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Suspensions and Colloids

Suspensions and Colloids. Ishan Wathuthanthri iwathuth@stevens.edu Department of Mechanical Engineering Stevens Institute of Technology New Jersey, USA. Suspensions. Particles larger than ~1000nm. Separated by gravity. Examples (sand/water, dust/air). Making An Interesting Suspension.

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Suspensions and Colloids

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  1. Suspensions and Colloids Ishan Wathuthanthri iwathuth@stevens.edu Department of Mechanical Engineering Stevens Institute of Technology New Jersey, USA

  2. Suspensions • Particles larger than ~1000nm. • Separated by gravity. • Examples (sand/water, dust/air)

  3. Making An Interesting Suspension • Mix two parts cornstarch to one part water. • 100ml cornstarch (large beaker) • 50ml water (small beaker) • Place cornstarch into a ziploc bag and add water. • Close bag and mix. • Write down some characteristics of this suspension.

  4. Colloids • Particles upto ~100nm. • Cannot be separated by gravity

  5. Example of a Colloid- Ferrofluids • Ferrofluids- “ferro” iron. • Polarized in a magnetic field. • Colloidal mixture of iron particles suspended in a carrier fluid. • Generally particles ~10nm. Reference- L.Mao and H. Koser.

  6. History • Developed by NASA in the 1960’s. • Method of controlling fluids in space.

  7. Review of Magnetism

  8. Electromagnet

  9. Applications of Ferrofluids • Liquid seals in bearings. Used in hard drives/ o-rings.

  10. Speakers • Used for and cooling around coils.

  11. Dampening • Internal dampers in shock absorbers and stepper motors etc.

  12. Biomedical Application • Magnetic cell separation chambers

  13. Target delivery agents.

  14. Telescopes for Astronomy • Research conducted in using ferrofluids for liquid mirrors. http://www.newscientist.com/article/dn15154-morphing-mirror-could-clear-the-skies-for-astronomers.html?feedId=online-news_rss20

  15. Thank you. Questions?

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