Tag Archives: metals

Nanotwinned copper materials with nanovoids are damage-tolerant with regard to radiation

The research comes out of the Texas A&M University, from a May 29, 2015 news item on Azonano,

Material performance in extreme radiation environments is central to the design of future nuclear reactors. Radiation in metallic materials typically induces significant damage in the form of dislocation loops and continuous void growth, manifested as void swelling. In certain metallic materials with low-to-intermediate stacking fault energy, such as Cu [copper] and austenitic stainless steels, void swelling can be significant and lead to substantial degradation of mechanical properties.

By using in situ heavy ion irradiation in a transmission electron microscope (in collaboration with M.A. Kirk at IVEM facility at Argonne National Lab), Zhang’s [Xinghang Zhang] student, Dr. Youxing Chen, reported a surprising phenomena: during radiation of nanotwinned Cu, preexisting nanovoids disappeared.

A May 28, 2015 Texas A & M University news release, which originated the news item, expands on the theme,

The self-healing capability of Cu arises from the existence of three-dimensional coherent and incoherent twin boundary networks. Such a network enables capture and rapid transportation of radiation induced point defects and their clusters to nanovoids (as evidenced by in situ radiation experiments and molecular dynamics simulations performed in collaboration with Jian Wang at Los Alamos National Laboratory), and thus lead to the mutual elimination of defect clusters and nanovoids.

This study also introduces the concept that deliberate introduction of nanovoids in conjunction with nanotwins may enable unprecedented radiation tolerance in metallic materials. [emphasis mine] The mobile twin boundaries are swift carriers that load and transfer “customers” (defect clusters), and nanovoids are also necessary to accommodate these “customers.” The in situ radiation study also shows that after annihilation of nanovoids, the self-healing capability of nanotwinned Cu is degraded, highlighting the significance of nanovoids. The concept developed from this study, the combination of nanovoids with nanotwin networks, may also stimulate the design of damage tolerant materials in general that are subjected other extreme environments, such as high stress and high pressure impact.

Here’s a link to and a citation for the paper,

Damage-tolerant nanotwinned metals with nanovoids under radiation environments by Y. Chen, K Y. Yu, Y. Liu, S. Shao, H. Wang, M. A. Kirk, J. Wang, & X. Zhang. Nature Communications 6, Article number: 7036 doi:10.1038/ncomms8036 Published 24 April 2015

This paper is open access.

Gold atoms: sometimes they’re a metal and sometimes they’re a molecule

Fascinating work out of Finland shows that a minor change in the number of gold atoms in your gold nanoparticle can mean the difference between a metal and a molecule (coincidentally, this phenomenon is alluded to in my April 14, 2015 post (Nature’s patterns reflected in gold nanoparticles); more about that at the end of this piece. Getting back to Finland and when gold is metal and when it’s a molecule, here’s more from an April 10, 2015 news item on ScienceDaily,

Researchers at the Nanoscience Center at the University of Jyväskylä, Finland, have shown that dramatic changes in the electronic properties of nanometre-sized chunks of gold occur in well-defined size range. Small gold nanoclusters could be used, for instance, in short-term storage of energy or electric charge in the field of molecular electronics. Funded by the Academy of Finland, the researchers have been able to obtain new information which is important, among other things, in developing bioimaging and sensing based on metal-like clusters.

An April 10, 2015 news release (also on EurekAlert) on the Academy of Finland (Suomen Akatemia) website, which originated the news item, describes the work in more detail,

Two recent papers by the researchers at Jyväskylä (1, 2) demonstrate that the electronic properties of two different but still quite similar gold nanoclusters can be drastically different. The clusters were synthesised by chemical methods incorporating a stabilising ligand layer on their surface. The researchers found that the smaller cluster, with up to 102 gold atoms, behaves like a giant molecule while the larger one, with at least 144 gold atoms, already behaves, in principle, like a macroscopic chunk of metal, but in nanosize.

