The strength of titanium, density of water: engineers have created a “metal wood”

High-performance Golf clubs and aircraft wings are made of titanium, which is stronger than steel and twice as light. These properties depend on the method of stacking the metal atoms, but occasional defects in the production process, mean that these materials can be much stronger, but will not. The architect, collecting metals from individual atoms, could design and build new materials that will have the best ratio between strength and weight.

The tree of metal — possible?

In the new study, published in Nature Scientific Reports, researchers from the School of engineering and applied science University of Pennsylvania, the University of Illinois and the University of Cambridge, has done just that. They gathered sheet of Nickel with nano-sized pores that make it as strong as titanium, but four to five times easier.

The empty space of the pores and the process of doing self-Assembly of porous metal similar to a natural material such as wood.

And exactly the same as the porosity of the tree trunk performs the biological function of transporting energy, empty space in the “metal wood” can be filled with other materials. Forests filling the anode and the cathode materials will allow a metal wood to serve a dual purpose: to be an airplane wing or a leg with battery.

The study was managed by James Pikul, associate Professor, Department of mechanical engineering and applied mechanics at the University of Pennsylvania.

Even the best elemental metals have defects in the arrangement of atoms, which limit their strength. A block of titanium, where every atom would be perfectly aligned with their neighbors, were ten times stronger than what you can produce now. The materials scientists have tried to use this phenomenon, using an architectural approach, designing structures with geometric control you need to unlock the mechanical properties that occur in nano-sized scale, where the defects have a reduced impact.

Pikul and his colleagues owe their success to nature.

“The reason we call this metal tree is not only its density, which is equal to the density of the wood, but also in cell nature,” says Pikul. “Cellular materials are porous; if you look at wood grain (a typical picture of the wood laminate) what you will see? More thick and dense part of the holding structure, and more porous parts are necessary to maintain biological functions, like transport into the cell and out of her.”

“Our structure is similar,” he says. “We have areas that are thick and dense, with sturdy metal struts and areas that are porous, with air gaps. We just work at the scale lengths where the strength of the struts is approaching the theoretical maximum”.

Spacers metal wood have a width of about 10 nanometers, or 100 atoms of Nickel in diameter. Other approaches include the use of technologies like three-dimensional printing, creating nano-scale forests of up to 100 nanometers, but a slow and painstaking process difficult to scale to useful sizes.

“We knew that reducing the size will make you stronger for a while, but people are unable to make these durable materials are large enough structures to be able to do something useful. Most examples are made of durable materials, was the size of a small flea, but with our approach we can make samples of metal of wood, which is 400 times more.”

The method of Pikul starts with tiny plastic spheres with a diameter of several hundred nanometers, suspended in water. When the water slowly evaporates, the spheres are deposited and are formed as a Cannonball, forming an ordered, crystalline frame. Using electroplating, which commonly add a thin layer of chrome to the dome, the scientists then filled with plastic spheres with Nickel. Once the Nickel is in place, the plastic spheres are dissolved, leaving an open network of metallic struts.

“We made a foil of the metal tree the size of a square centimeter — face of the dice,” says Pikul. “To give you an idea of scale, I would say that in a piece this size is about 1 billion Nickel spacers”.

Because the resulting material consists of 70% of empty space, the density of wood metal based on Nickel is extremely low relative to its strength. At a density equal to the density of water, the bricks of such material will float.

The following task teams will be playing this production process on a commercial scale. Unlike the Titan, none of the involved materials is not particularly rare or expensive by itself, but the infrastructure needed to operate at the nanoscale, are currently limited. Once it is developed, economies of scale will make the production of a significant quantity of wood is faster and cheaper.

As soon as researchers will be able to produce samples of their metal wood in large sizes, they will be able to expose them to more extensive tests. For example, it is very important to better understand their properties under tension.

“We don’t know for example whether our metal tree bend like metal or shatter like glass. Just as random defects in titanium limit its overall strength, we need to better understand how defects in the metal struts of wood affect its General properties.”

What applications might appear in this iron wood? Invite to our channel in the Telegram.

Leave a Reply

Your email address will not be published. Required fields are marked *