Rare Earth Magnets

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)