Engraving microscopic cracks in glass sheets can make it 200 times tougher than normal, McGill University mechanical engineers say. The insight could lead to improvements in regular glass objects like wine glasses or jars that don’t shatter when dropped, instead only deforming on impact.
Researchers took a clue from nature to uncover the fact that etching wavy lines in test glass slides prevented stress-induced cracks from spreading into the material’s failure. Their muse was the seemingly simple mother-of-pearl coating inside the shells of some mollusks.
This material is called nacre, and it is mostly composed of chalk, a brittle substance that normally disintegrates under the slightest pressure. But the organism constructs a biomaterial that is 3,000 times tougher than the weak chalk from which it is composed, writes François Barthelat, who runs McGill’s biomimetic materials lab and led the research. The secret is in how the creature builds nacre out of tiny tablets of chalk that are laid down in offset rows. This architecture, which is also seen in teeth and bones, counters a propagating crack by deflecting it and diffusing energy to surrounding tiles.
These pictures, courtesy of NASA’s Jet Propulsion Laboratory, show the results of the Mars rover Curiosity’s first drilling operations that occurred in mid-February. The central hole above was drilled on Feb. 8 into a rock called “John Klein” where the rover attempted its first sample. The hole is 0.63 inch in diameter and 2.5 inches deep. Curiosity drilled the more shallow hole to the right two days before as a test of the equipment.
The next day, a laser mounted on the rover’s Chemistry and Camera instrument burned 10 spots—labeled in red in the picture above—into the rock powder drilled the day before. The electromagnetic signature resulting from the laser pulses burning the freshly ground rock were analyzed to help scientists understand the mineral composition of Mars.