Tdk Corporation

Fuji Jukogyo Kabushiki Kaisha

Kabushiki Kaisha Toshiba

Hitoshi Taguchi

Yoshihiko Minachi

Fumihiko Hirata

Taku Takeishi

Kiyoyuki Masuzawa

Kazumasa Iida

Teruo Mori

Junnichi Nagaoka

Keisuke Ishii

Yoshitaka Murakawa

Yuichi Sugawara

Jo Sato

Mitsuaki Sasaki

Naoharu Tanigawa

Takeshi Kitahata

Yosuke Nakazawa

Kiyohide Sumi

Manabu Sudo

Kenichiro Suwa

Miyuki Kawakami

Kikoyuki Masuzawa

Provided is a ferrite sintered magnet including a ferrite phase having a magnetoplumbite-type crystal structure. x, y, and m satisfy the following Equations (1), (2), and (3) when composition of the ferrite sintered magnet is represented by RAFeCo, where R denotes at least one kind of element selected from rare earth elements including Y and A denotes Ca or Ca and elements including at least one kind selected from Sr or Ba. The content of B in the ferrite sintered magnet is from 0.1% to 0.6% by mass in terms of BO.0.2≤≤0.8  (1)0.1≤≤0.65  (2)3≤≤14  (3)

Ferrite sintered magnet, ferrite particles, bonded magnet, motor, and generator

Provided is a ferrite sintered magnet including a ferrite phase having a magnetoplumbite-type crystal structure. x, y, and m satisfy the following Equations (1), (2), and (3) when composition of the ferrite sintered magnet is represented by RAFeCo, where R denotes at least one kind of element selected from rare earth elements including Y and A denotes Ca or Ca and elements including at least one kind selected from Sr or Ba. The content of B in the ferrite sintered magnet is from 0.1% to 0.6% by mass in terms of BO.0.2&#x2264;&#x2264;0.8&#x2003;&#x2003;(1)0.1&#x2264;&#x2264;0.65&#x2003;&#x2003;(2)3&#x2264;&#x3c;14&#x2003;&#x2003;(3)

This ferrite magnet has a magnetoplumbite structure and is characterized in that, when representing the composition ratios of the total of each metal element A, R, Fe and Me with expression (1) AR(FeMe), the Fecontent (m) in the ferrite magnet is greater than 0.1 mass % and less than 5.4 mass % (in expression (1), A is at least one element selected from Sr, Ba, Ca and Pb; R is at least one element selected from the rare-earth elements (including Y) and Bi, and includes at least La, and Me is Co, or Co and Zn). The invention makes it possible to achieve a ferrite magnet with increased Br.

Ferrite magnet

This ferrite magnet has a ferrite phase having a magnetoplumbite structure, and an orthoferrite phase, and is characterized in that the composition ratios of the total of each metal element A, R, Fe and Me is represented by expression (1) AR(FeMe), (in expression (1), A is at least one element selected from Sr, Ba, Ca and Pb; R is at least one element selected from the rare-earth elements (including Y) and Bi, and includes at least La, and Me is Co, or Co and Zn) and in that the content (m) of the orthoferrite phase is 0&#x3c;m&#x3c;28.0 in mol %. The invention makes it possible to achieve a ferrite magnet with increased Br.

A sintered ferrite magnet comprises a main phase of an M type Sr ferrite having a hexagonal crystal structure. An amount of Zn is 0.05 to 1.35 mass % in terms of ZnO and M/Mis 0.43 or less when an amount of a rare-earth element (R) is Min terms of mol and the amount of Zn is Min terms of mol.

Sintered ferrite magnet and motor provided therewith

A sintered ferrite magnet comprises a main phase of an M type Sr ferrite having a hexagonal crystal structure. An amount of Zn is 0.05 to 1.35 mass % in terms of ZnO, the sintered ferrite magnet does not substantially include a rare-earth element (R), and the following Formula (1) is satisfied, where a total amount of Sr, Ba and Ca is M3 in terms of mol, a total amount of Fe, Co, Mn, Zn, Cr and Al is M4 in terms of mol, and an amount of Si is M5 in terms of mol.0.5&#x2266;{3&#x2212;(4/12)}/5&#x2266;4.8&#x2003;&#x2003;(1).

Provided is a method for producing Sr ferrite particles for sintered magnets, the method includes: a mixing step of mixing an iron compound, a strontium compound, and an alkali metal compound which includes at least one of K and Na as a constituent element and which does not include Cl and S as the constituent element to prepare a mixture; and a calcining step of firing the mixture at 850&#xb0; C. to 1100&#xb0; C. to obtain Sr ferrite particles in which an average particle size of primary particles is 0.2 to 1.0 &#x3bc;m. In the mixing step, the alkali metal compound is mixed in such a manner that a total amount of K and Na becomes 0.03 to 1.05% by mass in terms of KO and NaO with respect to a total amount of a powder of the iron compound and a powder of the strontium compound.

