First there were ferit magnets.
Classic ferrite magnets known to us since childhood. Probably everyone played with magnets, admiring their strength. Some samples were quite strong, they were used to create powerful speakers, from where they were most often extracted by curious children. The bonding strength of ferrite magnets is quite high, there is a relationship between the dimensions and the bonding layer. Ferrite magnets have been used for a variety of purposes, including industrial ones. Their main advantages were:
- Resistance to corrosion and atmospheric moisture;
- Resistance to demagnetization;
- Low cost of production;
- Easy to machine.
- As for the shortcomings, they are as follows:
- Weak magnetic field;
- Fragility, lack of resistance to blows.
The basis of ferrite magnets is the natural material magnetite, which is subjected to appropriate processing - additives such as cobalt oxide are added to it. The first ferrite magnets contained barium, subsequently replaced by strontium, which made the manufacture of magnets cheaper and easier. In subsequent years, the technology for manufacturing ferrite magnets was improved, but it was impossible to achieve a very high adhesion force. A radical change in the technology of magnet production took place in the 1980s, when the first neodymium magnets appeared, which significantly exceeded their ferrite counterparts by the coercive force.
Then a neodymium magnet appeared
Neodymium magnets were originally produced in Japan and the United States of America. They were discovered in the research laboratories of these countries and are a combination of the following chemical elements: boron, iron and metal from the lanthanoid group - neodymium. This chemical element belongs to the rare earth group and is the main link in the neodymium magnet. The element boron is added to the magnets in fairly small quantities. The bonding strength of neodymium magnets is incredibly high, it significantly exceeds the bonding strength of ordinary ferrite magnets. If you take two large pieces of neodymium alloy and ensure that they are in contact with each other, then breaking them with your bare hands will be almost impossible.
The first neodymium magnets went on sale in the 1990s. They were and remain quite expensive, the cost of the most powerful samples reaches several thousand rubles. This is due to the fact that the amount of neodymium in the rock workings is small. This is what affects the final cost. In addition, developer patents have an effect on cost.
What are neodymium magnets
Neodymium magnets can take the form of rings, disks, balls or rectangles, and much less often in other forms. Depending on the destination, one or another form is chosen. In addition, the ingredients of neodymium magnets can turn into magneto plastics with flexibility. Magnetic vinyl, used for the production of souvenirs and magnets for refrigerators, is also a magnetoplast. It is very difficult to give the formed magnet any other shape - this will require special equipment.
How to make neodymium magnets?
Most neodymium magnets available commercially are produced by sintering in special furnaces. This is a very complex and painstaking process that takes place in an inert atmosphere or in a vacuum. The basis of magnets, as already mentioned, are neodymium, iron and boron. Production proceeds in several stages:
Powdery ingredients
- Pressing powders and shaping the future magnet;
- Setting the direction of the magnetic field;
- Sintering of powdered ingredients and magnetization.
Behind the apparent simplicity lies the work of dozens of people and dozens of pieces of equipment. The task of manufacturers is not only to give the magnet a certain shape and form a magnetic field of the necessary strength. Consumers may also need more unusual properties, such as resistance to high temperatures.
How to buy neodymium magnets?
There are many varieties of sintered neodymium magnets. They differ in traction, maximum operating temperature and dimensions. Magnetic energy is a static parameter and does not change when the magnet is resized, as it might seem at first glance. The thing is that the adhesion strength is highly dependent on the following factors:
- Magnetic properties of metals;
- The cleanliness and curvature of the metal surface;
- The area of the working side of the magnet;
- Dimensions of the magnet;
- The presence of a magnet in the metal body (allows you to form a narrower directivity of the magnetic field);
Thus, the larger the magnet and the larger its working surface area, the stronger it will be attracted to the metal surface. If the surface of the metal is streaked with bumps and covered with rust, the adhesion will drop. In this case, the magnetic energy will remain the same. This parameter is indicated by the number in the magnet brand
Original article is translated from: Неодимовый магнит купить в Украине — supermagnit.com.ua
