Sumitomo Special Metals Co., Ltd.

Neomax Co., Ltd.

Hitachi Metals, Ltd.

Kohshi Yoshimura

Fumiaki Kikui

Takeshi Nishiuchi

Masahiro Asano

Takahiro Isozaki

Tomoori Odaka

Hideyuki Morimoto

Shigeru Takaki

Shuji Tsujimoto

Shinichiro Sakashita

Tomoiku Otani

Kaoru Kojima

Yoriyoshi Oooka

Kazuhide Oshima

An R&#x2014;Fe&#x2014;B based anisotropic sintered magnet according to the present invention has, as a main phase, an RFeB type compound that includes a light rare-earth element RL (which is at least one of Nd and Pr) as a major rare-earth element R, and also has a heavy rare-earth element RH (which is at least one element selected from the group consisting of Dy and Tb). In the crystal lattice of the main phase, the c-axis is oriented in a predetermined direction. The magnet includes a portion in which at least two peaks of diffraction are observed within a 2&#x3b8; range of 60.5 degrees to 61.5 degrees when an X-ray diffraction measurement is carried out using a CuK &#x3b1; ray on a plane that is located at a depth of 500 &#x3bc;m or less under a pole face of the magnet and that is parallel to the pole face.

R-Fe-B anisotropic sintered magnet

An R&#x2014;Fe&#x2014;B based rare-earth sintered magnet according to the present invention includes, as a main phase, crystal grains of an RFeB type compound that includes Nd, which is a light rare-earth element, as a major rare-earth element R. The magnet includes a heavy rare-earth element RH (which is at least one of Dy and Tb) that has been introduced through the surface of the sintered magnet by diffusion. The magnet has a region in which the concentration of the heavy rare-earth element RH in a grain boundary R-rich phase is lower than at the surface of the crystal grains of the RFeB type compound but higher than at the core of the crystal grains of the RFeB type compound.

R-Fe-B rare earth sintered magnet

A copper plating solution according to the present invention is characterized by that it comprising 0.03 mol/L to 0.5 mol/L of copper sulfate, 0.05 mol/L to 0.7 mol/L of ethylenediaminetetraacetic acid and 0.02 mol/L to 0.3 mol/L of sulfite, and has a pH adjusted to 5.0 to 8.5. A method for copper plating according to the present invention is characterized by that it comprises using the copper plating solution above. The copper plating solution and the method for copper plating according to the present invention stably provide a uniform copper plating film excellent in adhesion on the surface of an article to be plated, such as rare earth metal-based permanent magnet.

Copper plating solution and method for copper plating

An object of the present invention is to provide a method for forming a uniform and dense electroplating film with high adhesion strength on the surface of an article, yet irrespective of the surface material and the surface properties of the article. A means for a solution of the problem comprises: forming on the surface of the article, a resin coating made of a resin containing dispersed therein a powder of a first metal; then forming a second-metal substituted plating film on the surface of the resin coating by immersing the resin-coated article in a solution containing ions of a second metal having an ionization potential nobler than that of the first metal; and further forming an electroplating film of a third metal on the surface of the metal-substituted plating film.

Method for forming electroplating film on surfaces of articles

The objectives of the present invention are to provide a stable and simple method for producing a rare earth metal-based permanent magnet having on the surface thereof a corrosion-resistant film containing fine zinc particles dispersed therein, a corrosion-resistant rare earth metal-based permanent magnet produced by the method, a dip spin coating method being suitable for forming a coating film on thin type work pieces having various shapes, and a method for forming a coating film on a work piece. A method for producing a corrosion-resistant rare earth metal-based permanent magnet of the present invention, characterized in that it comprises providing an aqueous treating fluid, which contains a hydrolysis polymerization product of alkyl silicate and fine zinc particles having an average particle diameter of 1 &#x3bc;m to 50 &#x3bc;m and has a pH value of 6 to 8 and a viscosity of 1000 cP or less, applying the fluid on the surface of a rare earth metal-based permanent magnet, and subjecting the resultant magnet to a heat treatment at 250&#xb0; C. to 400&#xb0; C., to thereby form a corrosion-resistant film containing fine zinc particles dispersed therein.

Method for producing corrosion-resistant rare earth metal-based permanent magnet

A rare earth metal-based permanent magnet has a film layer formed substantially of only a fine metal powder on a metal forming the surface of the magnet. The rare earth metal-based permanent magnet having the film layer on its surface is produced in the following manner: A rare earth metal-based permanent magnet and a fine metal powder forming material are placed into a treating vessel, where both of them are vibrated and/or agitated, whereby a film layer made of a fine metal powder produced from the fine metal powder producing material is formed on a metal forming the surface of the magnet. Thus, the formation of a corrosion-resistant film such as plated film can be achieved at a high thickness accuracy by forming an electrically conductive layer uniformly and firmly on the entire surface of the magnet without use of a third component such as a resin and a coupling agent.

Rare earth metal-based permanent magnet, and process for producing the same

An electroplating device including an anode inserted through and disposed in a hole provided in a work and communicating with the outside, and a member for rotating the work about its center axis and supplying a plating electric current to the work. Alternatively, a separate member may supply the plating electric current to the work. A plating solution in the hole in the work may be allowed to flow. Thus, a uniform plated film can be formed on both of the outer and inner surfaces of the work having the communicating with the outside such as a ring-shaped work, of which a ring-shaped bonded magnet is representative, by using the electroplating device.

