Tdk Corporation

Chemirite, Ltd.

Teruo Mori

Hitoshi Taguchi

Taku Takeishi

Fumihiko Hirata

Seigo Tokoro

Katsunobu Okutani

Tohoru Murase

Naoe Hirai

Shiro Tomizawa

Toshihiro Suzuki

Shigeo Okamoto

Amer R Rathore

Takeshi Nomura

Junichi Takahashi

Kazutaka Suzuki

Katsuhiko Wakayama

Kiyoshi Uchida

Tomoko Nakamura

Hiraku Imaizumi

Takashi Shioura

Norishige Yamaguchi

Yoshimoto Odagawa

Yasushi Yanagisawa

Kazunori Hirose

Kazuhiro Okada

Kesaharu Takatoh

Naomichi Umehara

Hiroshi Eda

Yoshio Yamamoto

Kiyoshi Yanagisawa

A method for manufacturing a sintered compact includes the steps of preparing an alloy powder having a composition represented by Expression 1: RT(where, R is at least one kind of rare earth metal, T is at least one kind of transition metal, and w defines a relation of 1&#x3c;w&#x3c;4), sintering the alloy powder in a vacuum atmosphere or an atmosphere containing gas with a molecular weight of 30 or less, and processing the alloy powder by a hot isostatic pressing. The sintered compact has a high density, and reduces deteriorations in its sintered compact properties such as magnetostrictive properties in an air atmosphere at high-temperatures.

Method for preparing sintered product, sintered product and magnetostriction material

It is an object of the present invention to provide a method for producing a magnetostrictive element, capable of assuredly producing a magnetostrictive element by powder metallurgy. In a container for sintering, a compactis sintered into a magnetostrictive element having a composition of SmFewhile held by a supportof SmFeor Nb stable during the sintering step. The supportis composed of particles coming into contact with the compactat multiple points, to control fusion-bonding between the supportand the compactto a limited extent.

Method for producing magnetostrictive element and container for sintering

A pressure control apparatus according to the present invention is comprised of a magnetostrictive element section disposed between respective one ends of rotating rods which have the one ends thereof arranged on the same axis in a state connected to each other such that they are unrotatable relative to each other but at the same time are movable toward and away from each other, the rotating rods being rotatable about the axis in unison with each other, an urging means for urging the rotating rods to cause them to be closer to each other to thereby bring the respective one ends of the rotating rods into intimate contact with ends of the magnetostrictive element section, respectively, a magnetic field-applying means for generating a magnetic field for use in adjusting the length of the magnetostrictive element section to apply the magnetic field to the magnetostrictive element section, a pressure-detecting means for detecting pressure generated in the rotating rods in the direction of the axis, and a control section for controlling detected pressure such that it is constant, by controlling a strength of the magnetic field to adjust the length of the magnetostrictive element section.

Pressure control apparatus and rotation drive mechanism

An ultrasonic transducer includes a giant magnetostrictive rodof a columnar shape which is made of a giant magnetostrictive member, and vibration platesandwhich are made of plate members having a larger diameter than that of the giant magnetostrictive rodand are adhered and fixed to end surfaces in an axial direction of this giant magnetostrictive rod. The ultrasonic transducer can efficiently transmit ultrasonic vibration by expansion and contraction of the magnetostrictive rod in spite of a small and simple structure.

Ultrasonic transducer and ultrasonic vibration device using the same

Restoring magnetostriction characteristics without causing fusion of rod. By performing heat treatment on a giant magnetostrictive material within the temperature range of 750 to 860&#xb0; C., working distortion is removed while bleeding of an R-rich phase on a rod surface is prevented.

Giant magnetostrictive material and heat treatment method for giant magnetostrictive material

A torque sensor includes a substantially tubular giant magnetostrictive member, a shaft passing through the inner bore of the giant magnetostrictive member and capable of transmitting torque to the giant magnetostrictive member, and a detection coil for detecting changes in the magnetic permeability or remnant magnetization of the giant magnetostrictive member. Torque changes of the shaft are detected as changes in the magnetic permeability or remnant magnetization of the giant magnetostrictive member, based on the deformation of the giant magnetostrictive member. The torque sensor enables a reduction in the number of components and costs, as well as detection of torque changes with high sensitivity.

Torque sensing apparatus

A pressure sensorincludes a casingconfigured to be able to be filled with a fluidsuch as a liquid or a gas, in which at least part of a surface contacting this fluidis formed of a giant magnetostrictive membermade of a giant magnetostrictive element, and detecting means for detecting a change in magnetic permeability or an amount of remanent magnetization attributable to expansion and contraction of the giant magnetostrictive memberbased on a pressure change of the fluidfilled in this casingThe pressure sensorcan detect pressure at high sensitivity and high accuracy in a short time while achieving miniaturization of a device at the same time.

Scalable high sensitivity magnetostrictive pressure sensor

A contraction type actuatoris provided which can efficiently and evenly apply a bias magnetic field to a magnetostrictive rod to obtain a large contraction amount, while having a small and simple structure. In the contraction type actuator, a giant magnetostrictive rodflexibly expands and contracts by controlling the strength of a magnetic field applied by a magnet coil. A bias magnet comprises a first bias magnetand a second bias magnet. The fist bias magnetin an approximately cylindrical shape is coaxially disposed around the giant magnetostrictive rod. The second bias magnetis disposed in the inner spaceA of the first bias magnet, and is polarized in the direction of drawing a part of a magnetic field generated by the first bias magnetinto the inner spaceA.

