Do you remember those school times, when you used to experiment with those iron filings and magnets? It was amusing to see those tiny iron filings getting attracted to the magnet. Feeling the force and playing with those north and south poles of the magnet was fun, too. You all might be aware that the force is nothing but a magnetic field produced by the magnet to attract or repel other materials. It has a wide range of applications, and that’s why it is used in different sectors ranging from electronics to medicine. We use it in our everyday lives. Take the example of dishwashers, speakers, and refrigerators. And the fun fact is that you can never isolate the north and south poles of the magnet. Now, if the introduction has piqued your interest, let’s explore its different types.
Magnets are broadly classified into three types: Permanent, Temporary, and Electromagnet.
1. Permanent Magnets
As the name suggests, permanent magnets are those magnets that do not lose their magnetic properties. This means that the internal structure that is the atomic structure of these magnets is the one that generates the magnetic field. But it is not necessary that the permanent magnet cannot lose its magnetic properties. When put under external pressure, even these magnets can behave otherwise. The external pressure can be anything from high temperature to high stress. And if the permanent magnet is well-maintained, then it can function properly for years.
The permanent magnet is further classified into four types: Alnico, Ferrite, Neodymium Iron Boron, and Samarium Cobalt. The factors that separate these different types of permanent magnets are their materials, source of magnetism, and properties. Now let’s take a look at each of them in detail.
These magnets consist of main ingredients such as aluminum, nickel, and cobalt, and thus the name AlNiCo. The other ingredients that can be found in this magnet are copper and iron. It comes in different forms that are isotropic and anisotropic. The isotropic one can be magnetized in any direction, whereas the anisotropic one can only be magnetized depending on the direction of magnetization. The features that set Alnico magnets apart from others are their good temperature stability and high energy. It has applications in sensors, MRI, motors, and many more.
The ferrite magnet is made up of iron oxide and other metals, which are in chemical combination. And since it already consists of oxide, it cannot oxidize further, making it resistant to corrosion. Based on coercivity, the ferrite magnet is classified into soft and hard. The soft types are the ones that have low coercivity and are used in the electronics industry for transformers and inductors. Whereas, the hard types are the ones that have a high coercivity and are used in adhesive systems and electric motors. One of the notable features of a ferrite permanent magnet is that it can work well even in high temperatures. While the other magnet can demagnetize when put in a similar situation.
Neodymium Iron Boron
As the name implies, these magnets are made up of alloys of neodymium, iron, and boron, a few of the rare earth magnetic materials. It has a high energy product range, meaning even a small part can have high magnetic power. But on the other hand, it is brittle, so it shouldn’t be put under mechanical stress. This is to say that it has low mechanical strength. It is one of the strongest magnets in the market with high coercivity. The applications of this magnet range from different industries such as automobiles, power generators, electronics, and medical. One thing that needs to be kept in mind is that neodymium iron boron magnets have a low resistance to corrosion. So they must be coated with other metals and maintained well.
The Samarium cobalt magnet is similar to a rare earth permanent magnet, neodymium iron boron, with the difference that it is more resistant to corrosion. The distinguishing feature of this magnet is that it can maintain its magnetic properties in high as well as low temperatures. Like neodymium iron boron magnets, the samarium cobalt magnet is also brittle. With high mechanical stress, it can easily break. This is why it needs to be handled carefully. A few of the industries where this magnet is used are aerospace, military, food, automotive, and power.
2. Temporary Magnets
From the term temporary, you might have guessed that temporary magnets do not have magnetic power of their own. It relies on external force to create the magnetic field. And once the magnetic source is removed, it cannot retain its magnetism. It primarily comprises objects that can temporarily act as magnets. When the external magnetic field is brought into the picture, the atoms of the temporary magnets align to generate magnetic power.
Examples of temporary magnets are iron and nickel, which need an external magnetic field to attract. The other real-life application of temporary magnets is moving magnetic objects. It is used in cranes to lift magnetic objects from one place to another. Here, a permanent magnet cannot be used as it won’t detach from the magnetic materials.
The electromagnets create a magnetic field with the application of electricity. Here, the wires are coiled around a material. And depending on the type of material selected, the strength of the electromagnet varies. If non-magnetic material is used at the center, then the magnetic field will be weak. Whereas if the magnetic material is used instead then the magnetic field will be strong. They can be highly efficient and thus have wide applications.
When the electricity is passed through this setup, the coil of wire behaves like a magnet. And discontinuing the electric supply results in coils losing their magnetic ability. Since electromagnets can be easily turned on or off through electric supply, it is used in sectors such as research and industrial machinery that require controlling magnetic attraction. It is also used in the medical sector in Magnetic Resonance Imaging(MRI) machines. Additionally, it has applications in electronic components.