Patents Assigned to Dowa Mining Co., Ltd.
  • Patent number: 8992701
    Abstract: After a reducing agent is added to a water reaction system containing silver ions to deposit silver particles by reduction, the silver particles are dried to obtain a silver powder which is heat-treated at a temperature of higher than 100° C. and lower than 400° C. The silver powder thus heat-treated has a maximum coefficient of thermal expansion of not greater than 1.5% at a temperature of 50° C. to 800° C., and has no heating peak when the silver powder is heated from 50° C. to 800° C. The silver powder has an ignition loss of not greater than 1.0% when the silver powder is ignited until the weight of the silver powder is constant at 800° C. The silver powder has a tap density of not less than 2 g/cm3 and a BET specific surface area of not greater than 5 m2/g.
    Type: Grant
    Filed: May 10, 2012
    Date of Patent: March 31, 2015
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Takatoshi Fujino, Kozo Ogi
  • Patent number: 8282702
    Abstract: After a reducing agent is added to a water reaction system containing silver ions to deposit silver particles by reduction, the silver particles are dried to obtain a silver powder which is heat-treated at a temperature of higher than 100° C. and lower than 400° C. The silver powder thus heat-treated has a maximum coefficient of thermal expansion of not greater than 1.5% at a temperature of 50° C. to 800° C., and has no heating peak when the silver powder is heated from 50° C. to 800° C. The silver powder has an ignition loss of not greater than 1.0% when the silver powder is ignited until the weight of the silver powder is constant at 800° C. The silver powder has a tap density of not less than 2 g/cm3 and a BET specific surface area of not greater than 5 m2/g.
    Type: Grant
    Filed: November 21, 2005
    Date of Patent: October 9, 2012
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Takatoshi Fujino, Kozo Ogi
  • Publication number: 20120219453
    Abstract: After a reducing agent is added to a water reaction system containing silver ions to deposit silver particles by reduction, the silver particles are dried to obtain a silver powder which is heat-treated at a temperature of higher than 100° C., and lower than 400° C. The silver powder thus heat-treated has a maximum coefficient of thermal expansion of not greater than 1.5% at a temperature of 50° C. to 800° C., and has no heating peak when the silver powder is heated from 50° C. to 800° C. The silver powder has an ignition loss of not greater than 1.0% when the silver powder is ignited until the weight of the silver powder is constant at 800° C. The silver powder has a tap density of not less than 2 g/cm3 and a BET specific surface area of not greater than 5 m2/g.
    Type: Application
    Filed: May 10, 2012
    Publication date: August 30, 2012
    Applicant: DOWA MINING CO., LTD.
    Inventors: Takatoshi Fujino, Kozo Ogi
  • Patent number: 7820138
    Abstract: At least one basic precipitant selected from the group consisting of NaOH, KOH, NH4OH, NH3, NH4HCO3 and (NH4)2CO3 is added to an indium salt solution, which contains 0.1 to 3 M of indium, in an adding time of not longer than 24 hours, while the solution is maintained at a temperature of 5 to 95° C. until the equivalent of the basic precipitant reaches an equivalent of 0.5 to 3. Then, a precipitate obtained from the solution by a solid-liquid separation is dried and calcined at a temperature of 570 to 780° C. in an non-oxidizing atmosphere which contains ammonia gas and water vapor.
    Type: Grant
    Filed: March 15, 2006
    Date of Patent: October 26, 2010
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Makoto Watanabe, Tatsumi Inamura, Yoshio Moteki
  • Patent number: 7722728
    Abstract: In a heat treatment method for supplying transforming gas and enriched gas inside a furnace and heat treating a workpiece inside the furnace, feedback control of carbon potential is performed by operating a supply flow rate of the enriched gas based on carbon potential inside the furnace, the feedback control is stopped before an opening of the furnace is opened and supply flow rates of the transforming gas and the enriched gas are increased from supply flow rates thereof immediately before the feedback control is stopped; and the supply flow rate of the transforming gas is returned to the supply flow rate thereof immediately before the feedback control is stopped and the feedback control is resumed after the opening of the furnace is closed.
    Type: Grant
    Filed: March 29, 2006
    Date of Patent: May 25, 2010
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Takanori Tsuge, Koji Abe
  • Patent number: 7651785
    Abstract: There is provided a tin-plated product which has a small deterioration of contact resistance with age, an excellent wear resistance and a low coefficient of friction. A coating of a composite material, which contains 0.1 to 1.0 wt % of carbon particles dispersed in a tin layer and which has a thickness of 0.5 to 10.0 ?m, preferably 1.0 to 5.0 ?m, is formed as the outermost layer of a substrate. Thus, the coefficient of dynamic friction between the tin-plated products of the same kind is 0.20 or less, and the coefficient of dynamic friction between the tin-plated product and a reflow tin-plated product is 0.20 or less, while the contact resistance is 1 m? or less.
    Type: Grant
    Filed: September 26, 2005
    Date of Patent: January 26, 2010
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Hirofumi Takei, Hiroshi Miyazawa, Kentaro Asai
  • Patent number: 7641817
    Abstract: There is provided a method for producing a silver powder having excellent dispersibility and capable of forming a paste which do not form suspended matters by phase separation and which is printed on a substrate to form a film having a uniform thickness. In this method, an alkali or a complexing agent is added to an aqueous silver salt containing solution to form a silver oxide containing slurry or an aqueous silver complex salt containing solution. After or before silver particles are deposited by reduction by adding a reducing agent to the silver oxide containing slurry or aqueous silver complex salt containing solution while stirring it, at least one chelating agent selected from the group consisting of compounds having an azole structure, dicarboxylic acids, hydroxy carboxylic acids and salts thereof is added to a silver power containing slurry solution as a dispersing agent.