The fundamentally different behaviour of these two differently sized gold nanoclusters was demonstrated by shining a laser light onto solution samples containing the clusters and by monitoring how energy dissipates from the clusters into the surrounding solvent.

“Molecules behave drastically different from metals,” said Professor Mika Pettersson, the principal investigator of the team conducting the experiments. “The additional energy from light, absorbed by the metal-like clusters, transfers to the environment extremely rapidly, in about one hundred billionth of a second, while a molecule-like cluster is excited to a higher energy state and dissipates the energy into the environment with a rate that is at least 100 times slower. This is exactly what we saw: the 102-gold atom cluster is a giant molecule showing even a transient magnetic state while the 144-gold atom cluster is already a metal. We’ve thus managed to bracket an important size region where this fundamentally interesting change in the behaviour takes place.”

“These experimental results go together very well with what our team has seen from computational simulations on these systems,” said Professor Hannu Häkkinen, a co-author of the studies and the scientific director of the nanoscience centre. “My team predicted this kind of behaviour back in 2008-2009 when we saw big differences in the electronic structure of exactly these nanoclusters. It’s wonderful that robust spectroscopic experiments have now proved these phenomena. In fact, the metal-like 144-atom cluster is even more interesting, since we just published a theoretical paper where we saw a big enhancement of the metallic properties of just a few copper atoms mixed with gold.” (3)

Here are links to and citation for the papers,

Ultrafast Electronic Relaxation and Vibrational Cooling Dynamics of Au144(SC2H4Ph)60 Nanocluster Probed by Transient Mid-IR Spectroscopy by Satu Mustalahti, Pasi Myllyperkiö, Tanja Lahtinen, Kirsi Salorinne, Sami Malola, Jaakko Koivisto, Hannu Häkkinen, and Mika Pettersson. J. Phys. Chem. C, 2014, 118 (31), pp 18233–18239 DOI: 10.1021/jp505464z Publication Date (Web): July 3, 2014

Copyright © 2014 American Chemical Society

Copper Induces a Core Plasmon in Intermetallic Au(144,145)–xCux(SR)60 Nanoclusters by Sami Malola, Michael J. Hartmann, and Hannu Häkkinen. J. Phys. Chem. Lett., 2015, 6 (3), pp 515–520 DOI: 10.1021/jz502637b Publication Date (Web): January 22, 2015

Copyright © 2015 American Chemical Society

Molecule-like Photodynamics of Au102(pMBA)44 Nanocluster by Satu Mustalahti, Pasi Myllyperkiö, Sami Malola, Tanja Lahtinen, Kirsi Salorinne, Jaakko Koivisto, Hannu Häkkinen, and Mika Pettersson. ACS Nano, 2015, 9 (3), pp 2328–2335 DOI: 10.1021/nn506711a Publication Date (Web): February 22, 2015

Copyright © 2015 American Chemical Society

These papers are behind paywalls.

As for my April 14, 2015 post (Nature’s patterns reflected in gold nanoparticles), researchers at Carnegie Mellon University were researching patterns in different sized gold nanoparticles when this was noted in passing,

… Normally, gold is one of the best conductors of electrical current, but the size of Au133 is so small that the particle hasn’t yet become metallic. …

Improving firearm performance with Duralar, a diamond-based coating

A metal and diamond-based coating, Duralar,used to give metal better hardness and durability is also good for guns. I checked a few times and the April 1, 2015 news item on Azonano does not appear to be an April Fool’s joke,

ProtoTactical, a Tucson-area manufacturer of firearms and firearm components has discovered a new way to significantly improve their firearm performance — by applying a special nanotechnology coating called Duralar™. Duralar is an advanced, diamond-based coating that is being used in a variety of industries to enhance metal hardness and durability — and to provide other qualities as well.

