Patents Assigned to Dowa Mining Co., Ltd.
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Patent number: 5676769Abstract: A treating material W pre-heated to a carburizing temperature of 750.degree.-950.degree. C. is heat-treated in a carburizing atmosphere directly supplied with hydrocarbon and oxidizing gases and heated to 1000.degree.-1100.degree. C. Then, the treating material W is forcibly cooled to a temperature below 600.degree. C., the treating material W is re-heated to 750.degree.-850.degree. C., and then it is hardened.Energy required to the carburization can be saved because drastic reduction of the treating time is possible.Type: GrantFiled: January 19, 1996Date of Patent: October 14, 1997Assignee: Dowa Mining Co. Ltd.Inventors: Toshiyuki Kawamura, Hitoshi Goi, Atsushi Murayama, Hirofumi Kamisugi
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Patent number: 5652042Abstract: A conductive paste compound for via hole filling includes a conductive filler at 80 to 92 weight percent with an average particle size of from 0.5 to 20 .mu.m and specific surface of from 0.1 to 1.5 m.sup.2 /g, a liquid epoxy resin at 4.5 to 20 weight percent containing 2 or more epoxy groups with room temperature viscosity of 15 Pa.multidot.sec or less, and a hardener at 0.5 to 5 weight percent, wherein the viscosity is 2,000 Pa.multidot.sec or less and the volatile amount is 2.0 weight percent or less. A filling paste and a printed circuit board with use thereof are provided which can conduct an inner-via-hole connection between electrode layers without using a through-hole plating technique.The conductive paste comprises a metallic particle such as copper, an epoxy resin, a hardener, and if necessary, a dispersant. The paste having low viscosity and low volatility under high shear is used to fill holes disposed in a laminated substrate.Type: GrantFiled: October 28, 1994Date of Patent: July 29, 1997Assignees: Matsushita Electric Industrial Co., Ltd., Dai-Ichi Kogyo Seiyaku Co., Ltd., Dowa Mining Co., Ltd.Inventors: Kouji Kawakita, Seiichi Nakatani, Tatsuo Ogawa, Masatoshi Suehiro, Kouichi Iwaisako, Hideo Akiyama
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Patent number: 5630554Abstract: To insure that rejects or scraps of composite materials such as printed wiring boards that consist of the mixture of metal and non-metal parts are separated into the metal and non-metal components with good precision so that both components can be recovered as recyclable valuables, the composite materials are broken into pieces by means of a shearing machine or the like and the pieces are thereafter ground with a hammer mill or the like to form a mixed powder consisting of metal and non-metal particles, which mixed powder is then fed continuously on to a belt conveyor inclined at an angle with respect to a line perpendicular to the direction of travel, whereby the metal particles are efficiently separated from the non-metal particles; the recovered metal particles being fed to an electrostatic separator to obtain higher grade of concentration by removing the non-metal inclusions.Type: GrantFiled: February 21, 1995Date of Patent: May 20, 1997Assignees: Dowa Mining Co., Ltd., Jiro HiraishiInventors: Chiaki Izumikawa, Hiroyuki Iwata, Shigehisa Endoh, Hitoshi Ohya
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Patent number: 5591535Abstract: There is provided an accicular ferromagnetic metal powder with which one can produce magnetic media for high-density recording that are improved in storage stability and magnetic characteristics.The improved ferromagnetic metal powder essentially consists of iron and 50 atm % based on the amount of iron of cobalt and at least one of aluminum and yttrium or any other rare earth element and contains no more than 0.05 wt % of an element of Group Ia of the periodic table (Li, Na, K). The amount of aluminum is in the range of 0.1-30 atm %, the amount of yttrium or any other rare earth element is in the range of and 0.1-10 atm %, each being based on the total quantity of the metal elements present. In either of these cases, the residue of an element of Group IIa of the periodic table (Mg, Ca, Sr, Ba) is preferably 0.1 wt % or less.Type: GrantFiled: May 1, 1995Date of Patent: January 7, 1997Assignee: Dowa Mining Co., Ltd.Inventors: Seiichi Hisano, Kazuhisa Saito, Satoshi Aizawa, Kazushi Sano, Kazuyuki Matsumoto, Kenji Murata
