Permanent magnets are materials that retain their magnetism over long periods without the need for an external magnetic field. Four common types of permanent magnets are Alnico, Ferrite, SmCo (Samarium Cobalt), and NdFeB (Neodymium Iron Boron). Let’s compare these magnets in terms of their composition, properties, and applications:
With continuous exploration and research, With the continuous evolution of magnet development, we have discovered a variety of permanent magnets.
Following are different types of rare earth magnets:
| Alnico (Aluminum-Nickel-Cobalt-Iron) | Ferrite (Ceramic) | SmCo (Samarium Cobalt) | NdFeB (Neodymium Iron Boron) | |
| History | Since 1930’s | Since 1950’s | Since 1960’s | Since 1980’s |
| Manufacture process | Casting, Sintering | Sintering, Injection molding | Sintering | Sintering, Injection molding |
| Advantages | High working temperature, No coating needed | Low weight, No coating needed, Cheap price | High energy High working temperature No coating needed | Super-high energy |
| Disadvantages | Easily demagnetized, Low energy | Low energy, Brittle | Expensive price, brittle | Easily oxidized, Low working temperature |
| Currie Temperature | 700-860℃ | 450℃ | 720-800℃ | 310-400℃ |
| Max. Working temperature | 525℃ | 250℃ | 350℃ | 80℃ - 200℃ |
| Density | 7.3 g/cm³ | 4.8 g/cm³ | 8.4 g/cm³ | 7.5 g/cm³ |
| Compositions | Alnico magnets are made primarily from aluminum (Al), nickel (Ni), cobalt (Co), and iron (Fe), along with small amounts of other elements like copper and titanium. | Ferrite magnets are composed of iron oxide (Fe2O3) and strontium or barium carbonate (Sr/BaCO3) | SmCo magnets are made of samarium (Sm) and cobalt (Co), with traces of other elements like iron and copper. | NdFeB magnets consist of neodymium (Nd), iron (Fe), and boron (B), along with small amounts of other elements like dysprosium and terbium for enhanced performance. |