Confirming the unlikelihood of this news being a joke is a March 31, 2015 Duralar Coatings news release about the coating and guns,

“Our use of Duralar coatings began as an experiment,” said Gary Palese, president of ProTactical. “I coated a few standard AR-15 trigger parts, mainly to check out the increased durability and wear resistance. But I got a nice surprise and an interesting bonus…”

“As soon as we installed a Duralar-coated trigger and dry-fired the weapon we immediately discovered that the trigger action was significantly smoother. Customers who tried it were amazed at the difference between the coated and uncoated triggers. They were certain that we must have changed the springs or reground the edges, or something! But the only difference was Duralar.”

“Because Duralar is a carbon-based material it has a natural, dry lubricity,” explained Andrew Tudhope, president of Duralar North America. “In firearm applications this means smoother action, less friction and no need for liquid lubricants, which can collect dirt and cause jamming. So, when you combine the intrinsic lubricity with Duralar’s hardness and increased wear and scratch resistance, it gives gun manufacturers a very useful suite of performance features.”

Sex appeal

Gary Palese is also pleased with another Duralar feature, which he calls “sex appeal!”  “Duralar coating gives metals a unique pearlescent gray-black surface that is very tactical and ‘stealthy’ looking — which many of our customers find very sexy! So, because of its hardness and attractive appearance, I’m going to start using Duralar to coat our line of custom knife blades, as well.”

Introduced by Duralar Technologies in 2012, Duralar is an advanced, uniquely structured nanocomposite coating that blends metal and diamond-based components to achieve exceptional hardness, toughness, strength and a spectrum of performance qualities. It is comprised of multiple layers that can be configured in multiple ways to address different applications. Because of its many features Duralar is finding use in an ever-widening range of metal-coating applications. In addition to hardness, durability and lubricity the coatings also provide excellent corrosion and erosion resistance, and they are environmentally friendly, as well.

About Duralar Technologies

Duralar Technologies is a global nanotechnology company and developer of the state-of-the-art Duralar family of ultra-hard coatings. The diamond-based next-generation products are designed to replace hard chrome plating, thermal spray and other previous generations of hard coatings in a broad range of industries including oil & gas, automotive, pulp & paper and aerospace. The company sells and supports Duralar’s coating technology as well as the systems, precursors and materials used in the Duralar coating process. In addition, Duralar Technologies provides Duralar coating services for selected customers. The company’s U.S. headquarters are located in Marana, AZ. European headquarters are in Bedizzole, Italy. The company has additional facilities and offices in Brazil, Mexico and the U.S. For more information, visit www.duralar.com.

About ProtoTactical

ProtoTactical LLC, based in Marana, AZ, is a precision machine shop and manufacturer of AR-style firearms and accessories under its own name as well as for other firearms companies across the U.S. and around the world. The company specializes in reliability at an affordable price, delivering unique product solutions as well as tried-and-true designs. With its rapid prototyping, design and manufacturing capabilities ProtoTactical is able to supply virtually any firearm or component in-house and respond quickly to customer needs. ProtoTactical is a division of ProtoTech, a full-service product development and high-precision machine shop. Established in 1995, ProtoTech is a respected member of Tucson’s advanced technology industry, supplying quality precision parts worldwide. For more information, visit www.prototactical.com.

I found this about the coating technology on Duralar Coatings’ Advanced Technology webpage (Note: Links have been removed),

Duralar is a proprietary and uniquely structured new nanocomposite coating that blends metal and diamond-based components to achieve exceptional hardness, toughness, strength and a broad range of performance qualities. It is comprised of multiple layers that can be configured in different ways to address different applications. The multiple layers are also effective for eliminating microcracks in the coating and blocking other problems like corrosion.

Because Duralar is not a sprayed coating it does not have the limitations that are usually associated with line-of-sight application. Instead, Duralar is highly conformal and uniform, which makes it well suited to coating three-dimensional features. It gives very consistent coverage, even on screw threads and intricately shaped features which can be challenging for other coating methods.

Also, Duralar does not require extremely high deposition temperatures, so it does not alter the morphology of substrates and works well on a broad range of substrate materials. At present Duralar technology is primarily designed to coat conductive substrates; in the future it may also be used on plastics and other materials.

