Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
  • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
  • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
  • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
  • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
  • H01F1/047—Alloys characterised by their composition
  • H01F1/053—Alloys characterised by their composition containing rare earth metals
  • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
  • H01F1/058—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IVa elements, e.g. Gd2Fe14C
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
  • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
  • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
  • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
  • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
  • H01F1/047—Alloys characterised by their composition
  • H01F1/053—Alloys characterised by their composition containing rare earth metals
  • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
  • H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
  • H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
  • H01F1/0575—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together
  • H01F1/0577—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together sintered

Definitions

• the invention relates to a permanent magnet with at least one intermetallic compound in a tetragonal crystal structure, which contains at least one rare earth (R), at least one transition metal (TM) and boron (B).
• R rare earth
• TM transition metal
• B boron
• a permanent magnet of this type is known from EP 0 101 552 B1, with Nd preferably being used as the rare earth and Fe as the transition metal.
• Nd preferably being used as the rare earth and Fe as the transition metal.
• Such a permanent magnet has good magnetic properties only if the main part of the magnet has a tetragonal crystal structure. This presupposes that the starting materials for the alloy powder contain no impurities or additives or only contain a negligible proportion. Such starting materials are very expensive in terms of the required purity, so that the permanent magnet cannot be manufactured inexpensively.
• rare earths such as Nd
• transition metals such as Fe
• the permanent magnet contains two alloys that are suitable for the formation of magnetic phases with a tetragonal crystal structure.
• the proportion of B and C is matched to one another so that processing in the presence of oxygen is facilitated.
• the oxygen can be contained in the form of rare earth oxides.
• the carbon added to the known reduction can at least partially be present as an impurity in the transition metal and contributes to the formation of a carbon-rich magnetic phase, so that the non-magnetic phase is reduced proportionately. Since, in particular, heavy rare earths are much cheaper than oxides, the permanent magnets with the two magnetic phases can be produced more cheaply than the known permanent magnets with only a single magnetic phase with a tetragonal crystal structure.
• the essence of the invention is therefore essentially to use two alloys suitable for the formation of magnetic phases for the production of a permanent magnet with different magnetic phases, but with the same crystal structure, and thereby the advantages of producing a permanent magnet from an oxygen-enriched alloy, the proportion of which when sintering is stabilized to a predetermined value with the help of carbon.
• non-magnetic phases of the composition (R) 1 Fe 4 B 4 and (R) 1 Fe 4 Ca 4 as well as oxides of the light rare earths (LSE 2 O 3 ), which are also non-magnetic, are formed .
• the proportion of rare earths (R) in the permanent magnet is preferably chosen such that (R) is the sum of R 1 and R 2 , where R 1 is at least one light rare earth (LSE) and R 2 is at least one heavy rare earth ( SSE) and / or an oxide of at least one heavy rare earth (SSE 2 O 3 ).
• the oxide of the heavy rare earth becomes metal, while the oxygen released (O 2 ) combines with the light rare earth (LSE) to form the non-magnetic LSE 2 O 3 phase, with an O 2 content of approximately in the permanent magnet 0.06 to 1.3% by weight remains.
• the proportion of the transition metal TM is chosen according to the following relationship:
• Iron and cobalt are used as transition metals, so that, for example, magnetic tetragonal phases of the following Can form composition when neodymium Nd is used as light rare earths
• Nd 2 (FeCo) 14 B 1 or Nd 2 (FeCo) 14 C 1 are examples of Nd 2 (FeCo) 14 B 1 or Nd 2 (FeCo) 14 C 1 .
• the permanent magnet can also contain additives Z 0.02 which have at least one element from the group Al, Ti, V, W, Mn, Ni, Si, Cu, Zr, Nb, Ta, Hf, Sn and Pb .
