Humans have made clever use of metals and ceramics for thousands of years. Carbons — coal, graphite, diamond etc. — have likewise found human use for thousands of years. But it is only recently that humans have begun to learn how to consciously manipulate these materials at the atomic, molecular, and fine crystalline layers to incorporate special properties into the ceramics, metals, and carbons.
“If you go very fast, about 10 times speed of sound within the atmosphere, then any vehicle will heat up tremendously because of air friction,” said Tobias Schaedler, senior scientist at HRL Laboratories in Malibu, Calif. “People want to build hypersonic vehicles and you need ceramics for the whole shell of the vehicle.”
Schaedler and colleagues at HRL invented a resin formulation that can be 3-D printed into parts of virtually any shape and size.
The printed resin can then be fired, converting it into a high strength, fully dense ceramic. The resulting material can withstand ultrahigh temperatures in excess of 1,700 degrees Celsius (3,092 Fahrenheit) and is 10 times stronger than similar materials.
More on the new HRL technique for 3D printed ceramics:
The promise of additive manufacturing or 3-D printing—faster and cheaper manufacturing of more customizable parts—is limited by the palette of printable materials, which until now has included mainly polymers and some metals. Now we can add ceramics, an important class of materials whose high strength and resistance to heat, chemical degradation, and friction make them attractive for use in the military and the aerospace industries for everything from exterior airplane parts to small components for rockets.
… The researchers at HRL Labs [developed] a new printable resin made of so-called preceramic polymers, which can be converted into ceramics by heating them at high temperatures. They demonstrated that the new resin is compatible with a popular additive manufacturing technique called stereolithography, in which a laser beam is used to build structures layer by layer from a liquid polymer. The researchers also showed that it works with a specialized technique that employs ultraviolet light and patterned masks to build complex 3-D structures like lattices, 100 to 1,000 times as rapidly as conventional stereolithography can. After printing, the researchers heated the parts to turn them into ceramics and demonstrated their impressive mechanical properties.
Ceramics Inside Metals
Ceramic particles have long been considered as a potential way to make metals stronger. However, with microscale ceramic particles, the infusion process results in a loss of plasticity.
Nanoscale particles, by contrast, can enhance strength while maintaining or even improving metals’ plasticity. But nanoscale ceramic particles tend to clump together rather than dispersing evenly, due to the tendency of small particles to attract one other.
To counteract this issue, researchers dispersed the particles into a molten magnesium zinc alloy. The newly discovered nanoparticle dispersion relies on the kinetic energy in the particles’ movement. This stabilizes the particles’ dispersion and prevents clumping.
To further enhance the new metal’s strength, the researchers used a technique called high-pressure torsion to compress it.
“The results we obtained so far are just scratching the surface of the hidden treasure for a new class of metals with revolutionary properties and functionalities,” Li said.
The new metal (more accurately called a metal nanocomposite) is about 14 percent silicon carbide nanoparticles and 86 percent magnesium. The researchers noted that magnesium is an abundant resource and that scaling up its use would not cause environmental damage.
High Entropy Alloys
High-entropy alloys are materials that consist of five or more metals in approximately equal amounts. These alloys are currently the focus of significant attention in materials science and engineering because they can have desirable properties.
The NC State research team combined lithium, magnesium, titanium, aluminum and scandium to make a nanocrystalline high-entropy alloy that has low density, but very high strength.
“The density is comparable to aluminum, but it is stronger than titanium alloys,” says Dr. Carl Koch, Kobe Steel Distinguished Professor of Materials Science and Engineering at NC State and senior author of a paper on the work. “It has a combination of high strength and low density that is, as far as we can tell, unmatched by any other metallic material. The strength-to-weight ratio is comparable to some ceramics, but we think it’s tougher – less brittle – than ceramics.” __ https://news.ncsu.edu/2014/12/koch-high-entropy-alloy-2014/
Steel – Aluminum Alloy Substitute for Titanium
Today a team of material scientists at Pohang University of Science and Technology in South Korea announced what they’re calling one of the biggest steel breakthroughs of the last few decades: an altogether new type of flexible, ultra-strong, lightweight steel. This new metal has a strength-to-weight ratio that matches even our best titanium alloys, but at one tenth the cost, and can be created on a small scale with machinery already used to make automotive-grade steel. The study appears in Nature.
New way of forming titanium for better combinations of strength and ductility:
The researchers began by using asymmetric rolling to process a two-millimeter thick sheet of titanium. In asymmetric rolling, the sheet passes between two rollers that apply pressure to each side of the sheet, but one of the rollers rotates more quickly than the other. This not only presses the sheet thinner but, because of the different roller speeds, also creates a sheer strain in the metal.
In other words, the crystal structure within the titanium moves forward faster on the side of the fast roller than on the side of the slow roller. This effectively distorts and breaks down the crystalline structure, creating small grains in the material.
