Nav: Home

Self-healing gold particles

September 14, 2017

Self-healing materials are able to repair autonomously defects, such as scratches, cracks or dents, and resume their original shape. For this purpose, they must be composed of several components whose combined properties result in the desired characteristics. Scientists of the Karlsruhe Institute of Technology (KIT) and the Technion - Israel Institute of Technology now discovered that also tiny particles of pure gold have surprising self-healing capacities.

Lending shape memory to materials is a very complex, painstaking effort. In pure metals, self-healing capacities repairing mechanically caused defects so far have been considered impossible. However, they have now been observed by scientists in pure gold. This is reported in the Advanced Science journal.

"The search for materials of this kind so far has been concentrated on polymers made up of many components and complicated structures," states Christian Brandl of the Institute for Applied Materials - Materials and Biomechanics (IAM-WBM). Their self-healing powers were all based on the collective transformation of the phases of one or more materials making them up. This is caused, for instance, by heating, melting or precipitation, which may change materials properties. In metal alloys, the shape memory effect is based on the phenomenon that they can exist in two different crystal structures as a function of a specific temperature. When this is changed, the metals "remember" their former shape they had at that respective temperature. However, this self-healing effect is never complete in composites or in alloys.

Self-healing or shape memory in pure metals was entirely unknown before. This effect is precisely what a group of scientists around Dr. Christian Brandl (KIT) and Eugen Rabkin of the Technion - Israel Institute of Technology now observed in gold particles. These multi-shaped particles resumed their individual original shapes almost completely. There was no deformation of any kind. "The fascinating thing about this is that the restored particle shapes did not correspond to that with the lowest surface energy, as would have been expected," says Brandl.

The scientists had produced mechanical defects in the particles first in simulations by high-power computers and then, in reality, with the measurement tip of a scanning force microscope. They found that annealing air temperatures far below the melting temperature of gold caused gold atoms to move along surface steps back into the dents, refilling them almost completely. Such surface steps occur in many deformed metals. Consequently, Brandl expects also other metals to have the self-healing properties observed here. The scientists anti-cipate that their findings will allow robust components for structures smaller than one thousandth of a millimeter to be designed.

-end-

https://www.kit.edu/downloads/pi/Self-healing_nanoparticle.mp4

Video description: The video shows how, in molecular dynamics simulation, heating of the deformation first applied (dent) produces random movements of the gold atoms (so-called diffusion) slowly healing back into the original shape. The atoms are stained as a function of their height. In the smaller window, those atoms are darkest which moved over the longest distance, which shows that the atoms move along the surface steps.

For further information, please contact: Dr. Felix Mescoli, Press Officer, Phone: +49 721 608-48120, Fax: +49 721 608-43658, Email: felix.mescoli@kit.edu

More information:https://www.kit.edu/downloads/pi/Self-healing_nanoparticle.mp4

Being „The Research University in the Helmholtz-Association", KIT creates and imparts knowledge for the society and the envi-ronment. It is the objective to make significant contributions to the global challenges in the fields of energy, mobility and infor-mation. For this, about 9,300 employees cooperate in a broad range of disciplines in natural sciences, engineering sciences, economics, and the humanities and social sciences. KIT pre-pares its 26,000 students for responsible tasks in society, indus-try, and science by offering research-based study programs. In-novation efforts at KIT build a bridge between important scien-tific findings and their application for the benefit of society, eco-nomic prosperity, and the preservation of our natural basis of life.

Since 2010, the KIT has been certified as a family-friendly university.

This press release is available on the internet at http://www.sek.kit.edu/presse.php

Karlsruher Institut für Technologie (KIT)

Related Technology Articles:

How technology use affects at-risk adolescents
More use of technology led to increases in attention, behavior and self-regulation problems over time for adolescents already at risk for mental health issues, a new study from Duke University finds.
Hold-up in ventures for technology transfer
The transfer of technology brings ideas closer to commercialization. The transformation happens in several steps, such as invention, innovation, building prototypes, production, market introduction, market expansion, after sales services.
The ultimate green technology
Imagine patterning and visualizing silicon at the atomic level, something which, if done successfully, will revolutionize the quantum and classical computing industry.
New technology detects COPD in minutes
Pioneering research by Professor Paul Lewis of Swansea University's Medical School into one of the most common lung diseases in the UK, Chronic Obstructive Pulmonary Disease, has led to the development of a new technology that can quickly and easily diagnose and monitor the condition.
New technology for powder metallurgy
Tecnalia leads EFFIPRO (Energy EFFIcient PROcess of Engineering Materials) project, which shows a new manufacturing process using powder metallurgy.
New milestone in printed photovoltaic technology
A team of researchers at Friedrich-Alexander-Universität have achieved an important milestone in the quest to develop efficient solar technology as an alternative to fossil fuels.
Gene Drive Technology: Where is the future?
For this episode of BioScience Talks, we're joined by Gene Drive Committee co-chair James P.
Could Hollywood technology help your health?
The same technology used by the entertainment industry to animate characters such as Gollum in 'The Lord of The Rings' films, will be used to help train elite athletes, for medical diagnosis and even to help improve prosthetic limb development, in a new research center at the University of Bath launched today.
Assessing carbon capture technology
Carbon capture and storage could be used to mitigate greenhouse gas emissions and thus ameliorate their impact on climate change.
New technology for dynamic projection mapping
It has been thought technically difficult to achieve projection mapping onto a moving/rotating object so that images look as though they are fixed to the object.

Best Science Podcasts 2017

We have hand picked the best science podcasts for 2017. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: Radiolab

Radiolab Presents: Anna in Somalia
This week, we are presenting a story from NPR foreign correspondent Gregory Warner and his new globe-trotting podcast Rough Translation. Mohammed was having the best six months of his life - working a job he loved, making mixtapes for his sweetheart - when the communist Somali regime perp-walked him out of his own home, and sentenced him to a lifetime of solitary confinement.  With only concrete walls and cockroaches to keep him company, Mohammed felt miserable, alone, despondent.  But then one day, eight months into his sentence, he heard a whisper, a whisper that would open up a portal to - of all places and times - 19th century Russia, and that would teach him how to live and love again. 
Now Playing: TED Radio Hour

Future Consequences
From data collection to gene editing to AI, what we once considered science fiction is now becoming reality. This hour, TED speakers explore the future consequences of our present actions. Guests include designer Anab Jain, futurist Juan Enriquez, biologist Paul Knoepfler, and neuroscientist and philosopher Sam Harris.