1. Magnetorheological Fluids Paul Longwell Hollidaysburg Area High School 2007 http://genchem.chem.wisc.edu/demonstrations/solid_state/pages/ferrofluids.htm

2. Magnetorheological Fluids o sometimes referred to as ferrofluids o often made by mixing ferromagnetic particles (iron, cobalt, etc) into a carrier fluid such as silicone oil or even water.

3. Magnetorheological Fluids –the ferromagnetic particles are forced into an aligned arrangement when the fluid is placed in a magnetic field

4. Magnetorheological Fluids –When the ferromagnetic particles are forced into alignment by the field, the shape of the fluid can be affected by the field lines.

5. Magnetorheological Fluids –The alignment of the particles in the fluid will also cause the viscosity of the fluid to increase, making the fluid seem “thicker.”

6. –MR fluids can consist of spherical particles, rod-shaped “nanowire” particles, or a combination of both. –Although spherical particles can be purchased commercially, nanowires particles are often synthesized in the laboratory. Part of this project involved making these nanowire particles. Making Magnetorheological Fluids

7. Making Nanowire Particles for the Fluid An alumina membrane is used as a template for the wires. The alumina disk is just a few hundred nanometers thick and is filled with pores that vary from 0.02  m to 20  m. By depositing ferromagnetic materials into these pores, nanowires are formed. http://www.2spi.com/catalog/spec_prep/filter2.shtmlhttp://www.whatman.com/products/?pageID=7.57.293

8. Making Nanowire Particles for the Fluid Before being placed in the electrodeposition cell, the membrane is coated with a layer of gallium indium to provide good electrical conduction.

9. Making Nanowire Particles for the Fluid A second electrode is placed in the opposite end of the cell and the depositing solution is poured in. In this case, a cobalt electrode and solution were chosen.

10. Making Nanowire Particles for the Fluid The pores of the alumina disk are now filled with cobalt. To extract the cobalt nanowires, the alumina membrane is dissolved in sodium hydroxide.

11. Making Nanowire Particles for the Fluid The cobalt nanowires are now rinsed and stored under a vacuum in vials.

12. Analyzing Magnetorheological Fluids The cobalt nanowires are suspended in ethanol and placed on a silicon chip. For comparison, one chip is placed in a magnetic field while the other is not.

13. Analyzing Magnetorheological Fluids The chips are loaded into a Scanning Electron Microscope (SEM) for analysis.

14. Analyzing Magnetorheological Fluids Nanowires arranged in the absence of a magnetic field Nanowires aligned in a field of approximately 1 Tesla.

15. Analyzing Magnetorheological Fluids A mixture of nanowires and spherical particles arranged in the absence of a magnetic field A mixture of nanowires and spherical particles aligned in a field of approximately 1 Tesla.

16. Applications of MR Fluids

20. Thank You Dr. Richard Bell The Pennsylvania State University, Altoona College Chemistry Department