One day soon, we won’t have to deal with any more smartphone spider-cracks or shattered glass.
This is all thanks to the mollusk shell.
Montreal’s McGill University Department of Mechanical Engineering’s research team, led by Prof. François Barthelat, were naturally inspired by the shellfish and have devised a new process that dramatically increases the fortitude of glass.
Using the technology available, they have created a glass that when dropped would become slightly deformed rather than shattered.
As most of us know, mother-of-pearl (or nacre) comes from the inside of a mollusk shell, such as abalone, mussel, or oyster. This shiny, iridescent material gives the shell its strength, as the rest of the shell is made almost entirely of calcium carbonate, which is brittle alone.
Barthelat’s team studied the internal structure of the nacre, which is compromised of individual, microscopic Lego-block pieces. During the research, it was discovered that the boundaries between the blocks are not straight at all, but look more wavy, like jigsaw puzzle pieces.
According to Barthelat, “Imagine trying to build a Lego wall with microscopic building blocks. It’s not the easiest thing in the world.”
Using microscopic glass, researchers replicated these boundaries using lasers to engrave 3D “micro-cracks” within them. These “micro-cracks” absorbed and dispersed the energy, when subjected to an impact, and kept the glass from shattering. These treated slides proved to be 200 times tougher than non-treated slides through the studies performed.
Barthelat and his team published their paper on this research in the journal Nature Communications.
Barthelat is now also working on trying to strengthen other brittle materials, such as ceramic and polymers.
Previous attempts to recreate the structures of nacre have proved to be challenging, Instead, what he and his team chose to do was to study the internal ‘weak’ boundaries or edges to be found in natural materials like nacre and then use lasers to engrave networks of 3D micro-cracks in glass slides in order to create similar weak boundaries. The results were dramatic.
The researchers were able to increase the toughness of glass slides (the kind of glass rectangles that get put under microscopes) 200 times compared to non-engraved slides. By engraving networks of micro-cracks in configurations of wavy lines in shapes similar to the wavy edges of pieces in a jigsaw puzzle in the surface of borosilicate glass, they were able to stop the cracks from propagating and becoming larger. They then filled these micro-cracks with polyurethane, although according to Barthelat, this second process is not essential since the patterns of micro-cracks in themselves are sufficient to stop the glass from shattering.
The researchers worked with glass slides simply because they were accessible, but Barthelat believes that the process will be very easy to scale up to any size of glass sheet, since people are already engraving logos and patterns on glass panels. He and his team are excited about the work that lies ahead for them.
“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,” says 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.”
For McGill University’s article, please go to:
McGill – Glass That Bends, But Never Breaks
Or read the full research paper:
F. Barthelot – ‘Overcoming the brittleness of glass through bio-inspiration and micro-architecture’