Rare Earth Magnets

1
Rare Earth Magnets
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History

• Loadstones (Fe3O4)
• Steels
• Alnicos (Al, Ni, Co, and Fe)
• Ferrites
• Rare-Earth
• Samarium-Cobalt
• Neodymium-Iron-Boron

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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

4
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

5
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)