(The Wilkins Ice Shelf. Source: twilightearth.com)
Sometimes the materials science industry can take a cue from mother nature and discover something that was previously untapped, yet right in front of our faces. A few years back, a group of scientists at Lawrence Berkeley National Laboratory used mother-of-pearl as a model for the creation of advanced ceramic materials. Mother-of-pearl, or "Nacre", is a naturally-occurring ceramic that is mostly found as reinforcement in mollusk shells. The team at Berkeley devised a way to emulate the structure of Nacre using the process of water freezing as a guide. An article from Chemical and Engineering News describes their process:
"The researchers knew that when saltwater freezes, it can form tiny plates of ice. Impurities in the water are squeezed out as the plates form and become trapped in the spaces between them. [The group at Berkeley] exploits this behavior using concentrated suspensions of ceramic particles in water. As the water freezes, it pushes the ceramic particles into the layers between the ice plates. The rate of freezing determines the thickness of the resulting ceramic layers, which can range from 1 to 200 µm."
The ice is then removed by the process of freeze-drying, leaving a ceramic scaffold behind with ice plate-shaped pores. After stabilization, the pores can be filled with a secondary compound (examples in the article include epoxy and aluminum alloy, but there are several options). John Halloran, a materials scientist at the University of Michigan described the results of the project as displaying "remarkably improved mechanical properties" compared to standard ceramics developed from today's processes. This discovery has several applications, including the possibility of devising bone substitutes that are four times stronger than the current industry standard.
To read the full article from Chemical and Engineering News, follow the link:
To learn more about porous ceramics applications, check out Refractron:
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