Rare earth element magnet
a magnet and rare earth technology, applied in the field of rare earth element magnets, can solve the problems of poor magnetic characteristics and worsening magnetic characteristics, and achieve the effects of improving magnetic characteristics, high reliability, and high corrosion resistan
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example 1
[0021]Each of the steps for manufacturing the compact-molded magnet will be explained.
[0022](1) Magnetic powder is prepared as follows. In this example as rare earth element magnetic powder, used was a thin foil of NdFeB alloy, which was prepared by rapidly quenching molten mother alloy. The NdFeB mother alloy was prepared by mixing Nd with Fe—B alloy (ferro boron, FeB) and melting the mixture in an inert gas atmosphere or a reducing gas atmosphere to produce the alloy with a homogeneous composition.
[0023]If desired, the molten alloy is formed into a thin foil on a rotating single roll or twin rolls by injecting the molten alloy and rapidly quenching in the inert gas such as argon gas or reducing gas atmosphere, followed by heat-treating the foil in the inert gas or in the reducing gas. The heat treating temperature is 200 to 700° C. The heat treatment causes fine grains of Nd2Fe14B to be formed in the magnetic powder and to grow therein. The thin foil has a thickness of 10 to 100 μ...
example 2
[0072]In this example a method of manufacturing compact molding test pieces using anisotropic magnetic powder will be explained each step.
[0073](1) A example will be explained by using anisotropic magnetic powder wherein c-axis of tetragonal fine Nd2Fe14B crystals were oriented. The magnetic powder used in this Example differs from flake magnetic powder, which has magnetic anisotropy, used in Example 1. In this Example, used was magnetic powder whose particle size was 1 to 1000 μm, the powder having been subjected to hydrogenation-dehydrogenation treatment (HDDR). A coercive force of the magnetic powder was 16 kOe at room temperature. Instead of this magnetic powder, other anisotropic magnetic powders can be employed.
[0074](2) The magnetic powder prepared at the step (1) was filled in a non-magnetic mold and pre-compact-molded under a pressure of 50 MPa in a magnetic field of 1.5 T. The anisotropic magnetic powder is oriented in the magnetic field. The pre-molding in the magnetic fi...
example 3
[0088]In this example, there are shown bending strength, specific resistivity and magnetic characteristics when compositions of the SiO2 precursor solution were differently changed. As the magnetic powder, MQP-14-12 manufactured by Magnequench International Inc. was used. In the following, steps for manufacturing the magnets will be explained.
[0089](1) MQP14-12, which is rapid-quenched magnetic powder, is chemically stable magnetic powder, which is not oxidized or corroded in atmosphere. The above-magnetic power is flake powder having a thickness of 10 to 100 μm.
[0090](2) The powder of (1) was filled in a mold and molded under a pressure of 16 t / cm2 into test pieces each having a longitude of 10 mm, a width of 10 mm and a thickness of 8 mm for measuring magnetic characteristics.
[0091](3) The compact molding test pieces prepared at the step of (2) were subjected to heat treatment at a temperature higher than the temperature employed in the bond magnet, but lower than that employed in...
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