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r-t-b series sintered magnet

A technology of R-T-B and sintered magnets, applied in the direction of magnetic objects, magnetic materials, inorganic materials, etc., can solve the problem of low corrosion resistance, achieve excellent corrosion resistance, and the effect of magnetic properties will not be reduced

Active Publication Date: 2019-03-12
TDK CORPARATION
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, it is known that R-T-B based sintered magnets have low corrosion resistance because they contain rare earth elements as main components.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0061] The main phase alloy with the composition of 14.4at%Nd-7.2at%B-76.7at%Fe-1.0at%Co-0.5at%Cu and the composition of 32at%Nd-68at%Fe were produced by the strip continuous casting method. Composition of grain boundary alloy 1 and grain boundary alloy 2 with a composition of 11.3 at% Y-88.7 at% Fe.

[0062] Hydrogen adsorption was performed on each of the obtained alloys at room temperature. Next, dehydrogenation treatment was performed at 600° C. for 1 hour in an inert gas atmosphere. At this time, as for the atmosphere during the dehydrogenation treatment, the main phase alloy and the grain boundary alloy 1 were performed in an Ar gas atmosphere, and the grain boundary alloy 2 was performed in an atmosphere with a nitrogen gas concentration of 1150 ppm.

[0063] 0.10 wt% of oleic acid amide was added as a pulverization aid to each of the obtained coarse pulverized powders, and they were mixed for 60 minutes in a nitrogen atmosphere using a Nauta mixer. Next, using a jet ...

Embodiment 2～ Embodiment 7， comparative example 3～ comparative example 5

[0090] It was produced in the same manner as in Example 1, except that the composition of the main phase alloy and grain boundary alloy 1 was the same as in Example 1, and that the composition of grain boundary alloy 2 was shown in Table 1. sintered magnets. Calculation of Y / R, O / R, and N / R, the area ratio of the R-N-O-C concentrated part occupying the grain boundary, evaluation of magnetic properties, and evaluation of corrosion resistance were carried out in the same manner as in Example 1. The production conditions are comprehensively shown in Table 1, and the evaluation results are shown in Table 2 comprehensively.

[0091] When comparing Example 1 to Example 7 and Comparative Example 3 to Comparative Example 5, the corrosion resistance shows a high value in the range of Y / R of 0.65 or more and 1.00 or less. Moreover, corrosion resistance shows a higher value in the range which Y / R is 0.77-1.00. If Y / R is less than 0.65, the passivation layer combining Y and N is not suf...

Embodiment 8～ Embodiment 13

[0097]

[0098] Except that the compositions of the main phase alloy and the grain boundary alloy 1 were the same as in Example 1, and the grain boundary alloy 2 was prepared in a manner shown in Table 3, and the oxygen concentration at the time of pulverization was changed to Other than that shown in Table 3, a sintered magnet was produced in the same manner as in Example 1. Calculation of Y / R, O / R, N / R, area ratio of the R-N-O-C concentrated part in the grain boundary, evaluation of magnetic properties and evaluation of corrosion resistance were carried out in the same manner as in Example 1, and the production conditions are comprehensively shown in Table 3, and the evaluation results are shown in Table 4 comprehensively.

[0099] When comparing Examples 8 to 13, Comparative Example 6, and Comparative Example 7, the corrosion resistance shows a high value in the range where O / R exceeds 0 and is 0.20 or less, and when O / R exceeds 0 and is 0.16 Below, higher corrosion resi...

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Abstract

An R-T-B based sintered magnet includes R2T14B crystal grains. A grain boundary formed by the two or more adjacent R2T14B crystal grains includes an R-N-O-C concentrated part having higher concentrations of 'R', N, O, and C than those in the R2T14B crystal grains. 'R' of the R-N-O-C concentrated part includes Y. A ratio of Y atom to 'R' atom in the R-N-O-C concentrated part is 0.65 or more and 1.00 or less. A ratio of O atom to 'R' atom in the R-N-O-C concentrated part is more than 0 and 0.20 or less. A ratio of N atom to 'R' atom in the R-N-O-C concentrated part is 0.03 or more and 0.15 or less.

Description

technical field [0001] The present invention relates to an R-T-B system sintered magnet, in particular to a magnet with excellent corrosion resistance. Background technique [0002] known as tetragonal R 2 T 14 The R-T-B system sintered magnet with B compound as the main phase (R is a rare earth element, T is one or more transition metal elements with Fe as an essential element, and B is boron) has excellent magnetic properties. It was developed in 1982. It is a representative high-performance permanent magnet since the invention (Patent Document 1). [0003] In particular, the R-T-B system sintered magnet composed of Nd, Pr, Dy, Ho, and Tb, which is composed of rare earth elements R, has a large anisotropic magnetic field Ha, and is widely used as a permanent magnet material. Among them, Nd where the rare earth element R is set as Nd 2 Fe 14 The B sintered magnet has a good balance of saturation magnetization Is, Curie temperature Tc, and anisotropic magnetic field Ha,...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01F1/057H01F1/08
CPCH01F1/0571H01F1/0577
Inventor 多田笃司
Owner TDK CORPARATION