In the early nineties of the last century, the film “Terminator 2” was released on cinema screens. All viewers were amazed by the ability of the cyborg killer made of viscous metal, played by Robert Patrick, to take on a variety of guises.

Back then, admiring professionally made computer animation, we did not think about the fact that the effect of the fantastic transformations of a cyborg killer can be simulated in real conditions.

Ferromagnetic fluid is the material that allows you to see moving sculptural compositions. All substances can be attracted or repelled to the classical one. But the reaction of most of them is so weak that it can only be detected with special devices. It would be great if it were possible to increase materials without destroying their structure and radically changing their original properties.

Everything changed when chemists intervened in solving this issue and created ferromagnetic liquids with good fluidity. They were able to obtain the smallest magnetic particles that were introduced into liquids, and when exposed to a magnetic field, they did not bunch up and settle, but made the liquid “solid.”

Ferromagnetic fluid is a colloidal dispersion of very small particles stabilized in an aqueous or hydrocarbon medium, supported by surfactants. Such liquids are stable for several years and have good fluidity in combination with magnetic properties.

Ferromagnetic fluid can be produced in many ways. The process is quite simple and consists of two stages. First, it is necessary to obtain magnetic particles with sizes close to colloidal. And the next step is to stabilize them in a liquid base.

The topic of the possibility of practical use of such liquids remains very relevant for researchers. IN recent years they are working on treating wastewater with such liquids from petroleum products. The principle of this process is the magnetization of petroleum products by introducing magnetic fluids into waste water. And then the magnetized petroleum products are separated by special systems.

Ferromagnetic fluid will also find its application in medicine. For example, anticancer medications harm healthy cells. But if you mix medications with such a liquid and inject it into the patient’s blood, and place a magnet near the tumor, the mixture will concentrate in the right place and will not damage the entire body.

Here's another example. Companies that produce shock absorbers pour ferromagnetic fluids into their shock absorbers. An electromagnet connected to them instantly makes the liquid viscous or fluid. In this way, the car's suspension is adjusted.

Such liquids also have interesting properties. If you miss sound wave through the magnetized liquid, then in the one located nearby, an electric driving force arises. And one more thing. If you add magnetic liquid to the solution for soap bubbles, you will get a mesmerizing performance.

The toners found in printer cartridges have interesting magnetic properties that you can experiment with at your leisure. The effect they produce is very interesting, because the liquid begins to be drawn towards the magnet, and moreover, individual elements form bizarre geometric shapes. True, not all toners are suitable for repeating this step by step instructions. Only dark-colored toners will be needed, since color toners are made without the use of dark magnetic particles.

Materials

To make magnetic fluid with your own hands, you will need:

• thick sheet of paper;
• protective gloves;
• protective mask;
• empty glass cup;
• plastic sticker for stirring;
• vegetable oil;
• spoon;
• a wide plastic container, such as a plate.

Step 1. Very carefully open the cartridge to pour the toner from it into a glass cup. In total you will need about 50 mm of liquid. To check whether the liquid you have chosen has magnetic properties, just run a magnet along the wall of the glass. If it is activated, the experiment can continue.

The toner liquid is not harmful to your health unless you inhale or drink it. This is why you need to wear protective gloves and a mask before doing this work. This way you will reduce the likelihood of poisoning if liquid accidentally gets on your hands.

Step 2. You must add two tablespoons to the volume of goods you have already received. vegetable oil. Using a plastic sticker, thoroughly mix the mixture you have received. To continue the experiment, it must be homogeneous.

Step 3. You need to carefully pour the resulting magnetic fluid into a wide container. This is exactly what is needed to see everything that will happen to the resulting magnetic fluid.

Apply a magnet from the bottom of the plate to the outside. Pay attention to what is happening inside the container. At the point of contact of the magnet, the liquid should be collected in a voluminous tubercle in the shape of a hedgehog. These are the magnetic particles that manufacturers add to the toner. They can be smaller or larger, which again depends on the manufacturer.

Step 4. With this liquid you can make a magnetic pattern. To do this, you need to pour some of the liquid onto thick paper and hold a magnet on the back side. By moving it from side to side, you will draw.

If you stain any objects or furniture with toner, wash everything off cold water, you should be able to do this without any problems. hot water Under no circumstances should you use it, it will fix the pigment and it will be impossible to wash it out.

