A new material that mimics coral could help remove toxic heavy metals like mercury from the ocean, according to a new study published in the Journal of Colloid and Interface Science. The researchers, from Anhui Jianzhu University in China, say their new material could provide inspiration for other approaches to removing pollutants.
Dr. Xianbiao Wang and colleagues have made coral-like nanoplates using aluminium oxide, with the aim of adsorbing mercury from water. Aluminium oxide has previously been used to remove pollutants, but the structure of the material has not been optimal, so they have not performed very well. The new nanoplates curl themselves up into a coral-like structure, which behaves in a similar way to real coral, making the material more effective.
More information:Journal of Colloid and Interface ScienceVolume 453, 1 September 2015, Pages 244–251. DOI: 10.1016/j.jcis.2015.03.065
Graphical abstract of synthetic coral. Credit: Elsevier
When a fragile surface requires a rock-hard, super-thin bonded metal coating, conventional manufacturing processes come up short. However, Cold Gas Dynamic Spray (CGDS) can do just that - with a big caveat. CGDS is enormously versatile, but is also very difficult to predict key aspects of the entire process. Now a temperature-based 3D model by Professor Tien-Chien Jen from the University of Johannesburg starts unlocking the mysteries of the CGDS film-growing process in the particle deposition zone.
Themodel is the first to connect the dots between particle impact velocity, energy transformation, and temperature rise in the particle impact zone, in three dimensions.
CGDS is already used extensively to manufacture or repair metal parts for large passenger airliners, as well as mobile technology and military equipment.
In the process, a de Laval nozzle sprays micron-sized metal particles over a short distance, typically 25mm, at a metal or polymer surface. The particles impact the surface at speeds ranging from 300 meters per second to 800 meters per second. As a frame of reference, the speed of sound is 343 meters per second.
A fundamental discovery that alters our current understanding of how metals solidify and form crystalline patterns may help lead to better control of casting and welding processes. It also explains how snowflakes and many mineral patterns form naturally.
Reexamining data from his 20-year-old NASA experiment involving the repeated freezing and melting of high-purity materials in microgravity, Martin Glicksman, research professor in materials science and the Allen Henry Chair at Florida Institute of Technology, working with Kumar Ankit at the School of Matter, Transport and Energy at Arizona State University, discovered the way nature guides formation of complex patterns in materials that crystallize.
Glicksman discovered an energy field affecting all crystallizing substances, which he labeled the bias field that he believes is nature’s way of guiding cellular and branching dendritic microstructures that form during solidification of most metals and alloys.
“In the last phases of melting, needle-like crystals suddenly changed to spheres, and so for the first time ever, as we watched stationary particles melting in microgravity and observed their rather remarkable shape change,” Glicksman said.
Tensile Strength is a determinable by yield strength, ultimate tensile strength elongation, and reduction in area. Tests measure the point at which can withstand being stretched before structural failure occurs. The values can differ greatly from the compressive strength of the material (which measures ability to withstand pressure)
The Periodic Table may not sound like a list of ingredients but, for a group of materials scientists, it’s the starting point for designing the perfect chemical make-up of tomorrow’s jet engines.
Inside a jet engine is one of the most extreme environments known to engineering.
In less than a second, a ton of air is sucked into the engine, squeezed to a fraction of its normal volume and then passed across hundreds of blades rotating at speeds of up to 10,000 rpm; reaching the combustor, the air is mixed with kerosene and ignited; the resulting gases are about a third as hot as the sun’s surface and hurtle at speeds of almost 1,500 km per hour towards a wall of turbines, where each blade generates power equivalent to the thrust of a Formula One racing car.
Yet another week begins, which means it’s time for METAL MONDAY! (Insert guitar solo here.) Today a profile a soft, silvery metal that looks a lot like mercury: gallium (Ga):
Gallium destroys the structure of aluminum-zinc alloys or steel, by diffusing in between their crystalline boundaries. That’s science speak for “don’t take this on a place, it will eat through the fuselage.”
The metal melts at about 302 K (29.7646 °C, 85.5763 °F) and boils more than eight times higher at 2673 K. According to Wikipedia (please fact check this for me!), this apparently gives gallium the greatest ratio between melting point and boiling point of any element.
French chemist Paul-Émile Lecoq de Boisbaudran discovered the element in 1875. It’s said he named the element “gallia” from the Latin Gallia, meaning Gaul.
Gallium is used in many alloys and also has useful applications in semiconductors.
Despite their ubiquity in consumer electronics, rare-earth metals are, as their name suggests, hard to come by. Mining and purifying them is an expensive, labor-intensive and ecologically devastating process. Starting with the two elements as a mixed powder, a metal-binding molecule known as a…
‘There are relatively few metals and alloys that are both ductile and strong enough at room temperature to withstand the cold drawn into wire. Platinum, silver, iron, aluminium, gold, copper, and alloys such as brass and bronze all have suitable properties.’
