There are various kind of magnets, alnice, ferrite, neodymium, etc. neodymium are the strongest permanent magnet.
Today, I will do some research to detail about neodymium magnet. How I know about this kind of magnet? Recently I go watch youtube~ the video web link is http://www.youtube.com/watch?v=zOdboRYf1hM&feature=related
very interesting video to me~ I like this kind of video because can let me open my eyes bigger because there are different kind of things I never seen before. there are many commments by host and he got said that:"There are various kind of magnets, alnice, ferrite, neodymium, etc. neodymium are the strongest ones."
then, I go for wikipedia to check the neodymium magnet, it is called as Nd2Fe14B tetragonal crystalline structure. it is developed at 1982 by General Motors and Sumitomo Special Metals, neodymium magnets are the strongest type of permanent magnet made.
It is made from mixing neodymium,iron and boron to form Nd2Fe14B tetragonal crystalline structure. These magnets are widely used in such products as microphones, professional loudspeakers, in-ear headphones, and computer hard disks, where low magnet mass or volume, or strong magnetic fields are required.
Larger neodymium magnets are used in high power versus weight electric motors (for example in hybrid cars) and generators (for example aircraft and wind turbine electric generators).
Advantages:
1. neodymium magnet of a few grams can lift a thousand times its own weight.
2. These magnets are cheaper, lighter, and stronger than samarium-cobalt magnets.
3. due to this high magnetic capacity, it is heavily used in the electric motors of hybrid automobiles and in the electricity generators of commercial wind turbines.
4. Neodymium has an unusually large specific heat capacity at liquid-helium temperatures, so is useful in cryocoolers ( devices used to reach cryogenic temperatures by cycling certain gases).
Disadvantages:
1. neodymium magnets lose their magnetism at high temperatures(215 degrees F and 240 degrees F or 101.1666667 degree Celsius to 115.55556 degree Celsius ), Samarium magnets do not.
2. Neodymium melts at 1,875 degrees F (1023.8888888888889 degree Celsius). .
Example: Toyota Prius ,
"The magnetic field strength of neodymium magnets declines rapidly with temperature--and hybrid electric vehicle motors get hot during operation. By the time the magnets reach temperatures between 215 degrees F and 240 degrees F, they have lost more than half their magnetic strength, only regaining it upon cooling.
According to Oak Ridge National Laboratories, the heat sensitivity of the neodymium magnets at the heart of the Toyota Prius requires the Prius's control computer to shut down the electric motor regularly and switch to the gasoline engine, to give the magnets an opportunity to cool.
Pushing the neodymium magnets above approximately 345 degrees F (173.88888888888889 degree Celsius) raises the risk of permanently demagnetizing them--which could destroy the motor. All neodymium PMs in electric vehicle applications face similar temperature challenges."
Read more: Neodymium Temperature Characteristics | eHow.com http://www.ehow.com/list_5859111_neodymium-temperature-characteristics.html#ixzz1SttGP100
Today, I will do some research to detail about neodymium magnet. How I know about this kind of magnet? Recently I go watch youtube~ the video web link is http://www.youtube.com/watch?v=zOdboRYf1hM&feature=related
very interesting video to me~ I like this kind of video because can let me open my eyes bigger because there are different kind of things I never seen before. there are many commments by host and he got said that:"There are various kind of magnets, alnice, ferrite, neodymium, etc. neodymium are the strongest ones."
then, I go for wikipedia to check the neodymium magnet, it is called as Nd2Fe14B tetragonal crystalline structure. it is developed at 1982 by General Motors and Sumitomo Special Metals, neodymium magnets are the strongest type of permanent magnet made.
It is made from mixing neodymium,iron and boron to form Nd2Fe14B tetragonal crystalline structure. These magnets are widely used in such products as microphones, professional loudspeakers, in-ear headphones, and computer hard disks, where low magnet mass or volume, or strong magnetic fields are required.
Larger neodymium magnets are used in high power versus weight electric motors (for example in hybrid cars) and generators (for example aircraft and wind turbine electric generators).
Advantages:
1. neodymium magnet of a few grams can lift a thousand times its own weight.
2. These magnets are cheaper, lighter, and stronger than samarium-cobalt magnets.
3. due to this high magnetic capacity, it is heavily used in the electric motors of hybrid automobiles and in the electricity generators of commercial wind turbines.
4. Neodymium has an unusually large specific heat capacity at liquid-helium temperatures, so is useful in cryocoolers ( devices used to reach cryogenic temperatures by cycling certain gases).
5. The element is also used in cryostats, lasers, colored glass and industrial and scientific safety goggles
Disadvantages:
1. neodymium magnets lose their magnetism at high temperatures(215 degrees F and 240 degrees F or 101.1666667 degree Celsius to 115.55556 degree Celsius ), Samarium magnets do not.
2. Neodymium melts at 1,875 degrees F (1023.8888888888889 degree Celsius). .
Example: Toyota Prius ,
"The magnetic field strength of neodymium magnets declines rapidly with temperature--and hybrid electric vehicle motors get hot during operation. By the time the magnets reach temperatures between 215 degrees F and 240 degrees F, they have lost more than half their magnetic strength, only regaining it upon cooling.
According to Oak Ridge National Laboratories, the heat sensitivity of the neodymium magnets at the heart of the Toyota Prius requires the Prius's control computer to shut down the electric motor regularly and switch to the gasoline engine, to give the magnets an opportunity to cool.
Pushing the neodymium magnets above approximately 345 degrees F (173.88888888888889 degree Celsius) raises the risk of permanently demagnetizing them--which could destroy the motor. All neodymium PMs in electric vehicle applications face similar temperature challenges."
Read more: Neodymium Temperature Characteristics | eHow.com http://www.ehow.com/list_5859111_neodymium-temperature-characteristics.html#ixzz1SttGP100
Youtube, the video about neodymium magnet against gravity
http://www.youtube.com/watch?v=MDIPv5PD-tY&feature=relmfu
http://www.youtube.com/watch?v=MDIPv5PD-tY&feature=relmfu
(Eddy current principle)
But, some said that Neodymium magnet at future is meaningless. and solution to reduce the heat rapidly by added dysprosium (Dy).
"Another REE, dysprosium, is often added to the neodymium magnets used in motors. While this improves heat resilience, dysprosium is also expensive and exclusively supplied by China, making its future availability uncertain.
Some analysts have suggested abandoning neodymium PM-based electric motors and switching to other motor technologies, such as AC induction--which do not rely on any special materials like neodymium. The majority of AC induction motors, however, do not have the rapid acceleration and small size that are characteristic of neodymium magnet-based motors."
