Rare Earth Magnets by Christopher Rust Neodymium-Iron-Boron Magnets Nd 2 Fe 14 B

History –Loadstones (Fe 3 O 4 ) –Steels –Alnicos (Al, Ni, Co, and Fe) –Ferrites –Rare-Earth Samarium-Cobalt Neodymium-Iron-Boron

What Makes a Magnet Quantum Level Spinning and Orbiting Electrons Hysteresis Loop Crystal Structure –Tetragonal Symmetry Rare-Earth Element –High Curie Temperature –High Magnetization –High Coercivity –High Remanence

Processing Rare-Earth Magnets Classifications –Bonded Compressing a mixture of NdFeB alloy flakes with a resin bonding agent –Sintered Powdered alloy (3-5 micrometers) is aligned in an electromagnetic coil, pressed into shape, and then sintered at 1000 degrees Celsius High Corrosion Factor –Types of coatings Aluminum ion deposition Nickel plating Epoxy-resin Painting Electrolytic Deposition

Applications of Rare-Earth Magnets Aerospace –Frictionless Couplings –Auto Compass Automotive Medical –Magnetic Resonance Imaging –Dentures –Wound Closures –Optical Implants Domestic –Head sets –Electric Clocks –Hearing Aids Electronic Instrumentation –Sensors –Servo Motors (robotics)

References Buschow, K.H.J., Feijen, F.H. and de Kort, Kees. Journal of Magnetism and Magnetic Materials. “Rare earth permanent magnets.” North-Holland: Elsevier Science Publishers, Callister, William D. Materials Science and Engineering an Introduction. 6 th ed. New York: John Wiley & Sons, Inc Cassar, Victor. Australian Magnet Technology Pty Ltd Coey, J.M.D. Journal of Magnetism and Magnetic Materials. “Rare-earth magnets.” North- Holland: Elsevier Science Ltd., Croat, J.J. and Herbst, J.F. Journal of Magnetism and Magnetic Materials. “Neodymium- iron-boron permanent magnets.” North-Holland: Elsevier Science Publishers,