1. The earliest known example of metal being formed into wire comes from ancient Egypt almost 5,000 years ago.
2. The current method of wire drawing involves pulling ductile metal through a small hole in a die at room temperature.
3. Traditionally, wires used for electrical applications are usually coated in insulating polymers such as polyethylene or PVC.
4. Wires comprise a number of smaller strands, the smallest number being seven – one in the centre with six surrounding it. Some flexible wires can contain up to 100 individual strands.
5. Wires used in nanotechnology are 1D materials, made from metallic (Ni, Pt, Au), semiconducting (Si, InP, GaN) or insulating (SiO2, TiO2) materials.
For more on the history of wire, read Anna Ploszaski’s Material of the Monthpiecehere
A Cornell University lab is applying nanotechnology to make textiles do a whole range of new and useful tricks.
Chemical and biomolecular engineer Juan Hinestroza and his team in the textiles nanotechnology lab are adding tiny bits of metal into fibrous material like cotton. When woven into a textile, the augmented yarn can produce light, kill disease-causing microbes or act as a filter to trap harmful gas. In addition, the metal oxides allow the yarn to be fashioned into conductive components like transistors for electronics.
“We want to transform traditional natural fibers into true engineering materials that are multifunctional and that can be customized to any demand,” Hinestroza said. “We are chemists, we are material scientists, we are designers, we want to create materials that will perform many functions, yet remain as flexible and as comfortable as a t-shirt or an old pair of jeans.”
A salt used to create a green rocket fuel is known to decompose metals—such as those in metal propellant storage tanks. Recent research at the University of Illinois Urbana-Champaign found that there are also trace metals in the fuel itself and investigated a way to slow the decomposition using compounds that bind to metals.
“We knew from previous studies that metals work as a catalyst for decomposition in hydroxylammonium nitrate—a flight-proven monopropellant that you don’t have to wear a HAZMAT suit around—but we didn’t know the rate it decomposes, particularly when it’s exposed to heat,” said Emil Broemmelsiek, a Ph.D. student in the Department of Aerospace Engineering at UIUC. “The study I did focused on atmospheric pressure, so more like storage conditions. Over time, HAN in storage can dissolve the steel tank, which contains enough iron to catalyze the decomposition process.
"In the HAN samples from the manufacturer, we found trace amounts of metals—about a part-per-million level—but even those trace impurities have a catalytic effect. In this study, I checked the temperature at which it decomposes and how fast it decomposes. Then I used additives to see if they could be used to remove the metals. And it worked.”
A team of Northwestern University engineers has created a new way to print three-dimensional metallic objects using rust and metal powders.
While current methods rely on vast metal powder beds and expensive lasers or electron beams, Northwestern’s new technique uses liquid inks and common furnaces, resulting in a cheaper, faster, and more uniform process. The Northwestern team also demonstrated that the new method works for an extensive variety of metals, metal mixtures, alloys, and metal oxides and compounds.
“This is exciting because most advanced manufacturing methods being used for metallic printing are limited as far as which metals and alloys can be printed and what types of architecture can be created,” said Ramille Shah, assistant professor of materials science and engineering at Northwestern’s McCormick School of Engineering and of surgery in the Feinberg School of Medicine, who led the study. “Our method greatly expands the architectures and metals we’re able to print, which really opens the door for a lot of different applications.”
Perhaps no startup was launched for a more intriguing reason than that of Northeastern’s Hanchen Huang. From the company website:
“MesoGlue was founded by Huang and two of his PhD students: They had a dream of a better way of sticking things together.”
Those “things” are everything from a computer’s central processing unit and a printed circuit board to the glass and metal filament in a light bulb. The “way” of attaching them is, astonishingly, a glue made out of metal that sets at room temperature and requires very little pressure to seal. “It’s like welding or soldering but without the heat,” says Huang, who is professor and chair in the Department of Mechanical and Industrial Engineering.
In a new paper, published in the January issue of Advanced Materials & Processes, Huang and colleagues, including Northeastern doctoral student Paul Elliott, describe their latest advances in the glue’s development. Our curiosity was piqued: Soldering with no heat? We asked Huang to elaborate.
On new developments in the composition of the metallic glue:
“Both ‘metal’ and 'glue’ are familiar terms to most people, but their combination is new and made possible by unique properties of metallic nanorods–infinitesimally small rods with metal cores that we have coated with the element indium on one side and galium on the other. These coated rods are arranged along a substrate like angled teeth on a comb: There is a bottom 'comb’ and a top 'comb.’ We then interlace the 'teeth.’ When indium and galium touch each other, they form a liquid. The metal core of the rods acts to turn that liquid into a solid. The resulting glue provides the strength and thermal/?electrical conductance of a metal bond. We recently received a new provisional patent for this development through Northeastern University.”
Sandia National Laboratories researchers have made the first measurements of thermoelectric behavior by a nanoporous metal-organic framework (MOF), a development that could lead to an entirely new class of materials for such applications as cooling computer chips and cameras and energy…
The study of metallurgy and materials require of the knowledge of microstructures. Here is a microstructure of a non-chemical-attacked metal (steel1010). We can see absolutely nothing but little dots. This remarks the importance of chemical attacks to unveil the microstructure of metals.
