When it comes to metallurgy, it is common knowledge that small grains make for hard metals. But how do you actually get these grains?
A group of researchers from Brown University has found a way to destroy individual metal nanocouples that lead to metals that are up to four times harder than naturally occurring structures. This new method is quite different from traditional hardening techniques.
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“Hamming and other hardening methods are all top-down ways to change grain structure, and it’s much harder for you to control grain size,” said Chen, Brown, and assistant professor of chemistry, in a press release . Of new research.
“All we have done is nanoparticle building blocks that fuse together when you squeeze them. In this way we can have similar grain sizes that can be fine for cultured properties. “
For this research, the team used gold, silver, palladium, and other metal nanoparticles and chemically stripped them of organic molecules called ligands, which typically prevent metal-metal bonds to form between the particles. . The clusters were then able to fuse together with only a slight pressure.
New metal coins made with the technique found electrical conduction and light reflection to be almost identical to standard metals, but their optical properties changed dramatically.
Chen stated that “known as the plasmonic effect, gold nanoparticles are actually purple-black in color.” “But when we applied the pressure, we see that these purple flakes suddenly turn into bright gold. One of the ways we knew that we actually formed bulk gold. “
Researchers are now looking to apply the technique to commercial products because chemical treatment is relatively simple to perform. Chen has currently patented the technology and has “great potential both for the industry and for the scientific research community.”