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Patent number: 5554219Abstract: When producing a single-crystal bulk ZnSe from a melt by a high-pressure melt technique in a vertical Bridgman (VB) furnace or a vertical gradient freezing (VGF) furnace, preliminarily grown polycrystalline ZnSe (which may be a crystal solely composed of twins) is used as a seed and, after melting the starting ZnSe material and part of the seed, a twin-free ZnSe bulk crystal is grown on the seed; alternatively, polycrystalline ZnSe is grown at the tip of the growing crystal and part of it is melted, followed by growing a single crystal on that polycrystal to produce a twin-free, high-purity ZnSe bulk crystal. In either way, the process assures that twin-free single crystals of bulk ZnSe can be produced with good reproducibility without adding dopants or using any materials that are difficult to obtain.Type: GrantFiled: January 23, 1995Date of Patent: September 10, 1996Assignee: Dowa Mining Co., Ltd.Inventors: Tsuguo Fukuda, Peter Rudolph, Kazuyuki Umezu
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Patent number: 5534361Abstract: There is provided a metallic magnetic powder with which one can produce magnetic media for high-density recording that are improved in storage stability and magnetic characteristics.The improved ferromagnetic metal powder contains no more than 0.05 wt % of an element of Group Ia of the periodic table. The powder may optionally contain 0.1-30 atm % of aluminum and/or 0.1-10 atm % of Y or any other rare earth element based on the total quantity of the metal elements present. In either of these cases, the residue of an element of Group IIa of the periodic table is preferably 0.1 wt % or less.Type: GrantFiled: June 27, 1994Date of Patent: July 9, 1996Assignee: Dowa Mining Co., Ltd.Inventors: Seiichi Hisano, Kazuhisa Saito, Satoshi Aizawa, Kazushi Sano, Kazuyuki Matsumoto, Kenji Murata
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Patent number: 5462821Abstract: A novel primary or secondary battery whose active material for the negative electrode is composed of metallic gallium, gallium alloys or gallium oxide has first come into the world.Gallium has an electrochemical equivalent of 23.24, which is smaller than those of zinc (32.70) and cadmium (56.21). This indicates that when used as an active material for the negative electrode in batteries, gallium has larger capacity per unit mass than zinc and cadmium by respective factors of ca. 1.4 and 2.4. The potential of the reaction; Ga+6OH.sup.- =GaO.sub.3.sup.3- +3H.sub.2 O+3e.sup.- is obviously less noble than the voltage of hydrogen evolution and this means that a high-potential battery can be made. Due to the high hydrogen overvoltage of gallium, gallium ions in the solution can be precipitated as metallic gallium by electrodeposition. As a further advantage, no dendrite formation occurs during the electrodeposition unlike in the case of zinc.Type: GrantFiled: November 16, 1994Date of Patent: October 31, 1995Assignee: Dowa Mining Co., Ltd.Inventors: Takashi Onoue, Kiyoshi Araki, Noriya Ishida, Toshiya Kitamura, Yasuhiko Niitsu, Makiko Yanagisawa, Ryo Sakamoto, Fumihiro Sato
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Patent number: 5387293Abstract: A copper base alloy for terminals that is of the Cu-Ni-Sn-P or Cu-Ni-Sn-P-Zn system and that has a tensile strength of at least 50 kgf/mm.sup.2, a spring limit of at least 40 kgf/mm.sup.2, a stress relaxation of not more than 10% and a conductivity of at least 30% IACS is provided. Terminals the spring portion or the entire part of which is produced from that copper base alloy, having an insertion/extraction force of 0.2-3 kgf and a resistance of not more than 3 m.OMEGA. at low voltage and current as initial performance, with the added characteristic that the terminals will experience not more than 20% stress relaxation are also provided. The alloy is superior to the conventional bronze, phosphor bronze and Cu-Sn-Fe-P alloys for terminals in terms of tensile strength, spring limits, stress relaxation characteristic and conductivity and, hence, the terminals manufactured from those alloys have higher performance and reliability than the terminals made of the conventional copper base alloys for terminals.Type: GrantFiled: March 24, 1993Date of Patent: February 7, 1995Assignees: Dowa Mining Co., Ltd., Yazaki Corporation, Nihon Bell Parts Co., Ltd.Inventors: Takayoshi Endo, Kenji Takenouchi, Mikio Nishihata, Toshio Asano, Akira Sugawara
