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Neodymium Magnets: Major Source - Wikipedia
A neodymium magnet (also known as NdFeB, NIB, or Neo magnet), a type of rare-earth magnet, is a permanent magnet made from an alloy of neodymium, iron, and boron to form Nd2Fe14B. Neodymium magnets are more powerful than samarium cobalt (SmCo) magnets, which were the first type of rare earth magnet to be commercialized, and are currently the strongest type of permanent magnet.
The automotive industry is currently sucking-up the world’s available supply of neodymium (& other rare-earth metals) for the electric motors and batteries used in ’Hybrid’ vehicles. Plans are already in the works to open new mines to increase the supply of these RARE metals. This shortage will probably have an impact on RC usage of these magnetic materials, i.e., availability and/or cost.
Neodymium is alloyed with terbium and dysprosium (two other rare-earth metals) in order to preserve its magnetic properties at high temperatures.
Sintered Nd2Fe14B is highly liable to corrosion. One cubic centimeter will completely oxidize after exposure to air for 1 year. To prevent corrosion most of the magnets get coated. Nickel plating or two layered copper nickel plating is used as a standard method, although plating with other metals or polymer and lacquer protective coatings are also in use.
If the coating used on the rotor becomes defective & allows air to come in contact with the neodymium compounds, just say bye-bye to that rotor’s magnetic capabilities in a relatively short period of time. This info makes me wonder about the various manufacturer’s claims as to the actual composition/quality of their motor magnets.
Sintered - Full Density magnetically aligned powder is formed into dense blocks which are then heat treated (the powder is heated in a pressurized mold to just below the melting point until the molecules fuse together), cut to shape, surface treated and magnetized.
Bonded - Spin Melting creates a powder, to which a bonding agent is added, to form the magnet into the desired shape.
Some important properties used to compare permanent magnets are: remanence (Mr), which measures the strength of the magnetic field; coercivity (Hci), the material's resistance to becoming demagnetized; energy product (BHmax), the density of magnetic energy; and Curie temperature (TC), the temperature at which the material loses its magnetism. [See Attached].
A neodymium magnet (also known as NdFeB, NIB, or Neo magnet), a type of rare-earth magnet, is a permanent magnet made from an alloy of neodymium, iron, and boron to form Nd2Fe14B. Neodymium magnets are more powerful than samarium cobalt (SmCo) magnets, which were the first type of rare earth magnet to be commercialized, and are currently the strongest type of permanent magnet.
The automotive industry is currently sucking-up the world’s available supply of neodymium (& other rare-earth metals) for the electric motors and batteries used in ’Hybrid’ vehicles. Plans are already in the works to open new mines to increase the supply of these RARE metals. This shortage will probably have an impact on RC usage of these magnetic materials, i.e., availability and/or cost.
Neodymium is alloyed with terbium and dysprosium (two other rare-earth metals) in order to preserve its magnetic properties at high temperatures.
Sintered Nd2Fe14B is highly liable to corrosion. One cubic centimeter will completely oxidize after exposure to air for 1 year. To prevent corrosion most of the magnets get coated. Nickel plating or two layered copper nickel plating is used as a standard method, although plating with other metals or polymer and lacquer protective coatings are also in use.
If the coating used on the rotor becomes defective & allows air to come in contact with the neodymium compounds, just say bye-bye to that rotor’s magnetic capabilities in a relatively short period of time. This info makes me wonder about the various manufacturer’s claims as to the actual composition/quality of their motor magnets.
Sintered - Full Density magnetically aligned powder is formed into dense blocks which are then heat treated (the powder is heated in a pressurized mold to just below the melting point until the molecules fuse together), cut to shape, surface treated and magnetized.
Bonded - Spin Melting creates a powder, to which a bonding agent is added, to form the magnet into the desired shape.
Some important properties used to compare permanent magnets are: remanence (Mr), which measures the strength of the magnetic field; coercivity (Hci), the material's resistance to becoming demagnetized; energy product (BHmax), the density of magnetic energy; and Curie temperature (TC), the temperature at which the material loses its magnetism. [See Attached].
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