Tdk Corporation

Fumitaka Baba

Makoto Iwasaki

Satoshi Tanaka

Chikara Ishizaka

Takeshi Masuda

Hideki Nakamura

Hideki Sasaki

Yoshinori Fujikawa

Tetsuya Hidaka

Yasushi Enokido

Taku Murase

Taeko Tsubokura

Jun Hagiwara

Satoshi Koga

Takuma Hayakawa

Takahide Kurahashi

Seiichi Endo

Makoto Nakane

Kenya Takagawa

Naoto Tsukamoto

Akira Kakinuma

Eiichiro Fukuchi

Ayato Kakoki

Ryota Kunieda

Hitoshi Maro

Keiichi Morimoto

An R-T-B based sintered magnet includes 'R', 'T', and &#x201c;B&#x201d;. &#x201c;R&#x201d; represents a rare earth element including at least Tb. &#x201c;T&#x201d; represents a metal element except rare earth elements including at least Fe, Cu, Mn, Al, and Co. &#x201c;B&#x201d; represents boron or boron and carbon. With respect to 100 mass % of a total mass of the R-T-B based sintered magnet, a content of &#x201c;R&#x201d; is 28.0 to 32.0 mass %, a content of Cu is 0.04 to 0.50 mass %, a content of Mn is 0.02 to 0.10 mass %, a content of Al is 0.15 to 0.30 mass %, a content of Co is 0.50 to 3.0 mass %, and a content of &#x201c;B&#x201d; is 0.85 to 1.0 mass %. Tb2/Tb1 is 0.40 to less than 1.0, where Tb1 and Tb2 (mass %) denote a content of Tb at a surface portion and at a core portion, respectively.

R-T-B based sintered magnet

A rare earth magnet capable of reducing an eddy current loss by virtue of a low-cost, simple configuration, when mounted in a motor, is to be provided. The rare earth magnet can include a magnet body that includes a rare earth element and iron; and a resistive layer formed on at least one surface of the magnet body, the resistive layer comprising a rare earth element, iron, and oxygen and having an average volume resistivity of 10&#x3a9;cm or more and a thickness of from 3 to 25 &#x3bc;m.

Rare earth magnet and motor

A motor includes a magnet and a coil. &#x3b1;2=[{(Br2&#x2212;Br1)/Br1}/(T2&#x2212;T1)]&#xd7;100&#x2265;&#x2212;0.10 and &#x3b1;3=[{(Br3&#x2212;Br1)/Br1}/(T3&#x2212;T1)]&#xd7;100&#x2264;&#x2212;0.12 are satisfied. In the magnet, Br1 (mT) is a residual magnetic flux density at T1 (&#xb0; C.), Br2 (mT) is a residual magnetic flux density at T2 (&#xb0; C.), and Br3 (mT) is a residual magnetic flux density at T3 (&#xb0; C.), and &#x3b1;2 (%/&#xb0; C.) is a temperature coefficient at a target temperature of T2 (&#xb0; C.) with respect to a reference temperature of T1 (&#xb0; C.), and &#x3b1;3 (%/&#xb0; C.) is a temperature coefficient at a target temperature of T3 (&#xb0; C.) with respect to a reference temperature of T1 (&#xb0; C.) in conditions of T1=23, T2=60, and T3=180.

Motor

The present invention provides a sintered magnet having superior residual magnetic flux density and coercive force. The sintered magnet of the present invention comprises a group of R-T-B based rare earth magnet crystal particleshaving a coreand a shellcovering the core, the mass ratio of a heavy rare earth element in the shellis higher than the mass ratio of a heavy rare earth element in the core, and the thickest part of the shellin the crystal particlesfaces a grain boundary triple junction. A lattice defectis formed between the coreand the shell

Sintered magnet, motor, automobile, and method for producing sintered magnet

Provided is a rare earth sintered magnetcomprising a group of main phase grainseach composed of an R-T-B-based rare earth magnet comprising a coreand a shellcovering the core, wherein a thickness of the shellis 500 nm or less, R includes a light rare earth element and a heavy rare earth element, and a Zr compoundis present in a grain boundary phaseof the group of main phase grainsand/or the shell. Also provided are a motor comprising the rare earth sintered magnetand an automobile comprising the motor.

