Toner and magnet. Ferrofluid - what is it and how to make a ferromagnetic liquid yourself

To a person far from scientific discoveries, who said goodbye to physics or chemistry in school, many things seem unusual. Using in everyday life, for example, electrical appliances, we do not think about how exactly they work, taking the benefits of civilization for granted. But when it comes to something that goes beyond everyday perception, even adults are amazed, like children, and begin to believe in miracles.

How, apart from magic, can explain the appearance of volumetric figures, flowers and pyramids, magical pictures, replacing each other from a seemingly ordinary liquid? But it's not magic, science provides a rationale for what is happening.

What is a ferrofluid?

We are talking about a ferrofluid - a colloidal system consisting of water or other organic solvent containing the smallest particles of magnetite, and any material that contains iron. Their size is so small that it is even difficult to imagine: they are ten times thinner than a human hair! These microscopic indicators of magnitude allow them to be evenly distributed in the solvent using thermal motion.

For the time being, while there is no external influence, the liquid is calm, resembling a mirror. But one has only to bring a directed magnetic field to this "mirror", as it comes to life, showing the viewer amazing volumetric pictures: magical flowers bloom, moving figures grow on the surface, changing under the influence of the field.

Depending on the strength and direction of the influence of the magnetic field, the pictures change before our eyes - from light, barely noticeable ripples appearing on the surface of the liquid, through needles and peaks that change their sharpness and inclination and grow into flowers and trees.

The ability to create colorful pictures with the help of illumination, truly mesmerizing the observer, reveals an unknown world before him.

Unfortunately, metal particles, although they are called ferromagnetic, in the full sense are not such, since they cannot maintain the resulting shape after the disappearance of the magnetic field. Since they do not have their own magnetization. In this regard, the use of this discovery, which, by the way, is not entirely new - it was made by the American Rosenzweig in the middle of the last century, has not found wide application.

How to make and where is ferromagnetic fluid used?

Ferrofluids are used in electronics, in the automotive industry, and I want to believe that their widespread use is not far off, and with the development of nanotechnology, they will be widely used. In the meantime, it is mostly fun for the delighted audience, spoiled by various types of spectacles.

Three-dimensional pictures make you follow them, with bated breath, doubt whether this is a montage, and look for an explanation of what is happening, at least on the Internet. Who knows, maybe a little boy who today watches metal "natural" flowers and figures with his mouth open will tomorrow find a fundamentally new application for this phenomenon, making a revolution in science and technology. But this is tomorrow, but for now - watch and enjoy!

The toners found in printer cartridges have interesting magnetic properties, and you can experiment with them at your leisure. The effect of them turns out to be very interesting, because the liquid begins to reach for the magnet, and moreover, individual elements form bizarre geometric shapes. However, not all toners are suitable for repeating this step by step instructions... Only dark colored toners will be needed, since colored ones are made without using dark magnetic particles.

Materials

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

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

Step 1... Open the cartridge very carefully to empty the toner into the glass cup. You will need about 50 mm of liquid in total. To check if the liquid of your choice has magnetic properties, it is enough to run a magnet along the side of the glass. If it is activated, the experiment can be continued.

Toner liquid is not harmful to health if you do not inhale or drink it. That is why you need to wear protective gloves and a mask before this work. This will reduce the likelihood of poisoning if you accidentally spill liquid on your hands.

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

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 with the resulting magnetic fluid.

From the bottom of the plate, bring the magnet outside. Pay attention to what is happening inside the container. At the point of touching the magnet, the liquid should be collected by a hedgehog-shaped bulge. 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 bring a magnet from the back. By moving it from side to side, you will draw.

If you stain any objects or furniture with toner, wash it off with cold water, you should succeed without any problems. In no case should you use hot water, it will fix the pigment and it will be impossible to wash it.

Magnetic fluid has recently become more popular in online stores. Children love to play with her, although adults sometimes also enjoy playing with her. That is why we decided to devote this review to the manufacture of magnetic fluid with our own hands at home.

What do we need:
- vegetable oil;
- iron powder;
- capacity
- magnets.

According to the author of the idea, iron powder can be obtained with a file and a piece of iron. The first step is to pour the iron powder into the container. It should be noted that the more powder you have, the better, since the properties of a magnetic fluid are fully manifested in large quantities.

After that, you need to add quite a bit of vegetable oil.

