Introduction of Neodymium magnets
A Neodymium magnet also known as Neo magnet is a type of rare earth magnet. A rare earth magnet is a strong permanent magnet made of alloys of rare earth elements. Neodymium magnets (Nd2Fe14B) are the most widely used ones and are made from an alloy of Neodymium (Nd), Iron (Fe) and Boron (B).
Although classified as a rare earth element Neodymium is not so rare and is abundantly available in the earth’s crust. It has a tetragonal crystalline structure with higher magnetic energy storing capacity than other commercial rare earth magnets like samarium cobalt.
History and Production
The compound Nd2Fe14B was discovered in 1982 by General Motors Corporation and Sumitomo special Metals in an attempt to lessen the cost of the then used commercial SmCo permanent magnets. It is manufactured mainly by two processes – By rapid solidification or by the sintered magnet process.
The sintered variety of Neodymium magnets is vulnerable to corrosion; however, this problem can be addressed by applying a layer of protective coating over the magnet. At present some of the major producers of sintered Neodymium magnets are China and Japan accounting for around 45,000 to 55,000 tons of the magnet each year.
When compared to other permanent magnets on the basis of their magnetic properties Neodymium magnets have a higher remanence (measure of the strength of the magnetic field) and coercivity (material’s resistance to becoming demagnetized) but have a lower curie Temperature (the temperature at which the magnet loses its magnetic properties).
Applications and Hazards
Neodymium magnets have a huge application in the electronic industry where strong permanent magnets are required and their greater strength allows the use of lighter and smaller magnets.
They find their application in tools like head actuators for computer hard disks, magnetic resonance imaging, permanent magnet motors like servo motors, synchronous motors, spindle motors, stepper motors etc. The greater magnetic strength of this variety of magnets has also made possible their use in areas where they were not used before, for example in magnetic jewelry clasps etc.
Despite these numerous applications there are certain hazards associated with the Neodymium magnets caused due to the greater force exerted by the rare earth magnets.
A human body part pinched between two permanent magnets of this variety longer than a few centimeters can be seriously injured with some cases resulting in broken bones. Also the strong magnetic data may be hazardous to electronic devices as it may erase magnetic data in devices such as floppy disks and credit cards.
However careful use of these magnets will result in myriad applications and these most certainly are the way of the future.