Rare earth sintered magnet, method for producing the same, motor, and automobile

In the rare earth sintered magnet, the ratio of R2 to the sum of R1 and R2 that are contained in crystal grain boundaries surrounding the crystal grains in the rare earth sintered magnet body is higher than the ratio of R2 to the sum of R1 and R2 in the crystal grains, and the concentration of R2 increases from the central portion of the rare earth sintered magnet body toward the surface of the rare earth sintered magnet body. In addition, the degree of unevenness in residual magnetic flux density on the surface of the rare earth sintered magnet body is smaller than 3.0%.

Rare earth sintered magnet and motor

A rare earth sintered magnetincluding a magnet body that includes a rare earth compound, and a protective layer on the magnet body, having a first layer and a second layer in that order from the magnet body side, wherein the surface portion of the magnet body has a higher heavy rare earth element content than the interior of the magnet body that is surrounded by the surface portion, the first layer includes a rare earth oxide, the mass ratio of the heavy rare earth element being 1 or greater with respect to the light rare earth element, and the second layer includes an oxide containing iron and/or boron which is different from the rare earth oxide, the second layer having a lower rare earth oxide content than the first layer.

Rare earth sintered magnet, method for producing same, motor and automobile

The process for producing a magnet according to the invention is characterized by comprising a first step in which a heavy rare earth compound containing Dy or Tb as a heavy rare earth element is adhered onto a sintered compact of a rare earth magnet and a second step in which the heavy rare earth compound-adhered sintered compact is subjected to heat treatment, wherein the heavy rare earth compound is a Dy or Tb iron compound.

Process for producing magnet

There is provided a rare earth magnet with excellent Br and HcJ values. The rare earth magnet according to a preferred embodiment of the invention is characterized by being composed mainly of R (where R is at least one element selected from among rare earth elements including Y), B, Al, Cu, Zr, Co, O, C and Fe, wherein the content of each element is R: 25-34 wt %, B: 0.85-0.98 wt %, Al: 0.03-0.3 wt %, Cu: 0.01-0.15 wt %, Zr: 0.03-0.25 wt %, Co: &#x2266;3 wt % (but not 0 wt %), O: &#x2266;0.2 wt %, C: 0.03-0.15 wt % and Fe: remainder.

Rare earth magnet

A method for producing a rare earth sintered magnet uses granules having an excellent fluidity to improve the dimensional accuracy and production of a compact formed of the granules without significant property losses. The granules are formed by adding an organic liquid to primary alloy particles having a predetermined composition to produce granules having the primary alloy particles adhered together by the organic liquid. Preferably, from 1.5 to 15.0% by weight of the organic liquid is added to the primary alloy particles.

Method for producing raw material powder for rare earth sintered magnet, method for producing rare earth sintered magnet, granule and sintered body

The present invention provides a Mn&#x2014;Zn ferrite which is low in the loss in the frequency range between a few 10 kHz and a few 100 kHz and high in the saturation magnetic flux density in the vicinity of 100&#xb0; C. The present invention comprising the steps of compacting a powder having a specific surface area (based on the BET method) of 2.0 to 5.0 m/g and a 50% particle size of 0.7 to 2.0 &#x3bc;m into a compacted body having a predetermined shape and obtaining a sintered body by sintering the compacted body. It is preferable that a Mn&#x2014;Zn ferrite comprises, as main constituents, 54 to 57 mol % of FeO, 5 to 10 mol % of ZnO, 4 mol % or less (not inclusive of 0%) of NiO, and the balance substantially being MnO.

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Tokyo, Japan

Fumitaka Baba