Shin-etsu Chemical Co., Ltd.

Nissin Chemical Industry Co., Ltd.

Tetsuya Ohashi

Koichi Hirota

Hajime Nakamura

Tetsuya Kume

Hiroto Sugahara

Kazuaki Sakaki

Hirochika Naganawa

Kojiro Shimojo

Masahiko Ikka

Mikio Yoshida

Kazuya Fukui

Hiroki Iida

Michihiro Oida

Akira Fujimoto

Taiga Asai

Akira Yamada

A rare earth sintered magnet is manufactured by preparing a R-T-X sintered body having a major phase of RTX composition wherein Ris a rare earth element(s) and essentially contains Pr and/or Nd, T is Fe, Co, Al, Ga, and/or Cu, and essentially contains Fe, and X is boron and/or carbon, forming an alloy powder containing 5≤R≤60, 5≤M≤70, and 20<B≤70, in at %, wherein Ris a rare earth element(s) and essentially contains Dy and/or Tb, M is Fe, Cu, Al, Co, Mn, Ni, Sn, and/or Si, and B is boron, disposing the alloy powder on the sintered body, and heat treating the alloy-covered sintered body.

Method for manufacturing rare earth sintered magnet

A rare earth sintered magnet is produced by depositing a coating of rare earth-containing particles on the surface of a rare earth magnet body, and heat treating the magnet body for causing absorption and diffusion of rare earth element in the magnet body. The depositing step utilizes a particle impingement phenomenon.

Method for producing rare earth sintered magnet

Provided is a rare earth sintered magnet in which a multi-layer main phase particle having multiple layers including a layer 1 having Rconcentration, represented by at %, higher than that of a center of the particle, a layer 2 which is formed on the outside of the layer 1 and has Rconcentration lower than that of the layer 1, and a layer 3 which is formed on the outside of the layer 2 and has Rconcentration higher than that of the layer 2 is present at least in a portion in the vicinity of a surface of the main phase particle within at least 500 &#x3bc;m from a surface of the sintered magnet body.

Rare earth sintered magnet

R&#x2014;Fe&#x2014;B sintered magnet has a main phase containing R(Fe,(Co))B intermetallic compound and a grain boundary phase. The inter-particle grain boundary includes an expanded width part that is surrounded by a narrow width part at which the inter-particle width is 10 nm or less and that has a structure distended in the inter-particle width direction as compared with the grain boundary width of the narrow width part; the inter-particle width at the expanded width part is at least 30 nm; Fe/R ratio in the expanded width part is 0.01-2.5; the main phase includes, in the surface part thereof, an HR-rich phase represented by (R',HR)(Fe,(Co))B (R&#x2032; represents rare-earth elements excluding Dy, Tb, and Ho, and that essentially include Nd; and HR represents Dy, Tb, and Ho); the contained amount of HR in the HR-rich phase is higher than that in the central part of the main phase.

R&#x2014;Fe&#x2014;B sintered magnet and production method therefor

An R&#x2014;Fe&#x2014;B base sintered magnet is provided comprising a main phase containing an HR rich phase of (R',HR)(Fe,(Co))B wherein R&#x2032; is an element selected from yttrium and rare earth elements exclusive of Dy, Tb and Ho, and essentially contains Nd, and HR is an element selected from Dy, Tb and Ho, and a grain boundary phase containing a (R&#x2032;,HR)&#x2014;Fe(Co)-Mphase in the form of an amorphous phase and/or nanocrystalline phase, the (R&#x2032;,HR)&#x2014;Fe(Co)-Mphase consisting essentially of 25-35 at % of (R&#x2032;,HR), 2-8 at % of Mwhich is at least one element selected from Si, Al, Mn, Ni, Cu, Zn, Ga, Ge, Pd, Ag, Cd, In, Sn, Sb, Pt, Au, Hg, Pb, and Bi, up to 8 at % of Co, and the balance of Fe. The HR rich phase has a higher HR content than the HR content of the main phase at its center. The magnet produces a high coercivity despite a low content of Dy, Tb and Ho.

R-Fe-B sintered magnet

An R&#x2014;Fe&#x2014;B base sintered magnet is prepared through the steps of providing an alloy fine powder having a predetermined composition, compression shaping the alloy fine powder in an applied magnetic field into a compact, sintering the compact at a temperature of 900-1,250&#xb0; C. into a sintered body, cooling the sintered body to 400&#xb0; C. or below, high-temperature heat treatment including placing a metal, compound or intermetallic compound containing HR which is Dy, Tb and/or Ho, on the surface of the sintered body, heating at a temperature from more than 950&#xb0; C. to 1,100&#xb0; C., for causing grain boundary diffusion of HR into the sintered body, and cooling to 400&#xb0; C. or below, and low-temperature heat treatment including heating at a temperature of 400-600&#xb0; C. and cooling to 300&#xb0; C. or below. The sintered magnet produces a high coercivity despite a low content of Dy, Tb and Ho.

Method for preparing R&#x2014;Fe&#x2014;B sintered magnet

An R&#x2014;Fe&#x2014;B base sintered magnet is provided comprising a main phase containing an HR rich phase of (R', HR)(Fe,(Co))B wherein R&#x2032; is an element selected from yttrium and rare earth elements exclusive of Dy, Tb and Ho, and essentially contains Nd, and HR is an element selected from Dy, Tb and Ho, and a grain boundary phase containing a (R&#x2032;, HR)&#x2014;Fe(Co)-Mphase in the form of an amorphous phase and/or nanocrystalline phase, the (R&#x2032;, HR)&#x2014;Fe(Co)-Mphase consisting essentially of 25-35 at % of (R&#x2032;, HR), 2-8 at % of Mwhich is at least one element selected from Si, Al, Mn, Ni, Cu, Zn, Ga, Ge, Pd, Ag, Cd, In, Sn, Sb, Pt, Au, Hg, Pb, and Bi, up to 8 at % of Co, and the balance of Fe. The HR rich phase has a higher HR content than the HR content of the main phase at its center. The magnet produces a high coercivity despite a low content of Dy, Tb and Ho.

A rare earth metal extractant in the form of a dialkyl diglycol amic acid is synthesized by reacting diglycolic anhydride with a dialkylamine in an aprotic polar solvent, with a molar ratio of dialkylamine to diglycolic anhydride being at least 1.0, and removing the aprotic polar solvent.

Synthesis of rare earth metal extractant

A rare earth metal extractant in the form of a dialkyl diglycol amic acid is synthesized by reacting diglycolic anhydride with a dialkylamine in a synthesis medium. A molar ratio (B/A) of dialkylamine (B) to diglycolic anhydride (A) is at least 1.0. A non-polar or low-polar solvent in which the dialkyl diglycol amic acid is dissolvable is used as the synthesis medium.

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Echizen, Japan

Tetsuya Ohashi