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Patent number: 5348888Abstract: Microorganisms of the genus Thiobacillus find utility in the mining industry in such applications as bacterial leaching, the treatment of mine drainage water and the deiron in hydrometallurgy process. This invention discloses a DNA fragment which codes for a mercuric reductase in microorganisms of the genus Thiobacillus and is useful in constructing a new strain of Thiobacillus ferrooxidans capable of fast growth. A recombinant plasmid incorporating the DNA fragment, a shuttle vector plasmid incorporating the DNA fragment, host cells and a method of transforming the host cells are also disclosed.Type: GrantFiled: October 8, 1993Date of Patent: September 20, 1994Assignee: Dowa Mining Co., Ltd.Inventors: Toshikazu Shiratori, Chihiro Inoue, Yoshichika Kitagawa, Tomonobu Kusano
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Patent number: 5322575Abstract: A copper base alloy for terminals that is superior in all aspects of tensile strength, spring limits, conductivity, and stress relaxation characteristics can be produced by a process repeating the cycles consisting of hot-rolling, cold-rolling and annealing, in which process an ingot is prepared by melting and casting an alloy containing 1.0-3.0 wt % Ni, 0.02-0.15 wt % P. 0.5-2.0 wt. % Sn and, as an optional component, 0.01-2.0 wt % Zn, with the balance being Cu and incidental impurities, and with the ratio of weight percentages of Ni to P being within the range of 10-50%.Type: GrantFiled: March 24, 1993Date of Patent: June 21, 1994Assignees: Dowa Mining Co., Ltd., Yazaki Corporation, Nihon Bell Parts Co., Ltd.Inventors: Takayoshi Endo, Kenji Takenouchi, Mikio Nishihata, Toshio Asano, Akira Sugawara
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Patent number: 5269855Abstract: A permanent magnet made of an R--Fe--B--C or R--Fe--Co--B--C based alloy, where R is at least one rare-earth element, comprising individual magnetic crystal grains that are covered with an oxidation-resistant protective film. The protective film surrounding the individual magnetic crystal grains having a thickness of 0.001-30 .mu.m and 0.05-16 wt. % of the protective film comprising C.Type: GrantFiled: February 27, 1992Date of Patent: December 14, 1993Assignee: Dowa Mining Co., Ltd.Inventors: Toshio Ueda, Yuichi Sato, Seiji Isoyama, Seiichi Hisano
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Patent number: 5268040Abstract: A method of cooling steel parts from austenitic stage to a temperature that is higher than its Ms point after carburization of said steel part to carry out diffusion transformation, then carrying out a nitriding treatment and further applying shot peening, and in order to implement said method provide a carburizing zone, a cooling zone for carrying out diffusion transformation and a nitriding treatment zone connected through opening and shutting doors, and provide feeding devices in each of said zones to feed the steel parts to the next zone.Type: GrantFiled: October 2, 1992Date of Patent: December 7, 1993Assignee: Dowa Mining Co., Ltd.Inventors: Takeshi Naito, Masahiro Azumi