Method for manufacturing Sr ferrite particle for sintered magnet, method for using Sr ferrite particle, Sr ferrite sintered magnet and method for manufacturing same, and motor and generator

Provided is a sintered ferrite magnetthat comprises Sr ferrite having a hexagonal crystal structure, wherein the total amount of Na and K is 0.004 to 0.31% by mass in terms of NaO and KO, an amount of Si is 0.3 to 0.94% by mass in terms of SiO, and the following Expression (1) is satisfied.1.3&#x2266;(Sr+Ba+Ca+2Na+2K)/Si&#x2266;5.7&#x2003;&#x2003;(1) [In Expression (1), Srrepresents an amount of Sr, on a molar basis, other than Sr which constitutes the Sr ferrite, and Ba, Ca, Na, and K represent amounts of respective elements on a molar basis.]

Provided is a sintered ferrite magnetthat contains Sr ferrite having a hexagonal crystal structure, wherein the total amount of Na and K is 0.01 to 0.09% by mass in terms of NaO and KO, an amount of Si is 0.1 to 0.29% by mass in terms of SiO, and the following Expression (1) is satisfied.2.5&#x2266;(Sr+Ba+Ca+2Na+2K)/Si&#x2266;5.4&#x2003;&#x2003;(1) [In Expression (1), Srrepresents an amount of Sr, on a molar basis, other than Sr which constitutes the Sr ferrite, and Ba, Ca, Na, and K represent amounts of respective elements on a molar basis.]

A motor control device that can reduce electrical noise is provided. A motor control device includes an inverter, a current controller, a high frequency wave superpositioner, and a high frequency wave setter. An inverter applies a current to the motor. A current controller outputs a voltage to the inverter according to a current applied to the motor from the inverter. A high frequency wave superpositioner applies a high frequency wave to the voltage from the current controller as a superpositioned wave to infer a position of a rotor in the motor. A high frequency wave setter varies at least one characteristic of the superpositioned wave applied by the high frequency wave superpositioner.

Motor control device

An oxide magnetic material is prepared by wet molding in a magnetic field a slurry containing a particulate oxide magnetic material, water and a polyhydric alcohol having the formula: C(OH)Hwherein n is from 4 to 100 as a dispersant. By improving the orientation in a magnetic field upon wet molding using water, an oxide magnetic material having a high degree of orientation, typically an anisotropic ferrite magnet, is obtained at a high rate of productivity. The method is advantageous from the environmental and economical standpoints.

Preparation of oxide magnetic material and oxide magnetic material

The present invention provides an oxide magnetic material, which includes a primary phase of a hexagonal ferrite containing metallic elements Ca, R, Fe and M, where M represents at least one element selected from the group including Co, Ni and Zn, and R represents at least one element selected from the group including Bi and rare earth elements including Y, with La being essentially included in R; wherein the proportions of the metallic elements Ca, R, Fe and M with respect to the total amount of the metallic elements are from 1 to 13 atomic % for Ca, from 0.05 to 10 atomic % for R, from 80 to 95 atomic % for Fe, and from 1 to 7 atomic % for M. The present invention also provides ferrite particles, a bonded magnet, a sintered magnet, a process for producing them, and a magnetic recording medium, which contain the oxide magnetic material.

Oxide magnetic material, ferrite particles, bonded magnet, sintered magnet, process for producing the same, and magnetic recording medium

The magnetic powder and the sintered magnet of the invention contains a primary phase of a hexagonal ferrite containing A, Co or R wherein A represents Sr, Ba or Ca, and R represents at least one element which may be rare earth elements including Y, and Bi, and have at least two different Curie temperatures. wherein the two different Curie temperatures are present within a range of from 400 to 480&deg; C., and an absolute value of a difference therebetween is 5&deg; C. or more. As both the saturation magnetization and the magnetic anisotropy of the M type ferrite therein are increased, the magnetic powder and the wintered magnet have a high residual magnetic flux density and a high coercive force, which conventional M type ferrite magnets could not have, while having excellent temperature characteristics of coercive force.

Magnet powder, sintered magnet, process for producing them, bonded magnet, motor and magnetic recording medium

An object of the invention is to simultaneously increase the saturation magnetization and magnetic anisotropy of M type ferrite, thereby realizing a hexagonal ferrite magnet having a high remanence and high coercivity which could never be achieved in prior art M type hexagonal ferrite magnets. The object is attained by a hexagonal ferrite magnet comprising A, R, and Fe, wherein A represents at least one element selected from among Sr, Ba, and Ca, and R represents an element capable of assuming a valence of &plus;3 or &plus;4 and having an ionic radius of at least 1.00 angstrom, and n/N is up to 0.35 provided that N is the total number of crystal grains and n is the number of crystal grains having stacking faults.

Growing community of inventors

Tokyo, Japan

Hitoshi Taguchi