Jul
08
2007

A scientist talks about super-strong natural materials without bringing up bulletproof vests. Neat.

Things That Nature Does Not Fully Understand

  1. Dippin’ Dots
  2. Anime
  3. Nuclear Power Plants
  4. Internet Dating
  5. Stephen Baldwin

Things That Science Does Not Fully Understand

  1. Fireflies
  2. Photons
  3. Stephen Baldwin
  4. The Slinky
  5. Abalone Shells

Science is working on this last item, though (while Nature doesn’t even know where to begin with “Dippin’ Dots”).

Abalone shells, it just so happens, are very, very strong. They are made up of aragonite (which itself is composed of calcium carbonate, the stuff in all seashells), but the shells are 3000 times more fracture-resistant that aragonite alone. This article gives points out that you could run over an abalone shell with a truck, and it wouldn’t break; “you will crumble the outside [of the shell] but not the [nacre] inside.” Exactly how this “nacre” forms is something that has been puzzling scientists.
The Mighty Abalone: Will we ever learn your secrets?    (photo by rachaelwrite)
The Mighty Abalone: Will we ever learn your secrets? (photo by rachaelwrite)

It had been thought that the microscopic structure of nacre was something like a wall bricks or tiles stacked regularly on top of each other – aragonite bricks, with organic mortar between them. However, after having examined nacre using synchrotron radiation, or “light emitted by electrons speeding around a curved track,” scientists think that the bricks and mortar analogy might not be quite accurate.

It seems now that the “wall” is largely composed of “distinct clumps of bricks, each an irregular column of crystals with identical composition but a crystal orientation different than neighboring columns.” Scientists think the reason for this irregular structure has to do with eliminating natural planes of cleavage. “A poly-crystal,” the researchers say, “is mechanically stronger than a single crystal, so perhaps that is an advantage for the animal."

What’s more, the process for constructing the nacre is extremely efficient. The aragonite crystals, composing 95% of the structure, are self-assembled, so the organism has to manufacture only the organic mortar between them.

If we could find a synthetic way of copying biominerals like this, they could be applied in all sorts of places. “We could, for example, produce cars that absorb all the energy at the impact point but do not fracture,” says one University of Wisconsin-Madison scientist. Neat.

Your Comments, Thoughts, Questions, Ideas

bryan kennedy's picture

Natural nanotech
While the structure that gives abalone its strength is built on the "micro" scale--millionths of a meter--this research is similar to scientists' work in nanotechnology--billionths of a meter. They are taking hints from these natural wonders and trying to build new structures based on nature's exemplary phenomenon.

This all reminds me of a cool quote from New York Times reporter Henry Fountain. "Nature was nano before nano was cool."

posted on Sun, 07/08/2007 - 12:21pm

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