Mix everything thoroughly. Best to stir with a wooden spoon or barbecue skewer.

After one and a half to two minutes of stirring, you will receive your magnetic fluid.

Note that when using, you need to be careful not to bring the magnet directly to the liquid, as it will stick and you will no longer be able to remove it from the magnet. Therefore, it is advised to do this through paper, plastic or something else.

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

Despite the name, ferromagnetic liquids do not exhibit ferromagnetic properties, since they do not retain residual magnetization after the disappearance of the external magnetic field. In fact [ ] ferromagnetic fluids are paramagnets and are often called "superparamagnets" because of their high magnetic susceptibility. Indeed, ferromagnetic fluids are currently difficult to create. [ ]

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Subtitles

Description

Ferromagnetic fluids are composed of nanometer-sized particles (typically 10 nm or less) magnetite, hematite, or other iron-containing material suspended in a carrier fluid. They are small enough that thermal motion distributes them evenly over the carrier fluid so that they contribute to the overall fluid response to the magnetic field. Likewise, 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 fluids are colloidal solutions - substances that have the properties of more than one state of matter. In this case, the two states are solid metal and the liquid in which it is contained. This ability to change state under the influence of a magnetic field allows ferromagnetic fluids to be used as seals, lubricants, and may also open up other applications in future nanoelectromechanical systems.

Ferromagnetic fluids are stable: their solid particles do not stick together and do not separate into a separate phase, even in a very strong magnetic field. Nevertheless, surfactants in a liquid tend to disintegrate over time (about several years), and eventually the particles stick together, stand out from the liquid and stop influencing the liquid's response to a magnetic field. Also, ferromagnetic fluids lose their magnetic properties at their Curie temperature, which for them depends on the specific material of the ferromagnetic particles, surfactants and carrier fluid.

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

Instability in a normally directed field

Under the influence of a rather 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 liquid, 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 fluids have a very high magnetic susceptibility, and a small bar magnet may be sufficient for the critical magnetic field to cause wrinkles on the surface.

Typical surfactants for ferromagnetic fluids

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

• sodium polyacrylate

Surfactants prevent particles from sticking together, preventing them from forming clusters that are too heavy, which 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 the molecules of the carrier liquid, forming, respectively, an ordinary or reverse micelle around the particle. As a result, spatial effects prevent particles from sticking together. Polyacrylic, citric acids 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 appearance of Coulomb repulsive forces between the particles, which increases the stability of the water-based liquid.

While surfactants are useful for prolonging the settling time of particles in a ferromagnetic fluid, they are detrimental to its magnetic properties (especially magnetic saturation of the fluid). The addition of surfactants (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. And although for some applications the viscosity of a ferromagnetic fluid in the activated state (so to speak, its "hardness") is not very important, for most commercial and industrial applications this is the most important property of the liquid, therefore a certain compromise is required between the viscosity in the activated state and the rate of particle settling ... The exception is surfactants based on polyelectrolytes, which make it possible to obtain highly concentrated liquids with low viscosity.

Application

Electronic devices

Ferrofluids are used in some tweeters to conduct heat away 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, being in contact with both magnetic surfaces and the coil at the same time.

Mechanical engineering

Ferrofluid is capable of reducing friction. When applied to the surface of a sufficiently strong magnet, such as neodymium, it allows the magnet to slide over a smooth surface with minimal resistance.

Defense industry

Aerospace industry

Medicine

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

Heat transfer

If you apply a magnetic field to ferromagnetic fluid with different susceptibility (for example, due to a temperature gradient) an inhomogeneous magnetic volumetric force occurs, 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 micro devices or in low gravity environments.

The use of a ferrofluid 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. Since ferromagnetic fluids are paramagnetic, they obey the Curie-Weiss law, becoming less magnetic as the temperature rises. A strong magnet located next to the voice coil, which generates heat, attracts cold liquid more than hot liquid, pulling hot liquid away from the coil to the cooler. It is an efficient cooling method that does not require additional energy input.

Generators

Frozen or polymerized ferromagnetic liquid, which is a combination of constant (magnetizing) and alternating magnetic fields, can serve as a source of elastic vibrations with the frequency of an 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

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INTRODUCTION

Purpose: prepare a ferromagnetic liquid and study its properties.

Tasks:

Learn about ferrofluid ( kind of non-newtonian fluid).

