Rare earth magnets refer to powerful permanent magnets composed of rare earth element alloys. Among permanent magnets, rare earth magnets can generate the largest magnetic field, which is much larger than that of AlNiCo magnets or ferrite magnets. Rare earth magnets can generally generate a magnetic field exceeding 1.4 Tesla, while ferrite magnets or ceramic magnets are only about 0.5 to 1 Tesla. In this article, let’s take a closer look at the rare earth magnet types and uses.
Rare Earth Magnet Types and Uses
There are two most common types of rare earth magnets: neodymium magnets (also called NdFeB magnets) and SmCo magnets. The two types of magnets contain the rare earth elements neodymium and samarium respectively. Rare earth magnets are very fragile and susceptible to corrosion. Therefore, the outer layer is generally plated with other metals to protect the rare earth magnet itself.
Neodymium magnets were invented in the 1980s. They are the strongest and most accessible rare earth magnets. It is composed of an alloy of neodymium, iron, and boron: (Nd2Fe14B), so it is also called neodymium iron boron magnet.
The magnetic field strength of neodymium magnets is the strongest among permanent magnets. Compared with samarium cobalt magnets, neodymium magnets have higher coercivity, but have a lower Curie temperature and are easier to be oxidized. In order to avoid corrosion, the neodymium magnet needs to be protected during use, such as electroplating with gold, nickel, zinc, and tin and spraying epoxy on the surface.
Uses of Neodymium Magnets
Neodymium magnets can be used on many occasions that require large magnetic fields or smaller magnets, such as motors in battery-powered tools, hard drives, and jewelry buckles.
In the early days, due to the high cost of raw materials and patent authorization, neodymium magnets were very expensive and could only be used in some applications that required high magnetic field strength. But since 1990, the cost of neodymium magnets has continued to decrease, so some magnetic toys also use neodymium magnets.
SmCo magnet is made of samarium, cobalt, and other metal rare earth materials. It is the first rare earth magnet discovered.
SmCo magnets have two composition ratios, namely (samarium atom: cobalt atom) 1:5 and 2:17. SmCo magnets have a high magnetic energy product, a very low-temperature coefficient, and the maximum operating temperature can reach 350°C. When the working temperature is above 180℃, their maximum magnetic energy product (BHmax), coercivity, temperature stability, and chemical stability all exceed NdFeB permanent magnets. The maximum energy product (BHmax) of samarium cobalt magnets ranges from 16 MGOe to 32 MGOe, and its theoretical limit is 34 MGOe. Moreover, they have strong corrosion and oxidation resistance.
Uses of SmCo Magnets
Because the prices of the samarium cobalt magnets are high, their applications are less. Due to the high Curie temperature of samarium cobalt magnets, it can be applied to occasions that require a large magnetic field at high temperatures.
Thank you for reading our article and we hope it can help you to have a better understanding of the rare earth magnet types and uses. If you want to learn more about rare earth magnets, we would like to advise you to visit Stanford Magnets for more information.
As a leading magnet supplier across the world, Stanford Magnets has been involved in R&D, manufacturing, and sales of magnets since the 1990s. It provides customers with high-quality permanent magnets like SmCo magnets,neodymium magnets, AlNiCo magnets, and ferrite magnets (ceramic magnets) at a very competitive price.