Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Super-slick material makes steel better, stronger, cleaner

20.10.2015

Harvard researchers design most durable anti-fouling material to date

Steel is ubiquitous in our daily lives. We cook in stainless steel skillets, ride steel subway cars over steel rails to our offices in steel-framed building. Steel screws hold together broken bones, steel braces straighten crooked teeth, steel scalpels remove tumors. Most of the goods we consume are delivered by ships and trucks mostly built of steel.


Surface coating scratched with stainless tweezers, screw driver and diamond pen. The coating, made from rough nanoporous tungsten oxide, is capable of repelling any kind of liquid even after sustaining intense structural abuse.

Credit: Aizenberg Lab/Harvard SEAS

While various grades of steel have been developed over the past 50 years, steel surfaces have remained largely unchanged -- and unimproved. The steel of today is as prone as ever to the corrosive effects of water and salt and abrasive materials such as sand. Steel surgical tools can still carry microorganisms that cause deadly infections.

Now, researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have demonstrated a way to make steel stronger, safer and more durable. Their new surface coating, made from rough nanoporous tungsten oxide, is the most durable anti-fouling and anti-corrosive material to date, capable of repelling any kind of liquid even after sustaining intense structural abuse.

The new material joins the portfolio of other non-stick, anti-fouling materials developed in the lab of Joanna Aizenberg, the Amy Smith Berylson Professor of Materials Science and core faculty member of the Wyss Institute for Biologically Inspired Engineering at Harvard University. Aizenberg's team developed Slippery Liquid-Infused Porous Surfaces in 2011 and since then has demonstrated a broad range of applications for the super-slick coating, known as SLIPS. The new SLIPS-enhanced steel is described in Nature Communications.

"Our slippery steel is orders of magnitude more durable than any anti-fouling material that has been developed before," said Aizenberg. "So far, these two concepts - mechanical durability and anti-fouling - were at odds with each other. We need surfaces to be textured and porous to impart fouling resistance but rough nanostructured coatings are intrinsically weaker than their bulk analogs. This research shows that careful surface engineering allows the design of a material capable of performing multiple, even conflicting, functions, without performance degradation."

The material could have far-ranging applications and avenues for commercialization, including non-fouling medical tools and devices, such as implants and scalpels, nozzles for 3D printing and, potentially, larger-scale applications for buildings and marine vessels.

The biggest challenge in the development of this surface was to figure out how to structure steel to ensure its anti-fouling capability without mechanical degradation. The team solved this by using an electrochemical technique to grow an ultrathin film of hundreds of thousands of small and rough tungsten-oxide islands directly onto a steel surface.

"If one part of an island is destroyed, the damage doesn't propagate to other parts of the surface because of the lack of interconnectivity between neighboring islands," said Alexander B. Tesler, former postdoctoral fellow at SEAS, current research fellow at Weizmann Institute of Science in Israel and the paper's first author. "This island-like morphology combined with the inherent durability and roughness of the tungsten oxide allows the surface to keep its repellent properties in highly abrasive applications, which was impossible until now."

Electrochemical deposition is already a widely used technique in steel manufacturing, said Aizenberg.

"I don't want to create another line that would cost millions and millions of dollars and that no one would adopt," Aizenberg said. The goal, she said, is to be scalable, but not disruptive to current industry practices.

The team tested the material by scratching it with stainless steel tweezers, screwdrivers, diamond-tipped scribers, and pummeling it with hundreds of thousands of hard, heavy beads. Then, the team tested its anti-wetting properties with a wide variety of liquids, including water, oil, highly corrosive media, biological fluids containing bacteria and blood. Not only did the material repel all the liquid and show anti-biofouling behavior but the tungsten oxide actually made the steel stronger than steel without the coating.

Medical steel devices are one of the material's most promising applications, said Philseok Kim, co-author of the paper and co-founder and vice president of technology at SEAS spin-off SLIPS Technologies Inc. "Because we show that this material successfully repels bacteria and blood, small medical implants, tools and surgical instruments like scalpels and needles that require both significant mechanical strength and anti-fouling property are high value-added products we are exploring for application and commercialization," said Kim.

Another avenue for application is functional 3D printing and microarray devices, especially in printing highly viscous and sticky biological and polymeric materials where friction and contamination are major obstacles.

U.S. Navy spends tens of millions of dollars each year dealing with the ramifications of biofouling on hulls. Organisms such as barnacles and algae create drag and increased energy expenditure, not to mention the costs of cleaning and reapplying current anti-fouling paints, most of which are harmful to the environment. If scaled-up, this material could provide a cleaner, more cost-efficient alternative.

"This research is an example of hard core, classic material science," said Aizenberg. "We took a material that changed the world and asked, how can we make it better?"

Leah Burrows | EurekAlert!

Further reports about: Harvard SEAS SLIPS coating material stainless steel surfaces tungsten oxide

More articles from Materials Sciences:

nachricht Serendipity uncovers borophene's potential
23.02.2017 | Northwestern University

nachricht Switched-on DNA
20.02.2017 | Arizona State University

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>