine. For example, condensation of water is a crucial part of many industrial processes, and condensers are found in most electric power plants and in desalination plants.

Rare earth oxides make water-repellent surfaces that last: Ceramic forms of hydrophobic materials could be far more durable than existing coatings or surface treatments

Cambridge, MA | Posted on January 23rd, 2013

Hydrophobic materials — ones that prevent water from spreading over a surface, instead causing it to form droplets that easily fall away — can greatly enhance the efficiency of this process. But these materials have one major problem: Most employ thin polymer coatings that degrade when heated, and can easily be destroyed by wear.

MIT researchers have now come up with a new class of hydrophobic ceramics that can overcome these problems. These ceramic materials are highly hydrophobic, but are also durable in the face of extreme temperatures and rough treatment.

The work, by mechanical engineering postdoc Gisele Azimi and Associate Professor Kripa Varanasi, along with two graduate students and another postdoc, is described this week in the journal Nature Materials. Durability has always been a challenge for hydrophobic materials, Varanasi says — a challenge he says his team has now solved.

Ceramics are highly resistant to extreme temperatures, but they tend to be hydrophilic (water-attracting) rather than hydrophobic. The MIT team decided to try making ceramics out of a series of elements whose unique electronic structure might render the materials hydrophobic: the so-called rare earth metals, which are also known as the lanthanide series on the periodic table.

Since all of the rare earth metals have similar physico-chemical properties, the team expected that their oxides would behave uniformly in their interactions with water. "We thought they should all have similar properties for wetting, so we said, ‘Let's do a systematic study of the whole series,'" says Varanasi, who is the Doherty Associate Professor of Ocean Utilization.

To test this hypothesis, they used powder oxides of 13 of the 14 members of that series (excluding one rare earth metal that is radioactive) and made pellets by compacting and heating them to nearly their melting point in order to fuse them into solid, ceramic form — a process called sintering.

Sure enough, when tested, all 13 of the rare earth oxide ceramics did display strong hydrophobic properties, as predicted. "We showed, for the first time, that there are ceramics that are intrinsically hydrophobic," Varanasi says.

These rare earth oxides "are exotic materials, and interestingly their wetting properties have not been studied," he says, adding that many of the properties of the entire series are not systematically documented in the scientific literature. "This paper also gives a whole host of the properties of rare-earth oxides."

This includes, Azimi says, their morphology, surface chemistry, crystallographic structure, grain structure, sintering temperature and density — yielding "a catalog of information" about how to process and use these materials. The MIT researchers also showed that the materials have greater hardness than many others currently used in rough industrial settings.

Despite their name, rare earth metals are not particularly rare. "Some of them are as abundant as nickel or copper," Azimi says — both of which are widely used industrially.

But separating rare earth metals from the minerals in which they are found can be costly and can leave toxic residues, so their production has been limited. China is currently the world's major supplier of these elements, which have many high-tech applications.

The ceramic forms of rare earth oxides could be used either as coatings on various substrates, or in bulk form. Because their hydrophobicity is an intrinsic chemical property, Azimi says, "even if they are damaged, they can sustain their hydrophobic properties."

To prove the point, the team exposed some of these ceramics to a steam environment, similar to what they would face in a power-plant condenser. Typical polymer-based hydrophobic coatings quickly degrade when exposed to steam, but the ceramics kept their hydrophobicity intact, Varanasi says. The materials sustained their hydrophobicity even after exposure to abrasion, as well as temperatures of 1,000 degrees Celsius, Azimi says

By coating nanotextured surfaces with these ceramics at MIT's Microsystems Technology Laboratories, the team also demonstrated extreme water repellency where droplets bounced off the surface. "These materials therefore provide a pathway to make durable superhydrophobic surfaces as well, and these coatings can be fabricated using existing processes. This makes it amenable to retrofit existing facilities, Azimi says. Such extreme non-wetting properties coupled with durability could find applications in steam turbines and aircraft engines, for example.

Most prior research on hydrophobic materials and coatings has focused on surface textures and structure rather than on their intrinsic chemical properties, Varanasi says. "No one has really addressed the key challenge of robust hydrophobic materials," he says. "We expect these hydrophobic ceramics to have far-reaching technological impact."

Steve Granick, a professor of materials science and engineering and professor of chemistry at the University of Illinois at Urbana-Champaign, who was not connected with this research, says, "This discovery of intrinsic hydrophobicity is exciting and fresh. It's a terrific example of payoff from thinking outside the box."

The research, which included MIT postdoc Rajeev Dhiman and graduate students Hyuk-Min Kwon and Adam Paxson, was supported by the National Science Foundation, the Dupont-MIT Alliance, the MIT Energy Initiative and the Defense Advanced Research Projects Agency.

