Tdk Corporation

Yoshihiko Minachi

Hitoshi Taguchi

Takahiro Mori

Hiroyuki Morita

Junichi Nagaoka

Kazumasa Iida

Noboru Ito

Kiyoyuki Masuzawa

Shigeki Yanagida

Masashi Gotoh

Nobuhiro Suto

Taku Murase

Yoshitaka Murakawa

Yuuki Aburakawa

Fumihiko Hirata

Naoto Tsukamoto

Naoharu Tanigawa

Mitsuaki Sasaki

Minao Himeno

Tatsuya Katoh

Tomohiko Aida

Shunsuke Kurasawa

Tatsuya Kato

Takeshi Masuda

Naoki Mori

Yoshinori Fujikawa

Hidenobu Umeda

Shinichi Sakano

Satoko Ueda

Kenya Takagawa

Kunio Ohno

Shunichi Kudo

Naoto Oji

Syunsuke Kurasawa

Miyuki Kawakami

Mitsuaki Sugiyama

Kikoyuki Masuzawa

Hideyuki Umezawa

Osanori Mizonoue

Yoshihiro Enda

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).

An object of the present invention is to provide a ferrite magnetic material which can provide a permanent magnet retaining high Br and HcJ as well as having high Hk/HcJ. The ferrite magnetic material according to a preferred embodiment is a ferrite magnetic material formed of hard ferrite, wherein a P content in terms of POis 0.001% by mass or more.

Ferrite magnetic material

An injection molding composition includes a ferrite powder which is a collection of ferrite particles, a first binder and a second binder, wherein a softening point of the second binder is lower than that of the first binder, a weight and a specific surface area of the ferrite powders are represented by Wp and S, and a weight and a density of the first binder and the second binder is represented by Wb1, Wb2, and Db1, Db2, and a hypothetical thickness Tb1 of the first binder is 0.6 to 3.0, and a hypothetical thickness Tb2 of the second binder is 5.0 to 16.0. In the composition, it is preferable that coated ferrite particles covering the outer circumference of the ferrite particles with the first binder and the second binder exist.1 [nm]=(1&#xd7;10)/(1&#xd7;)&#x2003;&#x2003;formula (1)2 [nm]=(2&#xd7;10)/(2&#xd7;)&#x2003;&#x2003;formula (2).

Injection molding composition and producing method thereof

An object of the present invention is to provide a ferrite magnetic material capable of providing a permanent magnet in which high Br and HcJ are kept, and which has a high Hk/HcJ. A ferrite magnetic material in accordance with a preferred embodiment has a ferrite phase having a hexagonal structure and has a main composition represented by CaRSrBaFeMO(R is at least one element of rare earth elements (including Y) essentially including La, and Bi, and M is at least one element of Co, Mn, Mg, Ni, Cu, and Zn essentially including Co), where 0.25&#x3c;w&#x3c;0.65, 0.01&#x3c;x&#x3c;0.45, 0.0002&#x3c;y&#x3c;0.011, y&#x3c;x, 8&#x3c;z&#x3c;11, 1.0&#x3c;w/m&#x3c;2.5, and 0.017&#x3c;m/z&#x3c;0.065 are satisfied. The total amount of a Si component is 0.1 to 3 mass % based on the amount of the main composition, and respective elements satisfy the relationship of 1.5&#x2266;[(Ca+R+Sr+Ba)&#x2212;(Fe+M)/12]/Si&#x2266;3.5.

A ferrite magnet and a ferrite sintered magnet including a ferrite magnetic material are provided. A main phase of the ferrite magnetic material includes a ferrite phase having a hexagonal crystal structure, and metal element composition expressed by Ca1-w-x-yR wSr xBayFezMm wherein 0.25&#x3c;w&#x3c;0.5, 0.01&#x3c;x&#x3c;0.35, 0.0001&#x3c;y&#x3c;0.013, y&#x3c;x, 8.7&#x3c;z&#x3c;9.9, 1.0&#x3c;w/m&#x3c;2.1, 0.017&#x3c;m/z&#x3c;0.055 and Si component is at least included as a sub-component, and wherein; when content y1 mass % of the Si component in the ferrite magnetic material, with respect to SiO2, is shown on Y-axis and a total content x1 of z and m is shown on X-axis, a relation between x1 and y1 is within a range surrounded by 4 points placed on X-Y coordinate having the X and Y axes.

Ferrite magnetic material, ferrite magnet, and ferrite sintered magnet

The present invention aims to ensure strength of a thin-walled sintered magnet. A sintered magnet is a ferrite sintered magnet made by sintering a magnetic material. A magnetic powder mixture obtained by mixing magnetic powder with a binder resin is injection-molded into a mold with a magnetic field applied thereto to produce a molded body, which is then sintered to produce the sintered magnet. The sintered magnet has a thickness of 3.5 mm or less in the position of center of gravity thereof. The sintered magnet has a surface roughness Rz of 0.1 &#x3bc;m or more and 2.5 &#x3bc;m or less. The surface roughness Rz is a 10 point average roughness.

