If we pay attention, it will be very easy to found many rare earth magnets in our daily life. It is a very common feature in household appliances. These magnets are permanent magnets, and it sounds like fancy for many people. But do you have any idea about what it is different from other type magnets? So let s talk about the history of rare earth magnet.
History of Rare Earth Magnets
In last century, Rare earth magnets were developed by the scientists who at the United States Air Force Materials Laboratory. They found an alloy had the largest magnetic anisotropy. And they name the alloy “rare earth magnets”. Even the name insinuates that these magnets are sparse and hard to find. But in fact, they’re actually as abundant as iron or Gold. However, the main source is all come from China. They have good quality and big quantity material. And the point is most of them are high classify and cannot found in other countries.
How to produce Rare Earth Magnets
Once the raw material is sent to the manufacturer, it will be ground into powder. And then it will be mixed with other material to produce the magnet. And the different content of the raw material and other material, it will take the grade and the magnetic properties different. The powder will be pressed into a form (in normal, the form is the rectangle, Square or Circular) and then aligned using a big electromagnet. After the particles are aligned, the material is sintered to lock everything in place. In future, the material is a further process and cut down into smaller pieces. Once the final shape has been confirmed, the magnets will need a protect. And about the protect, it could be coated or plated. And they can protect the magnet from corrosion. At last, the magnets will be magnetized. Likes the normal magnet we use.
How to makes the rare magnet better
As the rare magnet is produced with different powder, different alloys. So their quality and strength are different from other magnets. In this business, BHMax is used for measured the magnetic fields. For example, the ceramic magnets (it is high strength in magnets) have a BHMax of 3.5, the strongest rare earth magnets have a strength of 40. And the Ferrite Magnet will be lower.
If the temperatures are too high, the magnets will demagnetize. And we call the temperatures Tcurie value. And different material magnet has a different Tcurie temperature. In normal, the ceramic magnet is 460 degrees Celsius(860 Fahrenheit).
And rare earth magnets is closer to 750 degrees Celsius (1382 Fahrenheit). So it means that rare earth magnets stand much higher temperatures before demagnetized.
No matter ceramic or SmCo magnets, both of them are rare earth magnet, are much more able to against corrosion. And neodymium magnets are rare earth magnet too, but it is rather brittle. And about the manufacture, neodymium is very difficult to produce. In a word, rare earth magnets are not a magical product. So what we should do is know more about them.