What is Ferrofluid: Definition and 23 Discussions

Ferrofluid is a liquid that is attracted to the poles of a magnet. It is a colloidal liquid made of nanoscale ferromagnetic, or ferrimagnetic, particles suspended in a carrier fluid (usually an organic solvent or water). Each magnetic particle is thoroughly coated with a surfactant to inhibit clumping. Large ferromagnetic particles can be ripped out of the homogeneous colloidal mixture, forming a separate clump of magnetic dust when exposed to strong magnetic fields. The magnetic attraction of tiny nanoparticles is weak enough that the surfactant's Van der Waals force is sufficient to prevent magnetic clumping or agglomeration. Ferrofluids usually do not retain magnetization in the absence of an externally applied field and thus are often classified as "superparamagnets" rather than ferromagnets.In contrast to ferrofluids, magnetorheological fluids (MR fluids) are magnetic fluids with larger particles. That is, a ferrofluid contains primarily nanoparticles, while an MR fluid contains primarily micrometre-scale particles. The particles in a ferrofluid are suspended by Brownian motion and generally will not settle under normal conditions, while particles in an MR fluid are too heavy to be suspended by Brownian motion. Particles in an MR fluid will therefore settle over time because of the inherent density difference between the particles and their carrier fluid. As a result, ferrofluids and MR fluids have very different applications.
A process for making a ferrofluid was invented in 1963 by NASA's Steve Papell to create liquid rocket fuel that could be drawn toward a fuel pump in a weightless environment by applying a magnetic field. The name ferrofluid was introduced, the process improved, more highly magnetic liquids synthesized, additional carrier liquids discovered, and the physical chemistry elucidated by R. E. Rosensweig and colleagues. In addition Rosensweig evolved a new branch of fluid mechanics termed ferrohydrodynamics which sparked further theoretical research on intriguing physical phenomena in ferrofluids. In 2019, researchers at the University of Massachusetts and Beijing University of Chemical Technology succeeded in creating a permanently magnetic ferrofluid which retains its magnetism when the external magnetic field is removed. The researchers also found that the droplet's magnetic properties were preserved even if the shape was physically changed or it was divided.

View More On Wikipedia.org
  1. EmeraldPlatypus

    I Force exerted by an iron core electromagnet on a ferrofluid

    I am trying more generally to find the equation of the fore exerted by an electromagnet. The one that I keep finding is F=((NI)^2 A mu0)/2X^2. N is turn number, I is current, Mu0 is permeability of free space, A is the area of the core and X is the distance from the electromagnet. I take...
  2. omega_minus

    A Effective Spring Constant of a Chain Polymer

    Hi All, I'm doing research in magnetic nanoparticles that are coated with chain molecules (oleic acid, I believe) and I am trying to model these molecules' effective spring constant. The basic scenario is this: When a water-based ferrofluid is evaporated, it leaves behind only dried...
  3. omega_minus

    Rotational dynamics of mono-domain magnetic nanoparticles

    Hi, I have a question about the rotation of a single-domain magnetic nanoparticle that is suspended in a ferrofluid immersed in an external field. Specifically, I am trying to work out the path that a normal vector on the surface of the sphere traces out in time. There are 2 ways the...
  4. itoero

    Creating Homemade Ferrofluid: Choosing the Right Solvent and Preventing Stains

    I ordered MICR toner powder and want to make a ferromagnetic fluid and keep it in a bottle. -First I need to make the ferrofluid. I mix MICR toner with vegetable oil (or oleic acid) or kerosene. Which of the two should I use? What's the difference? -I will put the ferrofluid in water. On...
  5. E

    Scientists make nanofibers using fridge magnet & ferrofluid

    Researches from the University of Georgia, Princeton University and Oxford University report a new method for nanofiber production using a permanent magnet and ferrofluid – magnetospinning. Results of this research are published in Advanced Materials journal -...
  6. ryanuser

    Fluid that is a permanent magnet at room temperature?

    Hi Is there any fluid that is a permanent magnet at room temperature? (Ferrofluids do not retain their magnetic effect hence temporary). Thanks
  7. O

    Why do ferrofluids form peaks in a magnetic field?