Sintered magnet and method for producing the sintered magnet

A sintered ferrite magnet having a ferrite phase with a hexagonal structure as the main phase, wherein the composition of the metal elements composing the main phase is represented by the following general formula (1):RCaA(FeM): &#x2003;&#x2003;(1),x, m, y and z in formula (1) satisfying all of the conditions represented by the following formulas (2)-(6):0.2&#x2266;&#x2266;0.5: &#x2003;&#x2003;(2)0.13&#x2266;&#x2266;0.41: &#x2003;&#x2003;(3)0.70.15: &#x2003;&#x2003;(4)0.18&#x2266;&#x2266;0.31: &#x2003;&#x2003;(5)9.6&#x2266;12&#x2266;11.8: &#x2003;&#x2003;(6),and wherein the density of the sintered ferrite magnet is at least 5.05 g/cm, and the crystal grains of the sintered ferrite magnet satisfy all of the conditions represented by the following formulas (7) and (8), where L &#x3bc;m is the average for the maximum value and S &#x3bc;m is the average for the minimum value among the diameters passing through the center of gravity of each grains in the crystal cross-section parallel to the c-axis direction of hexagonal structures.&#x2266;0.95: &#x2003;&#x2003;(7)1.8&#x2266;&#x2266;2.5: &#x2003;&#x2003;(8).

Ferrite sintered magnet

A ferrite sintered magnet has a surface roughness Rz of 3.5 &#x3bc;m or less. A method for producing a ferrite sintered magnet includes: mixing magnetic powders with at least a binder resin to obtain a magnetic powder mixture; injection molding the magnetic powder mixture inside of a mold having a surface roughness of a surface in contact with the magnetic powder mixture of 2.0 &#x3bc;m or less with a magnetic field applied to the mold, to obtain a molded body; and sintering the molded body.

Ferrite sintered magnet, motor, and method for producing the ferrite sintered magnet

An injection molding composition, having a small fluctuation characteristic and a better characteristic, is provided. The above composition is the injection molding composition comprising a ferrite powder which is a collection of ferrite particles, a first binder and a second binder. A weight and a specific surface area of the ferrite powders are represented by Wp and S, and a weight and a density of the first binder and the second binder is represented by Wb, Wb, and Db, Db. A hypothetical thickness Tbof the first binder is 2.0 to 15.0, and a hypothetical thickness Tbof the second binder is 16.5 to 32.0. In the composition, it is preferable that coated ferrite particles coating the outer circumference of the ferrite particles with the first binder and the second binder exist.1 [nm]=(1&#xd7;10)/(1&#xd7;)&#x2003;&#x2003;formula (1)2 [nm]=(2&#xd7;10)/(2&#xd7;)&#x2003;&#x2003;formula (2)

A method for producing a sintered magnet comprising steps of; wet-pulverizing a magnetic powder under the presence of a surface active agent, drying said wet-pulverized magnetic powderfor obtaining magnetic powder to which said surface active agent is adhered,

Method for producing sintered magnet

The present invention provides a ferrite magnetic material capable of attaining such magnetic properties that Br+(&#x2153;)HcJ is 6200 or more even by sintering at a temperature of 1150&#xb0; C. or lower. The ferrite magnetic material includes as a main phase thereof a ferrite phase having a hexagonal structure, the main phase being represented by the following composition formula (1): LaCa&#x3b1;(FeCo)with &#x3b1; representing one or two of Ba and Sr; wherein the constituent ratios of the metal elements constituting the main phase satisfy the following conditions: x and m are the values in a region bounded by the points, A: (0.53, 0.27), B: (0.64, 0.27), C: (0.64, 0.35), D: (0.53, 0.45), E: (0.47, 0.45) and F: (0.47, 0.32) in the (x, m) coordinates shown in FIG.; 1.3&#x2266;x/yz&#x2266;1.8; and 9.5&#x2266;12z&#x2266;11.0.

A ferrite magnet powder is represented by the composition formula AFeMFeO, wherein A represents at least one element selected from the group consisting of Sr, Ba, and Pb; and M represents at least one element selected from the group consisting of Zn, Co, Mn, and Ni, and wherein 0.05&#x2266;x&#x2266;0.80, 1.5&#x2266;a&#x2266;2.2, and 12&#x2266;b&#x2266;17. A high saturation magnetization 4&#x3c0;Is can be achieved by the partial substitution of the Fesite of a W-type ferrite with an element M such as Zn within a certain range.

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Tokyo, Japan

Yoshihiko Minachi