Electroplating device, and process for electroplating work using the device

A resin molded product and a fine metal powder producing material are placed into a treating vessel. The fine metal powder producing material is brought into flowing contact with the surface of the resin molded product, thereby producing a fine metal powder, and forming a metal layer of the fine metal powder on the surface of the resin molded product. In this process, the metal layer of the fine metal powder can be formed firmly and at high density on the surface of the resin molded product. The metal layer exhibits a function as an electrically conductive layer. Therefore, a metal film having an excellent thickness accuracy, an excellent surface smoothness and a high peel strength can be formed in a simple manner on the metal layer by carrying out an electroplating treatment. In addition, it is possible for the metal layer itself to exhibit functions or properties such as an ornamentality.

Process for forming metal layer on surface of resin molded product

A hollow work having a hole communicating with the outside and a fine metal powder producing material are placed into a treating vessel, where the fine metal powder producing material is brought into flowing contact with the surface of the work, thereby adhering a fine metal powder produced from the fine metal powder producing material to the surface of the work. The hollow work may be a ring-shaped bonded magnet. Thus, a film having an excellent corrosion resistance can be formed without use of a third component such as a resin and a coupling agent by providing an electric conductivity to the entire surface of the magnet, i.e., not only to the outer surface (including end faces) but also to the inner surface of the magnet and subjecting the magnet to an electroplating treatment.

Process for surface-treatment of hollow work having hole communicating with outside, and ring-shaped bonded magnet produced by the process

The integrated magnet body according to the invention is an integrated magnet body formed by laminating and securing a plurality of pieces of magnet through an insulating film between pieces of magnet, characterized in that the insulating film has a film thickness of 0.01 &mgr;m or more, and a ratio of a total sum of the thickness of the insulating films to an overall length in the laminating direction of the integrated magnet body is in a range of from 0.0005 to 3%. The integrated magnet body according to the invention is excellent in insulating property and effective volume ratio and thus can attain high efficiency of a motor by installing the integrated magnet body in the motor.

Integrated magnet body and motor incorporating it

An Fe&mdash;B&mdash;R based permanent magnet has a metal oxide film having a thickness of 0.01 &mgr;m to 1 &mgr;m on its surface with a metal film interposed therebetween. Thus, the film is excellent in adhesion to the surface of the magnet. Even if the permanent magnet is left to stand under. high-temperature and high-humidity of a temperature of 80&deg; C. and a relative humidity of 90% for a long period of time, the magnetic characteristic of the magnet cannot be degraded. The magnet has a thermal shock resistance enough to resist even a heat cycle for a long period of time in a temperature range of &minus;40&deg; C. to 85&deg; C., and can exhibit a stable high magnetic characteristic. Therefore, it is possible to produce an Fe&mdash;B&mdash;R based permanent magnet having a corrosion-resistant film free from hexa-valent chromium.

FE-B-R based permanent magnet having corrosion-resistant film, and process for producing the same

A molded product having pores in its surface, an inorganic powder, a fat and oil and media are placed into a treating vessel, and a kinetic energy is supplied to the contents of the treating vessel, thereby forcing the inorganic powder into the pores and hardening it in the pores. In another process, a molded product having pores in its surface and an inorganic powder producing material are placed into a treating vessel, and a kinetic energy is supplied to the contents of the treating vessel, thereby forcing an inorganic powder produced from the inorganic powder producing material into the pores and hardening it in the pores. The inorganic powder producing material performs a role of producing an inorganic powder by the collision of pieces of the inorganic powder producing material against one another, against the molded product and against the inner wall of the vessel, and a role as media for forcing the produced inorganic powder into the pores. Thus, a pore sealing effect can be achieved by cooperation of these roles. Therefore, the process according to the present invention can be carried out selectively and simply in a dry manner for the pores in the molded product to exhibit a pore sealing effect. Then, a corrosion-resistant film such as a plated film having dimensional accuracy can be formed on the surface of the molded product in a subsequent step without exertion of an influence to the surface accuracy of the molded product.

Process for sealing pores in molded product, and bonded magnet with pores sealed by the process

An Fe&mdash;B&mdash;R based permanent magnet has a metal oxide film having a thickness of 0.01 &mgr;m to 1 &mgr;m on its surface with a metal film interposed therebetween. Thus, the film is excellent in adhesion to the surface of the magnet. Even if the permanent magnet is left to stand under high-temperature and high-humidity of a temperature of 80&deg; C. and a relative humidity of 90% for a long period of time, the magnetic characteristic of the magnet cannot be degraded. The magnet has a thermal shock resistance enough to resist even a heat cycle for a long period of time in a temperature range of &minus;40&deg; C. to 85&deg; C., and can exhibit a stable high magnetic characteristic. Therefore, it is possible to produce an Fe&mdash;B&mdash;R based permanent magnet having a corrosion-resistant film free from hexa-valent chromium.

Process for producing Fe-B-R based permanent magnet having corrosion-resistant film

A method of manufacturing R&mdash;Fe&mdash;B bonded magnets, capable of forming various corrosion resisting films on a R&mdash;Fe&mdash;B bonded magnet uniformly with a very high bonded strength so as to attain such a very high corrosion resistance thereof that prevents the bonded magnet from being rusted even in a long-period high-temperature high-humidity test; comprising barrel-polishing a porous R&mdash;Fe&mdash;B bonded magnet by a dry method using as media an abrasive stone formed by sintering inorganic powder of Al O , SiC, ZrO and MgO, or a mixture of an abrasive for metal balls and vegetable media, such as vegetable skin chips, sawdust, rind of a fruit and a core of corn, or a mixture of vegetable media the surfaces of which are modified by the above-mentioned abrasive and the above-mentioned inorganic pulverized bodies, so as to enable a surface of the magnet to be smoothed and sealed.

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Osaka, Japan

Kohshi Yoshimura