As an element, titanium has become the lifeblood of many engineering endeavors thanks to its immense strength and significantly less weight than steel. It is the reason why it has been widely used in the aerospace and marine industry, as well as in the storage of nuclear waste.
However, a team of scientists from the University of Pennsylvania, the University of Illinois and the University of Cambridge set out to improve the natural element by building something completely new at the atomic level : the result is a nickel sheet built at the nanoscale, composed of pores that resemble wood – hence the name “metallic wood” -; it is as strong as titanium, but up to five times lighter . The results of the work have been published in the journal Nature Scientific Reports.
Metallic wood?
Explaining the concept further, the researchers said that just as the porosity of the wood grains fulfills the biological function of transporting energy, the empty space in the created metallic wood can be infused with other materials. By making it with anode and cathode materials, the resulting material could serve a dual purpose, like a prosthetic leg that is also a battery.
Pushing the theoretical maximum
“The reason we call it metallic wood is not just because of its density, which has to do with wood, but because of its cellular nature, ” said James Pikul of the University of Pennsylvania. “We have areas that are thick and dense with strong metal struts, and areas that are porous with air gaps,” explains James Pikul, study director and professor in the Department of Mechanical Engineering and Applied Mechanics at Penn Engineering . “
These struts are only 10 nanometers wide , equivalent to 100 nickel atoms, and are substantially larger than any of the above.
“We know that being smaller makes you stronger for some time, but they hadn’t been able to make these structures out of strong materials that were big enough to be of use,” Pikul said. “Most of the examples made with strong materials have been the size of a small flea, but with our approach we can make metallic wood samples that are 400 times larger .”
Applications
Thus, the quality of “metallic wood” resides in the fact that large structures could be built with it, which cannot be conceived with a 3D printer or other strong but small materials.
Because approximately 70% of the resulting material is void, the density of this nickel-based metal wood is extremely low relative to its strength. With a density on par with water, a brick of this material would float on water.
The next big challenge for researchers is finding a way to produce it on a commercial scale , as the infrastructure to make it is currently limited. Once they have mastered this, they can build it on much larger scales for testing, such as to see if it breaks like glass.
Referencia: James H. Pikul et al, High strength metallic wood from nanostructured nickel inverse opal materials, Scientific Reports (2019). DOI: 10.1038/s41598-018-36901-3
Crédito imagen:University of Pennsylvania