Prepare ferromagnetic liquid.

Conduct experiments to study its properties.

Find out its application.

To conclude.

Present the results.

Hypothesis: at home, you can prepare a ferromagnetic liquid and study its properties.

Scope of the results:participation in research competitions

Relevance:Magnetism is a physical phenomenon in which materials exert an attractive or repulsive force on other materials at a distance. Planet Earth has two magnetic poles and its own magnetic field. Magnets - an important part of our everyday life. Magnets are essential components of devices such as electric motors, speakers, computers, CD players, microwave ovens and of course cars. Magnets used in sensors, instruments, production equipment, scientific research. Ferromagnetic fluid is a type of non-Newtonian fluid. This is an artificially created liquid. This fluid changes properties under certain conditions that a person can control.

MAIN PART

2.1 Theoretical part

Magnetic fluids are a unique technological artificially synthesized material with fluid and magnetically controlled properties.

In 1963, NASA employee Steve Papell invented ferromagnetic fluid. He solved a very specific problem: how, in zero gravity, to force the liquid in the fuel tank of the rocket 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 - to add some magnetic substance to the fuel in order to control the movement of the fuel in the tank using an external magnet. So ferromagnetic liquid was born.

The minimum composition of a ferromagnetic fluid is a ferromagnet (for example, small particles of a magnetic metal) and a solvent (for example, various oils). But such a liquid will settle. To prevent this from happening, it is necessary to add a surface modifier (a substance that prevents the ferromagnet from sticking together, for example, citric acid). Ferromagnetic liquids are studied by the branch of science colloidal chemistry.

Magnetic fluid has all the advantages of a liquid material - a low coefficient of friction in contact with a solid, the ability to penetrate into microvolumes, the ability to wet almost any surface, etc. At the same time, magnetically controlled magnetic fluid allows you to hold it in the right place of the device under the influence of a magnetic field.

2.2 Practical part:

In the practical part of the work, I tried to make a ferromagnetic fluid and see how it changes in the presence of a magnet.

2.2.1 Materials and tools:

Toner powder, developer, iron shavings, magnetic powder;

Machine oil, sunflower oil;

Lemon acid;

Neodymium magnets: from a regular hard disk for a computer, from a sound speaker, a neodymium ring magnet purchased from a specialty store;

Bottle, funnel, various surfaces, plastic bag, gloves, stick;

Notepad, pen, camera, laptop.

2. 2.2 Experiment No. 1 Obtaining a ferromagnetic liquid from toner powder and machine oil

On the global Internet there are many sites that describe a method for producing ferromagnetic liquid from toner powder and machine oil in the proportion of one third of the toner powder, the rest is machine oil. I took brother laser toner powder and machine oil. Mixed in a plastic bottle. After mixing, I brought up the magnet and nothing happened. The liquid turned out, but it was not magnetic. If the liquid were magnetic, it would solidify and change its shape as the magnet moves. The experiment ended in failure.

2.2.3 Experiment No. 2 Obtaining ferromagnetic liquid from toner powder, developer and machine oil

From my first experience, I concluded that the toner used is not ferromagnetic. In modern laser printers, a developer, a special magnetic powder, is used to magnetize ink. In the resulting liquid in the first experiment, I added a third of the developer's volume. When I brought up the magnet, the liquid formed an almost imperceptible mound and not hardened. The result is a liquid with weak ferromagnetic properties. The experiment ended in failure.

2.2.4 Experience No. 3 Obtaining a ferromagnetic liquid from iron shavings and machine oil

After the first two failed experiments, I wondered about the power of the magnet. With which I check the presence of magnetic properties. To test the liquid, I used two magnets: a magnet from an audio speaker and a neodymium magnet from a no longer working hard disk drive (HDD). In order to make sure that a ferromagnetic liquid is not obtained due to the properties of a ferromagnet in a liquid, and not a magnet, I added ordinary iron filings to the resulting solution ( waste from work on a locksmith machine). The magnet attracted all the iron elements of the liquid to the wall! Magnetic properties appeared, but everything that I mixed can hardly be called liquid. The experiment failed again.

2.2.5 Experience No. 4 Obtaining a ferromagnetic liquid from magnetic powder and sunflower oil

So, a good ferromagnet is needed to obtain a ferromagnetic liquid! In the specialized store World of Magnets, I purchased a special iron magnetic powder for experiments.