Duralar offers this image of diamonds to illustrate their point,

Duralar is a nanocomposite blend of metal and diamond components.

Duralar is a nanocomposite blend of metal and diamond components.

Hydrogen ‘traffic jams’ and embrittlement

Here’s something about how hydrogen atoms cause metals to become embrittled, from  a Nov. 19, 2012 McGill University (Montréal, Québec) news release,

Hydrogen, the lightest element, can easily dissolve and migrate within metals to make these otherwise ductile materials brittle and substantially more prone to failures.

Since the phenomenon was discovered in 1875, hydrogen embrittlement has been a persistent problem for the design of structural materials in various industries, from battleships to aircraft and nuclear reactors. Despite decades of research, experts have yet to fully understand the physics underlying the problem or to develop a rigorous model for predicting when, where and how hydrogen embrittlement will occur.  As a result, industrial designers must still resort to a trial- and-error approach.

Now, Jun Song, an Assistant Professor in Materials Engineering at McGill University, and Prof. William Curtin, Director of the Institute of Mechanical Engineering at Ecole Polytechnique Federale de Lausanne in Switzerland, have shown that the answer to hydrogen embrittlement may be rooted in how hydrogen modifies material behaviours at the nanoscale.  In their study, published in Nature Materials, Song and Curtin present a new model that can accurately predict the occurrence of hydrogen embrittlement.

Under normal conditions, metals can undergo substantial plastic deformation when subjected to forces. This plasticity stems from the ability of nano-  and micro-sized cracks to generate “dislocations” within the metal – movements of atoms that serve to relieve stress in the material.

“Dislocations can be viewed as vehicles to carry plastic deformation, while the nano- and micro-sized cracks can be viewed as hubs to dispatch those vehicles,” Song explains. “The desirable properties of metals, such as ductility and toughness, rely on the hubs functioning well.  Unfortunately those hubs also attract hydrogen atoms. The way hydrogen atoms embrittle metals is by causing a kind of traffic jam: they crowd around the hub and block all possible routes for vehicle dispatch. This eventually leads to the material breaking down.”

State-of-the-art computer simulations were performed by Song to reveal explicitly how hydrogen atoms move within metals and how they interact with metal atoms. This simulation was followed by rigorous kinetic analysis, to link the nanoscale details with macroscopic experimental conditions.

This model has been applied to predict embrittlement thresholds in a variety of ferritic iron-based steels and produced excellent agreements with experiments.  The findings provide a framework for interpreting experiments and designing next-generation embrittlement-resistant structural materials.

Here’s a citation for the paper and a link,

Atomic mechanism and prediction of hydrogen embrittlement in iron” by Jun Song & W. A. Curtin in Nature Materials (2012) doi:10.1038/nmat3479 (advance online publication Nov.11, 2012)

This article is behind a paywall.

New metals, inflatable, origami-style, and self-healing

I’m still having trouble imagining inflatable metal objects but according to Ariel Schwartz’s article in Fast Company, it does exist. There’s even a slide show about how to make an inflatable chair at the Fast Company website. (I decided to show the stool.)

Inflatable metal stool (from Fast Company slide show)

From the article,

Designed by architect Oskar Zieta and materials scientist Philipp Dohmen, the chair is built with thin sheet metal that has been inflated with tubes releasing high-pressure air. The pair have also built an inflatable metal stool. Zieta and Dohmen are also working on large-scale installations.

I wish there was more information about the technology but I’m reasonably certain this could be described as a nano-enabled product. It’s certainly an interesting product although I’m having difficulty understanding why someone would want an inflatable metal chair or stool but I’m pretty slow about these kinds of things. I see more more possibilities for the origami-based designs from Industrial Origami that will cut down on the amount of sheet metal needed for products such as ovens. As for the Fraunhofer Institute’s self-healing metal,  that seems like an excellent idea and is definitely nano-enabled technology.