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Patent number: 5252305Abstract: A process of recovering a platinum group metal from a waste catalyst comprising a first step which comprises heating and melting the catalyst impregnated with the platinum group metal, copper and/or the oxide of copper, a flux component and a reductant component to form a layer containing the metal copper into which the platinum group metal is absorbed and another layer of the oxide, and then separating the metal copper; and a second step which comprises supplying air or oxygen as an oxidant to the separated metal copper for oxidizing under heating and melting to form a layer of partially oxidized metal copper and another layer of the metal copper containing the concentrated platinum group metal, and separating it. This process enables the economical recovery of the platinum group metal from the waste catalyst in a short period of time with high recovery rate.Type: GrantFiled: April 9, 1992Date of Patent: October 12, 1993Assignees: Tanaka Kikinzoku Kogyo K.K., Dowa Mining Co., Ltd., Kosaka Smelting & Refining Co., Ltd.Inventors: Nobuyasu Ezawa, Hiroshi Inoue, Shoei Takada, Hitoshi Masuda
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Patent number: 5205878Abstract: Electric and electronic parts, including leadframes made of a copper-based alloy having high strength and high electric conductivity said copper-based alloy is produced by a process which comprises the steps of preparing a copper-based alloy consisting essentially of 0.01-3.0 wt % Co and 0.01-0.5 wt % P with the balance being Cu and incidental impurities, quenching said alloy from a temperature not lower than 750.degree. C. down to 450.degree. C. and below at a cooling rate of at least 1.degree. C./sec, heat treating the quenched alloy at a temperature of 480.degree.-600.degree. C. for 30-600 minutes, cold working said alloy for a working ratio of 20-80%, further heat treating the alloy at a temperature of 440.degree.-470.degree. C. for 30-600 minutes, and subsequently performing cold working for a working ratio of at least 50% and heat treatment at 380.degree. C. and below. The electric and electronic parts preferably contain a plurality of conductive leads.Type: GrantFiled: December 16, 1991Date of Patent: April 27, 1993Assignee: Dowa Mining Co., Ltd.Inventors: Toshihiro Kanzaki, Akira Sugawara, Isamu Amatsu, Kouichi Hatakeyama
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Patent number: 5183630Abstract: A process for producing a permanent magnet alloy based on a R--Fe--B--C system wherein R is at least one of the rare earth elements including Y, comprising the steps of preparing a molten crude alloy, producing a powder directly therefrom or after casting it into an alloy ingot and then grinding it into the powder, compacting the thus obtained powder and sintering the compacted product, the ingot or powder of the alloy before being sent to the compacting step being subjected to a heat treatment which is carried out at a temperature of 500.degree.-1,100.degree. C. for a period of 0.5 hour or more so as to produce a permanent magnet alloy based on an a R--Fe--B--C system whose individual magnetic crystal grains are covered with an oxidation-resistant protective film which has a C content higher than that of the individual crystal grains.Type: GrantFiled: June 4, 1991Date of Patent: February 2, 1993Assignee: Dowa Mining Co., Ltd.Inventors: Toshio Ueda, Yuichi Sato, Masayasu Senda, Seiji Isoyama, Seiichi Hisano
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Patent number: 5174363Abstract: Molten metal is poured into a mold having an inside cross section with varied thicknesses along the direction of the width thereof. The molten metal is allowed to solidify in the mold and the cast strip is withdrawn from the mold either continuously or intermittently. The as-cast strip is rolled at either identical or similar thickness reduction ratios in the direction of width of the strip. This process enables the production of high quality shape strips free from any substantial working deformation in the workpiece.Type: GrantFiled: April 22, 1991Date of Patent: December 29, 1992Assignee: Dowa Mining Co., Ltd.Inventors: Masahiro Furo, Hitoshi Endou, Tadao Hishinuma