David L. Chandler, MIT News Office

####

For more information, please click here

Contacts:

Phone: 617-253-2700
Fax: 617-258-8762

Copyright © Massachusetts Institute of Technology

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Unraveling the crystal structure of a -70° Celsius superconductor, a world first: Significant advancement in the realization of room-temperature superconductors August 25th, 2016

Stretchy supercapacitors power wearable electronics August 25th, 2016

AIM Photonics Announces Release of Process Design Kit (PDK) for Integrated Silicon Photonics Design August 25th, 2016

Semblant to Present at China Mobile Manufacturing Forum 2016 August 25th, 2016

Govt.-Legislation/Regulation/Funding/Policy

Analog DNA circuit does math in a test tube: DNA computers could one day be programmed to diagnose and treat disease August 25th, 2016

New approach to determining how atoms are arranged in materials August 25th, 2016

Johns Hopkins scientists track metabolic pathways to find drug combination for pancreatic cancer August 25th, 2016

New electrical energy storage material shows its power: Nanomaterial combines attributes of both batteries and supercapacitors August 25th, 2016

Nanomedicine

Nanofiber scaffolds demonstrate new features in the behavior of stem and cancer cells August 25th, 2016

Johns Hopkins scientists track metabolic pathways to find drug combination for pancreatic cancer August 25th, 2016

50 years after the release of the film 'Fantastic Voyage,' science upstages fiction: Science upstages fiction with nanorobotic agents designed to travel in the human body to treat cancer August 25th, 2016

Tunneling nanotubes between neurons enable the spread of Parkinson's disease via lysosomes August 24th, 2016

Discoveries

Unraveling the crystal structure of a -70° Celsius superconductor, a world first: Significant advancement in the realization of room-temperature superconductors August 25th, 2016

Stretchy supercapacitors power wearable electronics August 25th, 2016

Johns Hopkins scientists track metabolic pathways to find drug combination for pancreatic cancer August 25th, 2016

New electrical energy storage material shows its power: Nanomaterial combines attributes of both batteries and supercapacitors August 25th, 2016

Announcements

Analog DNA circuit does math in a test tube: DNA computers could one day be programmed to diagnose and treat disease August 25th, 2016

Silicon nanoparticles trained to juggle light: Research findings prove the capabilities of silicon nanoparticles for flexible data processing in optical communication systems August 25th, 2016

Johns Hopkins scientists track metabolic pathways to find drug combination for pancreatic cancer August 25th, 2016

New electrical energy storage material shows its power: Nanomaterial combines attributes of both batteries and supercapacitors August 25th, 2016

Military

New electrical energy storage material shows its power: Nanomaterial combines attributes of both batteries and supercapacitors August 25th, 2016

Nanoparticles that speed blood clotting may someday save lives August 23rd, 2016

Curbing the life-long effects of traumatic brain injury August 19th, 2016

Lab team spins ginger into nanoparticles to heal inflammatory bowel disease August 19th, 2016

Energy

New electrical energy storage material shows its power: Nanomaterial combines attributes of both batteries and supercapacitors August 25th, 2016

Lehigh engineer discovers a high-speed nano-avalanche: New findings published in the Journal of Electrochemical Society about the process involving transformations in glass that occur under intense electrical and thermal conditions could lead the way to more energy-efficient glas August 24th, 2016

New flexible material can make any window 'smart' August 23rd, 2016

Researchers reduce expensive noble metals for fuel cell reactions August 22nd, 2016

Water

SLAC, Stanford gadget grabs more solar energy to disinfect water faster: Plopped into water, a tiny device triggers the formation of chemicals that kill microbes in minutes August 15th, 2016

New method for making green LEDs enhances their efficiency and brightness July 30th, 2016

Dirty to drinkable: Engineers develop novel hybrid nanomaterials to transform water July 28th, 2016

New nontoxic process promises larger ultrathin sheets of 2-D nanomaterials July 27th, 2016

Automotive/Transportation

Researchers reduce expensive noble metals for fuel cell reactions August 22nd, 2016

Researchers watch catalysts at work August 19th, 2016

Stanford-led team reveals nanoscale secrets of rechargeable batteries August 8th, 2016

New X-Ray microscopy technique images nanoscale workings of rechargeable batteries: Method developed at Berkeley Lab's Advanced Light Source could help researchers improve battery performance August 7th, 2016

Industrial

New flexible material can make any window 'smart' August 23rd, 2016

Industrial Nanotech, Inc. Provides Shareholder Update August 22nd, 2016

Let's roll: Material for polymer solar cells may lend itself to large-area processing: 'Sweet spot' for mass-producing polymer solar cells may be far larger than dictated by the conventional wisdom August 12th, 2016

Quantum dots with impermeable shell: A powerful tool for nanoengineering August 12th, 2016

Construction

New flexible material can make any window 'smart' August 23rd, 2016

Cement design should take into account the water confined in the smallest pores: A researcher at the UPV/EHU-University of the Basque Country is participating in the study of the stresses of confined water in the micropores of cement at extreme temperatures August 11th, 2016

Nothing -- and something -- give concrete strength, toughness: Rice University scientists show how voids, particles sap energy from cracks August 8th, 2016

Lucintel identifies and prioritizes opportunities for alumina trihydrate (ATH) fillers in the global composites industry August 3rd, 2016

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







Car Brands
Buy website traffic