(surfactant) that forms a protective shell around the particles and prevents them from sticking together due to van der Waals or magnetic forces.

Despite their name, ferromagnetic liquids do not exhibit ferromagnetic properties because they do not retain residual magnetization after the disappearance of the external magnetic field. In fact [ ] Ferromagnetic liquids are paramagnetic and are often called “superparamagnetic” due to their high magnetic susceptibility. It is currently difficult to create truly ferromagnetic liquids. [ ]

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Ferromagnetic fluid/Ferrofluid

How to make ferrofluid from sparklers!Ferromagnetic liquid!How to make ferrofluid

MAGNETIC FLUID LIQUID METAL ferrofluid IGOR BELETSKY

How to make MAGNETIC FLUID

Subtitles

Description

Ferromagnetic fluids consist of nanometer-sized particles (typical size 10 nm or smaller) of magnetite, hematite, or other iron-containing material, suspended in a carrier fluid. They are small enough that thermal motion will distribute them evenly throughout the carrier fluid so that they contribute to the response of the fluid as a whole to the magnetic field. Similarly, ions in aqueous solutions of paramagnetic salts (for example, an aqueous solution of copper(II) sulfate or manganese(II) chloride) impart paramagnetic properties to the solution.

Ferromagnetic liquids are colloidal solutions - substances that have the properties of more than one state of matter. In this case, the two states are the solid metal and the liquid in which it is contained. This ability to change state under the influence of a magnetic field allows the use of ferromagnetic fluids as sealants, lubricants, and may also open up other applications in future nanoelectromechanical systems.

Ferromagnetic liquids are stable: their solid particles do not stick together and do not separate into a separate phase even in a very strong magnetic field. However, surfactants in a liquid tend to disintegrate over time (approximately several years), and eventually the particles will stick together, separate from the liquid, and no longer affect the liquid's response to a magnetic field. Also, ferromagnetic liquids lose their magnetic properties at their Curie temperature, which for them depends on the specific material of the ferromagnetic particles, the surfactant and the carrier liquid.

The term "magnetorheological fluid" refers to fluids that, like ferromagnetic fluids, solidify in the presence of a magnetic field. The difference between ferromagnetic fluid and magnetorheological fluid is the particle size. The particles in a ferromagnetic fluid are mainly nanometer-sized particles that are suspended due to Brownian motion and do not settle under normal conditions. Particles in a magnetorheological fluid are mostly micrometer-sized (1-3 orders of magnitude larger); they are too heavy to be suspended by Brownian motion, and so settle over time due to natural differences in the density of the particles and the carrier fluid. As a result, these two types of fluids have different applications.

Instability in a normally directed field

Under the influence of a fairly strong vertically directed magnetic field, the surface of a liquid with paramagnetic properties spontaneously forms a regular structure of folds. This effect is known as " instability in a normally directed field" The formation of folds increases the free energy of the surface and the gravitational energy of the fluid, but decreases the energy of the magnetic field. This configuration occurs only when the critical value of the magnetic field is exceeded, when the decrease in its energy exceeds the contribution from the increase in the free energy of the surface and the gravitational energy of the liquid. Ferromagnetic liquids have very high magnetic susceptibility, and a small bar magnet may be sufficient for a critical magnetic field to cause wrinkles on the surface.

Typical surfactants for ferrofluids

To envelop particles in a ferromagnetic fluid, in particular, the following surfactants are used:

• sodium polyacrylate

Surfactants prevent particles from sticking together, preventing them from forming clusters that are too heavy and cannot be held in suspension due to Brownian motion. In an ideal ferromagnetic fluid, magnetic particles do not settle even in a very strong magnetic or gravitational field. Surfactant molecules have a polar “head” and a non-polar “tail” (or vice versa); one of the ends is adsorbed to the particle, and the other is attached to molecules of the carrier liquid, respectively, forming a regular or reverse micelle around the particle. As a result, spatial effects prevent particles from sticking together. Polyacrylic, citric acid and their salts form an electric double layer on the surface of the particles as a result of the adsorption of polyanions, which leads to the emergence of Coulomb repulsive forces between the particles, increasing the stability of the water-based liquid.