Contraction type actuator

A weight sensorhaving a simple structure and yet being capable of detecting load or pressure of an object to be measured in a short time and with high sensitivity and high precision. The sensor includes a first rotating shaftvertically and rotatably supported on a stage, a second rotating shaftaxially and coaxially connected to the first rotating shaftwith a magnetostrictive memberinterposed therebetween for rotatably supporting an objectto be measured, and a pickup coilfor detecting changes in magnetic permeability or remnant magnetization of the magnetostrictive member. Load or pressure of the objectis detected as the changes in magnetic permeability or remnant magnetization, which are caused by extension and contraction of the magnetostrictive member

Weight-measuring sensor

In the step of sintering a compact that is finally to be a magnetostrictive element, when the temperature in a furnace is elevated, the atmosphere in the furnace is evacuated by a vacuum pump to keep the pressure in the furnace at negative pressure in a temperature range that allows thermal decomposition of hydride present in the compact to release hydrogen gas to accelerate release of hydrogen from the compact.

Method for producing magnetostrictive element and sintering method

To provide a method for producing a magnetostrictive material of excellent magnetostrictive characteristics. The method for producing a magnetostrictive material, wherein a mixture composed of Starting Materials A, B and C is sintered, where A is represented by Formula 1 (TbDy)T(T is at least one metallic element selected from the group consisting of Fe, Ni and Co, 0.35&#x3c;x&#x2266;0.50 and 1.70&#x2266;y&#x2266;2.00), B is represented by Formula 2 DyT(0.37&#x2266;t&#x2266;1.00), and C contains T, to produce a magnetostrictive material represented by Formula 3 (TbDy)T(0.27&#x2266;v&#x3c;0.50, and 1.70&#x2266;w&#x2266;2.00), wherein oxygen content is set at 500 to 3,000 ppm for Starting Material A and at 2,000 to 7,000 ppm for Starting Material B.

Method for producing magnetostrictive material

ferrite magnet raw material particles and a non-aqueous solvent is compacted wet in a magnetic field, while said non-aqueous solvent is removed therefrom, to obtain a compact, and the compact is sintered to obtain an anisotropic ferrite magnet. In this case, a surface active agent is allowed to exist in the slurry during the wet compaction. Alternatively, in addition to or in place of this, the raw material particles are pulverized to apply strains thereto, thereby reducing the iHc values to preferably 3.5 kOe or less. This makes some considerable improvement in the degree of orientation of the compact, thus achieving much more improved magnet properties.

Process for the production of anisotropic ferrite magnets and

To provide a multi-purpose type magnetostrictive device that may be used as an acceleration sensor or a vibration sensor capable of detecting forces acting in more than one direction and which may also be employed as a torque sensor, an actuator, a motor and the like. Coils 110 to 310 of magnetostrictive bodies 10 to 30 are wound around magnetostrictive members 120 to 320 in such a manner that voltages corresponding to enlongation/contraction of the magnetostrictive members 120 to 320 are generated. The magnetostrictive members 120 to 320 are each constrained at the two ends. The magnetic circuits 130 to 330 apply a bias magnetic field to the magnetostrictive members 120 to 320. The magnetostrictive bodies 10 to 30 are positioned so that they are all aligned in the direction of the Z axis which is taken in the direction of the two ends of each of the magnetostrictive members 120 to 320 and they are also arranged in such a manner that a relationship is maintained in which, on the flat plane formed by the X axis and the Y axis running at a right angle to the direction of the Z axis, a polygonal flat plane S is constituted by connecting the points P1 to P3 at which the magnetostrictive bodies 10 to 30 are positioned, the number of sides of which corresponds to the number of bodies.

Magnetostrictive device

A slurry containing ferrite magnet raw material particles and a non-aqueous solvent is compacted wet in a magnetic field, while said non-aqueous solvent is removed therefrom, to obtain a compact, and the compact is sintered to obtain an anisotropic ferrite magnet. In this case, a surface active agent is allowed to exist in the slurry during the wet compaction. Alternatively, in addition to or in place of this, the raw material particles are pulverized to apply strains thereto, thereby reducing the iHc values to preferably 3.5 kOe or less. This makes some considerable improvement in the degree of orientation of the compact, thus achieving much more improved magnet properties.

Hexagonal system ferrite particles and their production process

An anisotropic hexagonal barium ferrite sintered magnet is prepared by molding a powder barium ferrite raw material in a magnetic field into a compact and sintering the compact; or by molding a powder barium ferrite raw material in a magnetic field into a compact, disintegrating the compact into particles, compacting the particles in a magnetic field into a second compact, and sintering the second compact. In either case, the raw material contains calcined hexagonal barium ferrite, a silicon component, and a barium component. The resulting anisotropic hexagonal barium ferrite sintered magnet has improved sintered density and coercivity while the method minimizes deformation during sintering which is otherwise caused by the difference between the shrinkage factors in axis c and a directions, and simplifies or omits post-treatment like polishing.

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Tokyo, Japan

Teruo Mori