New Composites Formed Using Magnetic Particles

Composites are made by combining two different materials with different properties:

  • Concrete – concrete by itself is a composite of cement and crushed rock, which has a high strength against compression or crushing (like rock) but can be poured like a liquid into forms to create specific shapes before it hardens. Concrete does not have good strength against snapping or stretching, so materials like steel reinforcing rods are often added to it.
  • Fiberglass – the main component of fiberglass is a plastic resin or epoxy that is easy to shape while in liquid form and strong once solid, but quite brittle. In order to make it more flexible, glass fibers are added to the epoxy resin before it becomes solid. The end result is a product that is easy to form, light, strong, flexible and cheap.
  • A variety of other composites can be made by adding crystalline fibers and specialized forms of carbon to ceramics, metals and other substrates.

In each of these cases, the alignment and shape of the reinforcing substance can determine the strength of the final composite, and possibly other attributes as well. Steel rods that reinforce concrete are systematically laid in a matrix that is designed to add specific strength to the final product. Long thin single crystal fibers can also add a tremendous amount of strength to a composite but they are more difficult to align. As the reinforcing materials become smaller, the task of getting them correctly aligned becomes more complex.

Swiss scientists have developed a technique to create advanced composites by coating particles with iron oxide nanoparticles, then using magnetic fields to align them.

New family of composite structures – [ethz.ch]

Material scientists at ETH-Zürich are working on composite materials that mimic the structure of seashells. Such complex structures are produced using tiny magnetic particles which guide the composites’ stiffer elements into place. This technique enables new technologies from durable coatings to stronger and lighter materials.

Strengthening Polymer Composites With Magnetic Particles – [polymersolutions.com]

Scientists in Switzerland have used extremely low magnetic fields to align particles within composite polymers, thus reinforcing the structure in three dimensions. Though these materials probably won’t ever be used to hold up buildings, the researchers’ tests demonstrate that they are stronger and more resistant to wear than plain polymers so they could find use as specialized materials, reports Simon Hadlington for Chemistry World.

SEE ALSO:
Titanium Silk
Liquid Glass
Flexible Metamaterials

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