2.2.6 Experience No. 5 Obtaining a ferromagnetic liquid from magnetic powder, citric acid and sunflower oil.

In order for the ferromagnetic liquid not to delaminate, a surfactant (surfactant) is added to it. I chose citric acid as a surfactant.

2.2.7 Experiment No. 6 Study of the properties of ferromagnetic liquid. Magnetic control.

To study the properties of the resulting liquid, I used a neodymium magnet.

2.2.8 Experiment No. 7 Study of the properties of ferromagnetic liquid. The ability to penetrate microvolumes(hole blockage )

In the last experiment, I tried to understand how it is possible to close the holes from leaks with the help of an external magnet. To do this, I first poured my liquid into a plastic flask with a large opening at the bottom. Then he brought the magnet to the wall next to the hole and lifted the flask. The liquid solidified by the magnet prevented the rest of the liquid from flowing out. As soon as I removed the magnet, everything leaked out of the flask.

2.3 Practical application

Application of ferromagnetic fluids:

1. On the basis of ferromagnetic liquid, radio-absorbing coatings are made for aircraft.
2. The creators of the famous Ferrari use magnetorheological fluid in the car's suspension: by manipulating a magnet, the driver can make the suspension more rigid or softer at any time.
3. Ferrofluids are used in some tweeters to conduct heat away from the voice coil. At the same time, it works as a mechanical silencer, suppressing unwanted resonance. The ferrofluid is held in the gap around the voice coil by a strong magnetic field while being in contact with both magnetic surfaces and the coil at the same time
4. Ferromagnetic fluids have many uses in optics due to their refractive properties. Among these applications is the measurement of the specific viscosity of a liquid placed between a polarizer and an analyzer, illuminated by a helium-neon laser.
5. As a working medium in tilt angle sensors and accelerometers.
6. In magnetic separators for separating and separating materials with different densities. Magnetic fluid has another amazing, truly unique property. In it, as in any liquid, bodies less dense float and bodies more dense than itself sink. But if you apply a magnetic field to it, then the drowned bodies begin to float. Moreover, the stronger the field, the heavier the bodies rise to the surface. By applying a magnetic field of varying strength, it is possible to make bodies float up with a given density. This property of the magnetic fluid is now used for ore beneficiation. It is drowned in a magnetic fluid, and then by an increasing magnetic field, first the waste rock is forced to float, and then heavy pieces of ore. For example, for the separation of gold and concentrate.
7. For cleaning water surfaces from oil products in case of emergency spills and disasters.
8. Printing and drawing devices. There are printing and drawing devices operating on magnetic fluid. A little magnetic fluid is added to the paint, and this paint is sprayed in a thin stream onto the paper stretched in front of it. If the jet is not deflected, a line will be drawn. But electromagnets are placed in the path of the trickle, like the deflecting electromagnets of a television picture tube. The role of the flow of electrons is played here by a thin trickle of paint with a magnetic fluid - it is the electromagnets that reject it, and letters, graphs, drawings remain on the paper.

3. CONCLUSION

conclusions

1. At home, you can prepare a ferromagnetic liquid and study its properties.
2. The success of the experiments depends on the strength of the magnet and the quality of the ferromagnet. When using toner powder or a printer developer, be sure it contains magnetic powder.
3. With the help of a magnet, you can see some of the properties of a ferromagnetic fluid and understand how different mechanisms work.

LIST OF USED SOURCES AND REFERENCES

1. How to make ferrofluid at home? Viktorova L.
2. ("Nizh", 2015, No. 12) https://www.hij.ru/read/issues/2015/december/5750/
3. MAGNETIC LIQUID, I. Senatskaya, Candidate of Chemical Sciences F. Bayburtsky https://www.nkj.ru/archive/articles/4971/ (Science and Life, MAGNETIC LIQUID)
4. Ferromagnetic liquid https://ru.wikipedia.org/wiki/%D0%A4%D0%B5%D1%80%D1%80%D0%BE%D0%BC%D0%B0%D0%B3%D0%BD % D0% B8% D1% 82% D0% BD% D0% B0% D1% 8F_% D0% B6% D0% B8% D0% B4% D0% BA% D0% BE% D1% 81% D1% 82% D1 % 8C
5. Ferrofluid - what is it and how to make a ferromagnetic fluid yourself http://www.sciencedebate2008.com/ferrofluid/