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Difference between rare earth magnets and ceramic magnets

If you need to know the difference between rare earth magnets and ceramic magnets, in the following article you will find all the information to get out of doubts.

What magnets are rare earths?

The term rare earth includes 17 elements of the periodic table. These are the elements of the third subgroup, except actinium and lanthanides. Lanthanides also include the samarium (Sm; article No. 62) and neodymium (Nd; article No. 60) components.

Permanent magnets made of rare earths are the two metal alloys samarium-cobalt (SmCo) and neodymium-iron-boron (NdFeB). The term "rare earth magnets" therefore includes neodymium magnets and samarium-cobalt magnets.

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What is the definition of ceramic magnets?

Ceramic magnets date back to the 1950s. These are permanent hard ferrite magnets that have a hexagonal molecular lattice structure. Ceramic magnets are cheap to manufacture and also to produce in thinner cuts. They are relatively resistant to weak demagnetizing fields and still retain their magnetic properties. The special property of the hexagonal molecular lattice structure is found in iron oxide, which is alloyed with barium oxide (BaO * 6Fe2O3). In addition, the strontium oxide contained as an alloying element iron oxide (SrO * 6Fe2O3) has such a hexagonal molecular structure.

The advantage of strontium (Sr) ferrite lies in its magnetic properties, which are slightly better than barium (Ba) ferrite. Permanent magnets designed as ceramic magnets are very common because they also have good resistance to demagnetization in addition to the advantage of economical production. Another positive point of these ceramic magnets is their high corrosion resistance. With artificially produced ceramic magnets, new production possibilities arise, as this type of permanent magnet can be adapted to any desired shape.

 

What is the difference between rare earth magnets and ceramic magnets?

Both rare earth magnets and ceramic magnets are part of the large group of permanent magnets. After your magnetic material has undergone the magnetisation process during manufacture, these permanent magnets work for a long time if they are not seriously damaged. However, since rare earth magnets and ceramic magnets are made of different metal alloys, there are also differences in their strength and load-bearing capacity.

Rare earth magnets such as neodymium have the strongest magnetic properties of all permanent magnets. Both types of rare earth magnets, samarium cobalt and neodymium-iron-boron, are extracted before going through the magnetization process. An essential distinction between rare earth magnets and ceramic magnets is also their maximum energy product BHmax, which is measured in MegaGauss Oersted (MGOe). This BHmax value is 3.5 for ceramic magnets, 26 for SmCo and 40 for NdFeB.

 

Conclusion

Permanent magnets are used in many technical products and are indispensable today. The wide range of applications extends to smaller electric motors (windscreen wipers, electric window motors in cars), such as lifting magnets, electric relays, compasses and loudspeakers.

In all applications, however, it must be borne in mind that permanent magnets are sensitive to overheating. Neodymium magnets can withstand up to one tmax. (maximum temperature) of 180ºC. Ceramic magnets and SmCo magnets retain their magnetic properties up to a maximum temperature of 300ºC.

If you have technical questions or problems related to magnetism and permanent magnets, we are at your disposal with all our experience in this complex field. Do not hesitate to contact us.

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