Scientists Create Tough Glass That Bends And Deforms Instead Of Shattering
Drop a wine glass on the floor and you know what happens next: glass everywhere, annoying cleanup, a minuscule shard that you invariably miss and step on later. But if scientists at McGill University in Canada have their way, all that will one day be a thing of the past. A team led by mechanical engineer François Barthelat has created a glass that bends and becomes deformed instead of shattering. Their inspiration? Mollusks.
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"Mollusk shells are made up of about 95 per cent chalk, which is very brittle in its pure form," said Barthelat. "But nacre, or mother-of-pearl, which coats the inner shells, is made up of microscopic tablets that are a bit like miniature Lego building blocks, is known to be extremely strong and tough, which is why people have been studying its structure for the past twenty years."
The McGill team studied the "weak," brick-like boundaries found in nacre, a material which is 3,000 times more break-resistant than the mineral from which it is made, aragonite. Barthelat and his colleagues engraved 3D, nacre-inspired "micro-cracks" on the kind of glass slides you use under a microscope. It may seem counterintuitive to add cracks to something to strengthen it, but it turns out that such cracks actually increased the toughness of the glass 200 fold. That's because the cracks, arranged in jigsaw-puzzle-like waves, prevent unintentional cracks from spreading and shattering the glass.
The McGill scientists only tested their micro-crack method on glass slides, but Barthelat says that the engraving process would be simple to scale up to larger materials like drinking glasses. The method could even be used for non-glass materials like ceramics, too.
"What we know now is that we can toughen glass, or other materials, by using patterns of micro-cracks to guide larger cracks, and in the process absorb the energy from an impact," said Barthelat. "We chose to work with glass because we wanted to work with the archetypal brittle material. But we plan to go on to work with ceramics and polymers in future. Observing the natural world can clearly lead to improved man-made designs."
Barthelat and his team detailed their findings in a study titled "Overcoming the brittleness of glass through bio-inspiration and micro-architecture," which was published yesterday in the journal Nature Communications.
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