Industries like automobile, aeronautics mainly focus on the weight of the product without compromising the quality and also to increase the performance of their product. So this metallic wood is really helpful for them to build the important components of their product.
Scientists have created a "Metallic Wood" that has the strength of titanium and the density of water. In a paper published in Nature Scientific Reports, researchers from University of Pennsylvania School of Engineering and Applied Science, the University of Illinois at Urbana–Champaign, the University of Cambridge, and Middle East Technical University in Ankara, Turkey have built this metallic wood.
The performance of a material can be determined by using the strength-to-weight ratio. The metallic wood has a high strength-to-weight ratio. To attain a reduced weight as well as good strength, a material must have the proper alignment in grain structure. So the scientists concentrated more on the structure of metallic wood.
Generally, natural metals have defects in their atomic arrangement which is the main reason for the loss of strength in the metal. If every atom in metal is perfectly aligned with its neighbours, then the strength would be higher. That is how the structure in the titanium is aligned which ensures high strength. So, material researchers thought of implementing the phenomena as in titanium in their architectural approach to design a material where they mainly focus on geometry control that needs to maintain in the nanoscale level.
The scientists used to call it as a metallic wood. Because it has high mechanical strength and the chemical stability of metal, as well as density closer to wood.
“The reason we call it metallic wood is not just its density, which is about that of wood, but its cellular nature,” James Pikul says. “Cellular materials are porous; if you look at wood grain, that’s what you’re seeing parts that are thick and dense and made to hold the structure, and parts that are porous and made to support biological functions, like transport to and from cells.”
“Our structure is similar,” he says. “We have areas that are thick and dense with strong metal struts, and areas that are porous with air gaps. We’re just operating at the length scales where the strength of struts approaches the theoretical maximum.”
The geometric dimensions of metallic wood are around 10 nanometers wide, or about 100 nickel atoms across. The manufacturing method is 3D-printing-like techniques to make nanoscale scaffoldings with great precision about hundred-nanometer. The process of making into a useful size would be slower and also it involves various steps to create.
James Pikul’s manufacturing method is as follows, From tiny plastic spheres with few hundred nanometers in diameter are suspended in water. When the water is slowly started to evaporate, the spheres settle slowly and will stack like cannonballs that provides an orderly, crystalline framework. Then by using electroplating, the same technique that adds a thin layer of chrome to a hubcap, the researchers then infiltrate the plastic spheres along with nickel. Once the nickel is in place, the plastic spheres are dissolved with a solvent, leaving an open network of metallic struts.
“We’ve made foils of this metallic wood that are on the order of a square centimetre, or about the size of a playing die side,” James Pikul says. “To give you a sense of scale, there are about 1 billion nickel struts in a piece that size.”
Once the manufacturing method is developed, scientists can produce metallic wood in larger sizes and conduct various tests to know about mechanical properties in detail to enable this metallic wood for commercial purpose.
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