hardmagneetteihin

Hardmagneetteihin refers to hard magnetic materials, commonly known in English as permanent magnets. In magnetism, these materials are distinguished by high coercivity and the ability to retain magnetic alignment after removal of an external magnetic field, enabling a persistent magnetic field without ongoing power input.

The most common hard magnetic materials are rare-earth magnets such as neodymium-iron-boron (NdFeB) and samarium-cobalt (SmCo), ferrites (hard ferrites), and, historically, Alnico alloys. They are chosen based on energy product, temperature stability, corrosion resistance, and cost. NdFeB magnets offer high energy density but are sensitive to high temperatures and corrosion unless coated. SmCo magnets have excellent temperature stability and corrosion resistance but are more expensive. Ferrites are inexpensive and corrosion resistant but have lower energy density.

Applications include electric motors and generators, wind turbines, hard disk drive magnets, loudspeakers, magnetic sensors, medical devices, and various consumer electronics. Magnetic design must consider Curie temperature, coercivity, remanence, and temperature coefficients to maintain performance in operating conditions. Engineers balance material composition, magnet geometry, and protective coatings to meet mechanical and thermal demands in real-world devices.

Development of hard magnets has progressed from Alnico in the mid-20th century to rare-earth magnets in the 1980s and beyond. The term hardmagneetteihin appears in Finnish-language texts as a category for these materials, and discussions often address supply chains, material science challenges, and the environmental impact of rare-earth mining.

See also: magnetism, permanent magnet, coercivity, energy product, NdFeB, SmCo.