The researchers repeated the asymmetric rolling process until the metal was 0.3 millimeters thick, then exposed the sheet to 475 degrees Celsius for five minutes. This allowed some – but not all – of the small grains to consume each other and form large grains.
This second process creates a patchwork quilt of small and large grains. The large grains are laid out in long, narrow columns, with each column completely surrounded by a layer of small grains.
The resulting material is as strong as the small-grained titanium because the surrounding layer of small grains makes it difficult for the large grains to deform.
What happens when you mix the physical properties of glass (brittle and flowing) and metal (stiff and tough)? You get metal glass, of course. Since the 1960s, scientists showed you can make certain alloys into metal glass by rapidly cooling them. Really, really fast. Hundreds of degrees in a fraction of a second. Eventually you end up with an alloy that both behaves like a metal and glass. Some are three times stronger than titanium and have the elastic modulus of bone, all while being extremely lightweight. They’re also a lot more easy to machine than metals. All in all, metal glass is amazing and has the possibility to transform the world, just like another wonder material: graphene. So, why aren’t we seeing more of it? Part of the problem is that research is moving painfully slow, but this may set to change after a team of researchers in Sydney reported a model for the atomic structure of metal glass. If until now scientists were testing various alloys and technique in the dark, by trial and error, now they have a cook book for metal glass. __ Source
Metal, Ceramic, and Carbon Foams
Easily machinable to near-net-shape
Stable at high temperatures
Resistant to thermal shock
Ceramic and Metal Foams
High specific stiffness
High surface area
Low pressure drop
Tailorable pore size and foam density
Ability to apply solid ceramic or metal facesheets to create actively cooled structures
Fabrication from various ceramics and metals
Nano-carbon, ceramics, and metals can be combined in many ways to create materials that are stronger and more durable than any of the materials alone.
The introduction of nano-materials — very small particles and materials that have been formed through the fine manipulation of molecules and crystals — introduces a new dimension into the process of creating new structural and other futuristic materials.
“The excitement in nanotechnology is due to the unusual properties of materials when sizes of particles reduce to nanometres. This happens because of ‘electronic confinement’ — an effect when electron motion is limited to extremely short distances, of the order of nanometres,” he said.
This kind of reactions would mean that metallurgical processes may be done differently tomorrow. “Many nanoscale materials have new properties which are useful in catalysis. They could be luminescent or magnetic. Designer alloys with new properties may be made by these reactions,” he added. __ http://www.thehindu.com/sci-tech/science/iitm-designer-alloys-by-chemical-reactions/article8058592.ece
New Methods and Materials Applied to Old Processes
Modumetal uses an advanced form of electroplating, a process already used to make the chrome plating you might see on the engine and exhaust pipes of a motorcycle. Electroplating involves immersing a metal part in a chemical bath containing various metal ions, and then applying an electrical current to cause those ions to form a metal coating.
The company uses a bath that contains more than one kind of metal ion and controls how ions are deposited by varying the electrical current. By changing the current at precise moments, it can create a layered structure, with each layer being several nanometers thick and of different composition. The final coating can be up to a centimeter thick and can greatly change the properties of the original material.
The custom-creation of materials to suit particular functions is becoming a significant sector of human enterprise. Although the “material level” is but the ground-level of technology, it is beginning to incorporate most of the higher levels of technology — in addition to higher levels of science and cognition.
Today we have focused on structural materials made of metals, ceramic, and carbons. Impressive advances are being made here, but in terms of “materials,” these have barely scratched the surface of the possibilities.
These and other materials can be manipulated to form more advanced — even disruptive — catalysts, electronic components, coatings, thermal manipulation and protection, anti-projectile protection and clothing, cancer-killing materials, and a wide range of other material applications.
Progress in the “invisible disciplines” such as these, allows for much more salient progress in the visible world.
Unintelligent and undiscerning individuals are impressed by the flashy and the eye-catching items — advertisers, con-men, and propagandists are counting on the basic stupidity of the majority of the human race. Stupidity is without limit.
And still — mostly within the opportunity societies of the Anglosphere, parts of Europe, and parts of East Asia — disruptive innovations are taking place beneath the radar. The most disruptive of these innovations is the making of newer and more powerful tools that can then be used in science, technology, and everyday life to fire the cycle of human creation once again.
It is this invisible creativity that makes it possible for Julian Simon to make successful bets against Malthusian doom.
Drunken old men with nothing useful to do with themselves, tend to cluster on doomer websites — assuring each other in a circular jerkular echo choir that their ideas of doom are accurate and have always been accurate. They cannot see the real world for all the flatulent smoke they emit within their enclosed, limiting spaces.
Others who can think, plan, prevent and preempt problems, and actually solve problems — these people do not have time for the toothless talk of hapless doomers.
And yet we are all likely to die eventually, so doom is apt to fall on us, everyone. In such a case, what we do and what we leave behind — even if unappreciated and unacknowledged — is the measure of who we were.
Hope for the best. Prepare for the worst. It is never too late to have a Dangerous Childhood.