Materials as hard as snail teeth

Researchers want to harness the unusual wear resistance of limpet teeth for new types of materials.

The limpet lives on seashores.

The teeth of the limpet may be tiny, but they are enormously wear-resistant. The reason lies in the microstructure of the tooth, as an international team of researchers including physicists from the University of Leoben in Austria has discovered.

The limpet (Patella vulgata) lives on seashores: to feed, it scrapes algae from rocks in the surf with its micrometre-sized rasping teeth, which are located on the snail's tongue. To do this, it needs very hard and wear-resistant teeth. In the course of evolution, these have developed into the strongest biological materials of all.

Rare material behaviour

The researchers examined the animals' tiny teeth and observed a very unconventional and rare material behaviour: Normally, a material that is pulled lengthwise would expand and become thinner. In this case, however, it increased in thickness when stretched. In such - rare - cases, one speaks of auxetic materials.

According to the researchers, the next challenge is now to translate what they have learned from nature into technologically relevant materials. This is conceivable, for example, with modern methods of additive manufacturing, 3D printing, on a microscopic scale.

There are many applications for materials with high hardness and wear resistance: For example, in the tool industry, where drills or milling heads are coated with layers of very hard and wear-resistant materials to guarantee a longer service life and better cutting behaviour.

Written by: sda

Photos: Janek Pfeifer, Wikimedia Commons

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