Although surfactants are useful for prolonging the settling time of particles in a ferromagnetic liquid, they are harmful to its magnetic properties (in particular, to the magnetic saturation of the liquid). The addition of a surfactant (or other foreign substances) reduces the packing density of ferromagnetic particles in the activated state of the liquid, thereby reducing its viscosity in this state, giving a “softer” activated liquid. Although for some applications the activated viscosity of a ferromagnetic fluid (its “hardness,” so to speak) is not very important, for most commercial and industrial applications it is the most important property of the fluid, so some compromise is required between activated viscosity and particle settling rate . An exception is surfactants based on polyelectrolytes, which make it possible to obtain highly concentrated liquids with low viscosity.

Application

Electronic devices

Ferromagnetic fluids are used to create liquid sealing devices around rotating axes in hard drives. The rotating axis is surrounded by a magnet, and a small amount of ferromagnetic fluid is placed in the gap between the magnet and the axis, which is held by the attraction of the magnet. The liquid forms a barrier that prevents particles from the outside from entering the hard drive. According to engineers Ferrotec Corporation, liquid seals on rotating axles normally withstand pressures of 3 to 4 psi (about 20 to 30 kPa), but such seals are not very suitable for linear motion components (such as pistons), since the liquid is mechanically drawn out from the gap.

Ferromagnetic fluid is also used in some tweeters to remove heat from the voice coil. At the same time, it works as a mechanical damper, suppressing unwanted resonance. The ferromagnetic fluid is held in the gap around the voice coil by a strong magnetic field, while simultaneously being in contact with both magnetic surfaces and the coil.

Mechanical engineering

Ferromagnetic fluid can reduce friction. When applied to the surface of a sufficiently strong magnet, such as neodymium, it allows the magnet to glide over a smooth surface with minimal resistance.

Defense industry

Aerospace industry

Medicine

Many experiments are being conducted on the use of ferromagnetic fluids to remove tumors.

Heat transfer

If a magnetic field is applied to a ferromagnetic fluid with different susceptibility (for example, due to a temperature gradient), a non-uniform magnetic volume force arises, which leads to a form of heat transfer called thermomagnetic convection. This form of heat transfer can be used where conventional convection is not suitable, such as in microdevices or in reduced gravity environments.

The use of ferromagnetic fluid to dissipate heat in speakers has already been mentioned. The liquid occupies the gap around the voice coil, held in place by the magnetic field. Because ferromagnetic liquids are paramagnetic, they obey the Curie-Weiss law, becoming less magnetic as the temperature increases. A strong magnet located near the voice coil, which produces heat, attracts cold fluid more than hot fluid, drawing the hot fluid away from the coil and towards the cooler. This effective method cooling, which does not require additional energy consumption.

Generators

A frozen or polymerized ferromagnetic fluid, located in a combination of constant (magnetizing) and alternating magnetic fields, can serve as a source of elastic vibrations with the frequency of the alternating field, which can be used to generate ultrasound.

Mining industry

Ferromagnetic fluid can be used as part of a magnetic fluid separator for cleaning

The magic and magic of magnetic fluid is simply amazing! Anyone can create fantastically beautiful patterns and sculptures without much difficulty. This is a great physical toy for stress relief and more.

To make magnetic fluid you will need only two components: iron powder and machine or vegetable oil, preferably with minimal viscosity. All you have to do is combine them and apply a magnet and a miracle will happen. This is all very funny, but there is also a pragmatic application. Of course, and more than one! For example, magnetic fluid has long been used as a seal for rotating shafts, which can significantly increase the service life of mechanisms and reduce noise levels. In addition, there are non-leakage magnetic lubricants, magnetic shock absorbers, and magnetic valves. Magnetic fluid has even been used in medicine. And, of course, magnetic paint. And this is not the entire list. Both beautiful and useful. You can buy a powerful magnet in a Chinese online store. Read more interesting material O .

How to make ferrofluid

In this video you will see a very beautiful and interesting experiment of a chemical reaction between a magnet and printer ink.

discussion

papixs
Anyone who has dealt with toner understands that toner is “solid water.” If, when you are refilling a cartridge, and you accidentally pull the toner bottle, it scatters all over the room; if there is even a 0.01 mm hole in the cartridge, the toner spills out through this nano hole. In short, this toner is a terrible thing.

Sergey
you take a magnet, burn a fire from old boards, the ash is full of tiny dust that is magnetized to the magnet, thus you get the smallest magnetic powder.