    Hello. I read that nanoparticles of ferrofluid are ferromagnetic, but they do not retain magnetization, so better is superparamagnetic. So, what is true? Is the particles ferromagnetic or paramagnetic? Why they don't retain magnetization? Thank you.
  8. E

    Ferrofluid in High Voltage AC Source

    What will happen in a ferrofluid in an elastic cylindrical tank when subjected to high voltage alternating current? Is it will expand and then back to its normal dimension periodically because of repulsion? The diagram on the attachment is the set-up, all answer will be appreciated. Thanks
  9. A

    Ferrofluid Used as MRI Contrast Agent: Heat Risk?

    so it seems ferrofluids might be used for mri scanners as contrast agents. Wouldn't the ferrofluid get hot?
  10. S

    Updated Ferrofluid Cell Pictures

    Hi Y'all, My name is Michael Snyder and I'm a PhD student at the University of Louisville. You may have seen my work on the 2012 APS calendar. A few years ago I posted some ferrofluid cell physics images in this forum. The cell is made of two pieces of glass and some ferrofluid...
  11. M

    Can a Magnetic Ferrofluid Valve Float Foam Balls in a Container?

    Hi, I was wanting to insert 1 inch foam balls inside a container of ferrofluid, causing the foam ball to float. A normal one-way water valve would not let the ball through without any leakage (I believe), therefore I think that If i can build a valvue that consists of a ring of neodynium...
  12. M

    Objects floating in Ferrofluid

    Hi, I've been thinking about ferroufluid and its application and whether anybody would be able to answer my questions. Is it denser or lighter than water. I know oil floats but it has iron in it. Surface tension of it. Reason I am asking about the surface tension is that I was wondering...
  13. C

    What are the potential uses for ferrofluids in interactive museum displays?

    Hi there; Right now I am currently in both a second level introductory college level Chemistry and Physics course. In chemistry, we have a semester project to do, and with a little physics background, we are going to create our own Ferrofluid. We need to figure out different things we can...
  14. S

    Can Ferrofluids Be Used in Tokamak or Spheromak Fusion Devices?

    Hi, Is it possible to use a ferrofluid to create a tokamak/spheromak? If not, then why? http://en.wikipedia.org/wiki/Ferrofluid Ferrofluids can be composed of non-magnetic liquids containing magnetic particles in colloidal suspension.
  15. A

    Can Ferrofluids Withstand 50 Psi Pressure?

    Hi to everyone, i wanted to ask if a ferrofluid exist that can withstand a pressure of 50 Psi? Does the "strenght" of the liquid depend on the strenght of the magnetiv field? Are there any such ferrofluids, or is this too much for the fluids available on the market? Thanks
  16. T

    Ferrofluid Display Cell construction- hydrophilic surface application help

    Greetings everyone, I'm constructing a ferrofluid display cell using FerroTech EFH1 ferrofluid inside of a round bottom pyrex beaker. The ferrofluid is oil based, so it is not hydrophilic. The liquid that the ferrofluid will be suspended in is Magnesium Citrate (a household laxative... and no...
  17. S

    Ferrofluid Cancer Treatment

    Could anyone possibly explain how ferrofluid is used in cancer treatment? Is it via an electromagnet or an alternating current? Have Googled but am none the wiser. Is ferrofluid difficult to warm up? What sort of temperatures are we talking about? Many thanks
  18. E

    Extended Essay - Rate of flow of ferrofluid

    I have just started working on my extended essay and my research question is "How does the rate of flow of ferrofluid through a thin tube depend upon the strength of the magnetic field" I have done one experiment where i changed the magnetic fields strength and measured the flow rate. The...
  19. L

    Measuring Viscosity of Ferrofluid: A Beginner's Guide

    Homework Statement I have a fluid dynamics question and I am hoping maybe you can help me with it. I haven't taken a fluids course yet so I am at a loss as to the solution, and all of the books I've looked through have left me empty handed. For my Experimental project i decided to measure the...
  20. T

    Exploring Ferrofluid Behavior with Magnets

    I understand the basics of Ferrofluid and how it works and reacts to a point. I have never had the chance to actually play with it to see the effects when magnets are applied. I understand that it (when used as a dampener) gets stiffer when the magnetic field is present. My question is...
  21. T

    Creating a Ferrofluid: A Guide for Scientists

    I have a box of iron fillings. Can I make a ferrofluid with this and if so what other things do I need?
  22. J

    Questions on Ferrofluid: Advantages, Delivery of Meds & Particle Sizes

    I recently did a lab report on ferrofluid for chemistry and am having difficulty with some questions. I was wondering if I could get some help. *Are there advantages to an oil-based ferrofluid compared to an aqueous ferrofluid? *Researchers have explored ways to attach medications to...
  23. N

    Finding Household Items for Ferrofluid Synhesis

    I would like to find a way to make a ferrofluid, and I think I have found a viable way using PCB etchant, steel wool, and ammonia to make Magnesite. At that point, I am wondering if there is anything more effective to do, starting from household items. Also, coating is needed. Wikipedia...