Rare earth magnets have evolved from loadstones and steels to modern alloys like samarium-cobalt and neodymium-iron-boron. They are made through processes like compressing alloy flakes or sintering powder under high heat. Rare earth elements make strong magnets through quantum effects that align electron spins into a magnetized crystal structure with high magnetic properties. These magnets find applications in technologies like MRI machines, sensors, motors, and audio devices.

1. Rare Earth Magnets

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

3. 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)

6. 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)