Magnetorheological Fluids

Paul Longwell

Hollidaysburg Area High School

2007

http://genchem.chem.wisc.edu/demonstrations/solid_state/pages/ferrofluids.htm

Magnetorheological Fluidso sometimes referred to as ferrofluidso often made by mixing ferromagnetic particles (iron,

cobalt, etc) into a carrier fluid such as silicone oil or even water.

Magnetorheological Fluids– the ferromagnetic particles are forced into an aligned

arrangement when the fluid is placed in a magnetic field

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.

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.”

– 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

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 0.02m to 20m. 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

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.

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.

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.

Making Nanowire Particles for the Fluid

The cobalt nanowires are now rinsed and stored under a vacuum in vials.

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.

Analyzing Magnetorheological Fluids

The chips are loaded into a Scanning Electron Microscope (SEM) for analysis.

Analyzing Magnetorheological Fluids

Nanowires arranged in the absence of a

magnetic field

Nanowires aligned in a field of approximately 1

Tesla.

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.

Applications of MR Fluids

Applications of MR Fluids

Applications of MR Fluids

Applications of MR Fluids

Thank You

Dr. Richard BellThe Pennsylvania State University, Altoona College

Chemistry Department