Energy-harvesting magnets that change their volume when placed in a magnetic field have been discovered by US researchers. The materials described by Harsh Deep Chopra of Temple University and Manfred Wuttig of the University of Maryland produce negligible waste heat in the process and could displace current technologies and lead to new ones, such as omnidirectional actuators for mechanical devices and microelectromechanical systems (MEMS). [Nature, 2015, 521, 340-343; DOI:10.1038/nature14459]
All magnets change their shape but not their volume, even auxetic magnets were previously characterized on the basis of volume conserving Joule magnetostriction. This fundamental principle of volume conservation has remained unchanged for 175 years, since the 1840s, when physicist James Prescott Joule found that iron-based magnetic materials would elongate and constrict anisotropically but not change their volume when placed in a magnetic field, so-called Joule magnetostriction.
The work of Chopra, Wuttig changes that observation fundamentally with the demonstration of volume-expanding magnetism. “Our findings fundamentally change the way we think about a certain type of magnetism that has been in place since 1841,” explains Chopra. “We have discovered a new class of magnets, which we call ‘Non-Joulian Magnets,’ that show a large volume change in magnetic fields.” Chopra described the phenomenon to us: “When ‘excited’ by a magnetic field, they swell up like a puffer fish,” he says.
Dangerous lead levels in drinking water in cities across the nation have recently made national headlines. Water contaminated with lead, mercury, or other heavy metals poses serious problems for not only our health but also for our environment.
At the Agricultural Research Service’s (ARS) National Center for Agricultural Utilization Research (NCAUR) in Peoria, Illinois, scientists are investigating safe ways to remove heavy metals from various substances. Recently, they developed and patented a new method that uses vegetable oils to remove metals from liquids, solids, and gases.
Rex Murray, research leader at NCAUR’s Bio-Oils Research Unit, and his colleagues have created a chemical process to modify vegetable oils into “functionalized” vegetable oils that effectively separate heavy metal ions fromwater. The team included chemist Kenneth Doll, physical scientist Grigor Bantchev, chemical engineer Robert Dunn, and physical science technician Kim Ascherl.
Antiferromagnets have generated significant interest for future computing technologies due to their fast dynamics, their ability to generate and detect spin-polarized electric currents, and their robustness against external magnetic fields. Despite these bright prospects, the vanishing total magnetization in antiferromagnets makes it difficult to evaluate their internal magnetic structure compared with their ferromagnetic counterparts.
Limited understanding of the internal magnetic structure of antiferromagnetic materials and devices is a major obstacle to manipulating and efficiently utilizing variations in their magnetic state. In work that sheds light on a new set of antiferromagnetic materials, an international research team led by researchers at the National Institute of Standards and Technology (NIST), the United States Naval Research Laboratory, the Johns Hopkins University, the Institute for Solid State Physics (ISSP), and the University of Tokyo have identified a metallic antiferromagnet (Mn3Sn) that exhibits a large spontaneous magneto-optic Kerr effect (MOKE), despite a vanishing total magnetization at room temperature. A metallic antiferromagnet with a large spontaneous MOKE promises to be a vital tool for future antiferromagnetic memory devices, where the device state could be read optically and switched either optically or with a spin-polarized electric current.
According to Dictionary.com, steel is “any of various modified forms of iron, artificially produced, having a carbon content less than that of pig iron and more than that of wrought iron, and having qualities of hardness, elasticity, and strength varying according to composition and heat treatment: generally categorized as having a high, medium, or low-carbon content”.
Perhaps the most well known alloy around, as well as one of the most common materials in the world, steel is essentially iron with a small percentage of carbon (and, on occasion, one or more other elements). Not enough carbon and you’re stuck with wrought iron, too much carbon and you get cast iron. The graph above is a binary iron-carbon phase diagram that goes from zero percent carbon to about 6.5 percent, illustrating the various phases that can form.
Steel has been known about since ancient times, some pieces dating back to 1800 BC, but it was the invention of the Bessemer process during the industrial revolution that really popularized the alloy. (Technically, similar methods had been used before, particularly in China and Japan, but Henry Bessemer invented the modern method, industrializing it and obtaining a patent in 1856.)
Mainly used in construction, the alloy has been used for almost every possible application: from office furniture to steel wool, from bulldozers to washing machines, and from wires to watches, the possibilities are pretty much endless. Steel is also one of the world’s most-recycled materials, able to be used more than once, with a recycling rate of over 60% globally.
The addition of carbon allows the steel to be stronger than the iron it’s made from. Adding nickel and manganese increases its tensile strength, chromium increases hardness and melting temperature, and vanadium also increases hardness while making it less prone to metal fatigue. Stainless steel has at least eleven percent chromium, whereas Hadfield steel (which resists wearing) contains twelve to fourteen percent manganese. Check out theselinks for more information on the effects of adding certain elements.
Forging blank (Titanium, grade 1): taken pictures with polarized light || on the left side: oxygenated edge area (needles visible) || on the right side: regular microstructure in the core area