• the elements AI, Nb, MO, W, Ta have proven to be advantageous and accumulating in the border phase.
• An alloy powder for producing a permanent magnet with the two tetragonal magnetic phases is characterized in that it consists of at least one rare earth with additives and / or oxides, at least one transition metal with impurities and B and possibly additionally C, the proportion of B being about 0 , 9 to 1.2% by weight, the proportion of C approximately 0.05 to 0.15% by weight and the proportion of O2 approximately up to 1.5% by weight.
• the heavy rare earth oxides and the carbon content of the transition metals allow the formation of the two tetragonal phases with cheap starting materials. If necessary, additional carbon and oxygen can be added to obtain the specified proportions.
• the composition of the rare earths is characterized in that it contains a first portion (R 1 ) of a light rare earth LSE with approximately 28 to 34% by weight and a second portion (R 2 ) of at least one oxide of a heavy rare earth (SSE 2 O 3 ) with about 0.1 to 5 wt .-%, which is used to produce the alloy powder.
• R 1 a first portion of a light rare earth LSE with approximately 28 to 34% by weight
• R 2 a second portion of at least one oxide of a heavy rare earth (SSE 2 O 3 ) with about 0.1 to 5 wt .-%, which is used to produce the alloy powder.
• carbon steel (Fe) and / or carbon cobalt (Co) is used as the starting material.
• a method is used which is characterized in that the starting materials are melted, homogenized and ground into alloy powder, that additional oxygen (O 2 ) is added to a final concentration of about 1.5% by weight during grinding, and that the alloy powder is aligned in the magnetic field, pressed and, like conventional RE magnets, into a permanent magnet is sintered with an energy product of 20 MOe to 40 MOe.
• the master alloy from the light rare earths LSE, the oxides of the heavy rare earths SSE 2 O 3 , the carbon-containing transition metals Fe and / or Co is melted with the additives, the boron or ferroboron and any carbon added, homogenized and ground to alloy powder. Additional oxygen O 2 can be added during the grinding to a final concentration of up to about 1.5% by weight.
• the carbon content in the alloy powder is brought up to about 0.2% by weight and the powder is then processed further in air. In a die press, the alloy powder is aligned in a constant field of about 14 kOe and pressed into green compacts at a pressure of about 1 kbar. The green compacts then still had an oxygen content of up to 1.24% by weight.
• the green compacts are heated to about 1,030 ° C. in a vacuum oven and kept at this temperature for about 3 hours.
• Part of the carbon of the alloy combines with the excess oxygen and escapes in the form of CO and / or CO 2 , which is sucked off and removed with vacuum pumps.
• the subsequent sintering brings the permanent magnet to a final density of approximately 7.3 to 7.6 g / cm 3 .
• Part of the carbon escapes and achieves a reduction in the oxygen content and / or the proportion of rare earth metal oxides, while the remaining proportion of carbon forms a magnetic phase, which contributes to the excellent properties of this magnet.
• the permanent magnet has excellent mechanical and thermal stability and the oxygenation during the manufacturing process makes the processing of the alloy much easier and easier.
• the main phases of the permanent magnet are tetragonal and magnetic, while only a small proportion of non-magnetic phases are created in the magnetic structure, although no pure, expensive starting materials were used to produce the alloy and the permanent magnet.
• the alloy is homogenized. After homogenization, rapid cooling is carried out, preferably at a cooling rate of about 1,000 ° C / min. This is the only way to ensure that the tetragonal magnetic phase with C, for example Nd 2 (FeCo) 14 C 1 , is also formed.

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• Chemical & Material Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Hard Magnetic Materials (AREA)
• Powder Metallurgy (AREA)
• Manufacturing Cores, Coils, And Magnets (AREA)

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• 1989
  • 1989-08-28 DE DE3928389A patent/DE3928389A1/de active Granted
• 1990
  • 1990-08-27 JP JP2512098A patent/JPH05500134A/ja active Pending
  • 1990-08-27 EP EP90912788A patent/EP0489784B1/de not_active Expired - Lifetime
  • 1990-08-27 WO PCT/DE1990/000653 patent/WO1991003823A1/de active IP Right Grant
  • 1990-08-27 DE DE90912788T patent/DE59004054D1/de not_active Expired - Fee Related

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