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Patent number: 5147473Abstract: A permanent magnet made of an R-Fe-B-C or R-Fe-Co-B-C based alloy (where R is at least one rare-earth element) consisting of its individual magnetic crystal grains that are covered with an oxidation-resistant protective film is promising as a practicable next-generation magnet because of its having not only excellent magnetic properties inclusive of magnetic force that surpasses Sm-Co based magnets but also such highly improved oxidation resistance that may withstand use in practical applications for a prolonged time period without being coated on its outermost exposed surface with an oxidation-resistant protective film. Said protective film surrounding the individual magnetic crystal grains contains at least one, preferably substantially all, of the alloying elements of which said magnetic crystal grains are made, with 0.05-16 wt. %, preferably 0.1-16 wt. % of said protective film being composed of C.Type: GrantFiled: August 9, 1990Date of Patent: September 15, 1992Assignee: Dowa Mining Co., Ltd.Inventors: Toshio Ueda, Yuichi Sato, Masayasu Senda, Seiji Isoyama, Seiichi Hisano
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Patent number: 5147469Abstract: Copper-based alloys suitable for use as materials in fabricating electric and electronic parts as typified by leadframes and having high strength and high electric conductivity can be produced by a process which comprises the steps of preparing a copper-based alloy consisting essentially of 0.01- 3.0 wt % Co and 0.01- 0.5 wt % P with the balance being Cu and incidental impurities, quenching said alloy from a temperature not lower than 750.degree. C. down to 450.degree. C. and below at a cooling rate of at least 1.degree. C./sec, heat treating the quenched alloy at a temperature of 480.degree.-600.degree. C. for 30-600 minutes, cold working said alloy for a working ratio of 20-80%, further heat treating the alloy at a temperature of 440.degree.-470.degree. C. for 30-600 minutes, and subsequently performing cold working for a working ratio of at least 50% and heat treatment at 380.degree. C. and below.Type: GrantFiled: November 14, 1991Date of Patent: September 15, 1992Assignee: Dowa Mining Co. Ltd.Inventors: Toshihiro Kanzaki, Akira Sugawara, Isamu Amatsu, Kouichi Hatakeyama
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Patent number: 5117100Abstract: The present optical position detection method and the apparatus therefor is adapted to compute an arithmetic mean of the adjusted light reception values received by adjacent photodetectors as the virtual light reception value at the virtual position, compare not only the adjusted light reception values of the respective photodetectors but also the virtual light reception values with the reference level and utilize the virtual position also as the light interruption position data when light interruption is determined, thus enhancing the accuracy of detecting the position of an object.Type: GrantFiled: December 27, 1990Date of Patent: May 26, 1992Assignee: Dowa Mining Co., Ltd.Inventors: Shigeo Yoshida, Isamu Fujimoto, Hideyuki Suzuki, Hiroshi Asano, Toru Hosaka, Takashi Onioh, Kojyu Nagasaki, Kenichi Matsuoka, Kazufumi Taura
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Patent number: 5082163Abstract: A non-oxide ceramic material such as aluminum nitride can be metallized with copper by directly bonding a thin sheet of copper to a substrate of the non-oxide ceramic material instead of using a conventional manner in which a paste comprising a powder of copper and a binder is applied to a ceramic substrate by printing. This metallization is effected by placing the non-oxide ceramic material either in contact with or in close proximity to copper containing a copper oxide, followed by heating them in a non-oxidizing atmosphere at a temperature lower than the melting point of copper, but at which the dissociation of the copper oxide contained in copper can occur, so as to dissociate at least part of the copper oxide into metallic copper and oxygen to thereby provide a strong bondage between the surfaces of said non-oxide ceramic material and copper. The metallized non-oxide ceramic material can be used as a substrate for use in IC devices.Type: GrantFiled: December 15, 1989Date of Patent: January 21, 1992Assignee: Dowa Mining Co., Ltd.Inventors: Naoyuki Kanahara, Tetsuo Furihata