Danil Stepanyuk
alex saps toner is suitable for laser printers, you take it and take sunflower oil and mix it and you get magnetic fluid. Glad to help.

Vitali mikhaliuk
I needed a lot (a couple of liters) and buying it in such a volume was expensive. I used these instructions. I found a kilogram of fcpc toner from hp (at one time I was refilling printers and there was just a can lying around). By the way, there were several cans of toner. Which one to use was determined as follows: I simply took neodymium magnets and attached them to the can. To which he was magnetized with greater force, he took it.

I poured in sunflower oil and stirred - I got what I wanted. But they have already written correctly here: you won’t get any beauty, moreover, if it sits for a while, there will be sediment. And this is unacceptable in many cases. For my purposes it was quite suitable, perhaps - later I’ll post a video showing what I did.

The developer didn't go. Of course, it’s very cool that it actually magnetizes very strongly, the neodymium magnet cannot be torn off from the can. But the grains are too large, they constantly fall into sediment and do not hold a film around them. But I still couldn’t figure out how to split it up (however, I didn’t even try; I probably could have come up with something).

It's been 52 years since NASA employee Steve Papell invented ferrofluid. He was solving a very specific problem: how, in conditions of weightlessness, to force the liquid in the rocket’s fuel tank to approach the hole from which the pump pumped fuel into the combustion chamber. It was then that Papell came up with a non-trivial solution - adding some kind of magnetic substance to the fuel in order to control the movement of fuel in the tank using an external magnet. This is how ferromagnetic liquid was born.

Papell used magnetite (Fe 3 O 4) as a magnetic substance, which he crushed using a special technology (ground in a mixture with oleic acid) for many days. The result was a stable colloidal suspension in which tiny particles of magnetite 0.1-0.2 microns in size stably existed. Oleic acid in this system played the role of a surface modifier, which prevented magnetite particles from sticking together. S. Papella's patent US 3215572 A (Low viscosity magnetic fluid obtained by the colloidal suspension of magnetic particles) is open and can be viewed on the Internet. The classic composition of a ferromagnetic fluid is 5% (by volume) magnetic particles, 10% surface modifier (oleic, citric or polyacrylic acid, etc.). The rest is organic solvent, including liquid oils.

Interest in magnetic fluids has revived in recent years, and today they have already found many applications. If you apply such a liquid to a neodymium magnet, the magnet will slide over the surface with minimal resistance, that is, friction will sharply decrease. Radio-absorbing coatings for aircraft are made in the USA based on ferromagnetic fluid. And the creators of the famous Ferrari use magnetorheological fluid in the car’s suspension: by manipulating the magnet, the driver can make the suspension harder or softer at any time. And these are just a few examples.

Magnetic fluid is an amazing material. Once you place it in a magnetic field, the scattered magnetic particles unite and line up along the field lines, turning into a completely solid substance. Today, tricks with magnetic fluid, which upon contact with a magnet turns into hedgehogs or cacti that are impeccable in terms of symmetry, are shown on many entertainment shows. Of course, you can buy ferromagnetic fluid, but it’s much more interesting to make it yourself.

We wrote about how to obtain a self-hardening magnetic fluid, which will allow you to examine the structures formed by magnetic particles under a microscope (“Chemistry and Life”, 2015, No. 11). And here is another recipe for a homemade ferromagnetic fluid. Take 50 ml of laser printer toner. This powder consists of at least 40% magnetite, the particle size of which is 10 nanometers or less. The toner also necessarily contains a surface modifier so that the nanoparticles do not stick together. Add 30 ml of vegetable oil (two tablespoons) to 50 ml of toner and mix thoroughly, sparing no time in this process. The result will be a black homogeneous liquid, similar to sour cream. Now pour it into a flat glass container with sides so that the layer thickness is at least a centimeter. Place a magnet under the bottom of the container, and a hard hedgehog will immediately appear in the liquid at this point. It can be moved using a magnet. If you bring a magnet to the surface of the liquid or from the side, the liquid will literally jump out towards the magnet, so be careful. To avoid this problem, you can place the magnetic fluid in a small glass conical flask, filling it halfway or a little less. Tilt the flask to create a layer of liquid along the side of the flask and hold the magnet close to the glass.

Success depends on the strength of the magnet (neodymium magnet small size can be bought in stores) and toner quality. IN the latter case you need to be sure that it contains magnetic powder.