    Type: Grant
    Filed: January 28, 2005
    Date of Patent: January 5, 2010
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Hiroshi Matsushima, Kozo Ogi
  • Patent number: 7585588
    Abstract: A material for the positive electrode of a silver oxide battery is provided that increases the discharge capacity of the battery. The positive electrode material is a conductive composite oxide represented by the general formula AgxNiyO2, in which X/Y is greater than 1 and does not exceed 1.9, and by the general formula AgxNiyMzO2, in which M represents at least one of Cu and Bi, X/(Y+Z) is greater than 1 and does not exceed 1.9, and Z does not exceed 0.4. These conductive oxides contain almost no free Ag2O and have a crystal structure similar to that of AgNiO2. As a result, the excess Ag—Ni oxide is conductive and has a high discharge capacity.
    Type: Grant
    Filed: December 23, 2005
    Date of Patent: September 8, 2009
    Assignee: Dowa Mining Co., Ltd.
    Inventor: Koji Tanoue
  • Patent number: 7575643
    Abstract: The invention provides a carburization treatment method in which the carburization treatment is conducted under a condition where an atmosphere within the furnace is maintained at a high carbon potential which is slightly blow a carbon solid solubility. Preferably, the internal pressure within the furnace is kept at 0.1 to 101 kPa, the hydrocarbon gas is one, two or more than two kinds of gases selected from the group consisting of C3H8, C3H6, C4H10, C2H2, C2H4, C2H6 and CH4, while the oxidative gas is an air, an O2 gas, or CO2 gas.
    Type: Grant
    Filed: March 28, 2002
    Date of Patent: August 18, 2009
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Hisashi Ebihara, Jun Takahashi, Fumitaka Abukawa, Keiji Yokose, Hidetoshi Juryozawa
  • Patent number: 7514022
    Abstract: There is provided a composite plated product which has a large content of carbon and a large quantity of carbon particles on the surface thereof and which has an excellent wear resistance, by sufficiently dispersing carbon particles in a silver plating solution without using any additives such as dispersing agents and without coating the surface of carbon particles. A wet oxidation treatment for carbon particles is carried out by adding an oxidizing agent to water in which the carbon particles are suspended, and the carbon particles treated by the wet oxidation treatment are added to a cyanide containing silver plating solution for electroplating a substrate to form a coating of a composite material, which contains the carbon particles in a silver layer, on the substrate.
    Type: Grant
    Filed: June 21, 2005
    Date of Patent: April 7, 2009
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Hiroshi Miyazawa, Akito Inoue
  • Patent number: 7481698
    Abstract: A surface grinding machine for a sintered rare earth magnetic alloy wafer comprises a pair of disk-shaped grindstones that face each other across a prescribed gap to be rotatable in opposite directions about their center axes. The grinding surfaces of the pair of grindstones and the center axe inclination of one grinding stone are configured to form a planar grinding region A wherein a portion of both of the grinding surfaces of the pair of grindstones lie parallel with a constant intervening gap therebetween. Other portions of the grinding surfaces of the grindstones constitute a wedge-like opening region B that becomes more narrow toward the planar grinding surface A. A feeder to feed the wafers from the wedge-like opening region B toward the planar grinding region A is provided in order to grind both surfaces of the wafers at the planar grinding.
    Type: Grant
    Filed: August 17, 2007
    Date of Patent: January 27, 2009
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Kiyoshi Yamada, Hirofumi Takei, Masami Kamada, Toshinori Eba
  • Publication number: 20090017333
    Abstract: Heat treatment is conducted at a predetermined temperature of not less than 1250° C. on an underlying substrate obtained by epitaxially forming a first group-III nitride crystal on a predetermined base as an underlying layer. Three-dimensional fine irregularities resulting from crystalline islands are created on the surface of the underlying layer. A second group-III nitride crystal is epitaxially formed on the underlying substrate as a crystal layer. There are a great many fine voids interposed at the interface between the crystal layer and underlying substrate. The presence of such voids suppresses propagation of dislocations from the underlying substrate, which reduces the dislocation density in the crystal layer. As a result, the crystal layer of good crystal quality can be obtained.
    Type: Application
    Filed: September 19, 2008
    Publication date: January 15, 2009
    Applicants: NGK Insulators, Ltd., Dowa Mining Co., Ltd.
    Inventor: Tomohiko SHIBATA
  • Patent number: 7462301
    Abstract: There is provided a method for producing a silver powder having excellent dispersibility and capable of forming a paste which do not form suspended matters by phase separation and which is printed on a substrate to form a film having a uniform thickness. In this method, an alkali or a complexing agent is added to an aqueous silver salt containing solution to form a silver oxide containing slurry or an aqueous silver complex salt containing solution. After or before silver particles are deposited by reduction by adding a reducing agent to the silver oxide containing slurry or aqueous silver complex salt containing solution while stirring it, at least one chelating agent selected from the group consisting of compounds having an azole structure, dicarboxylic acids, hydroxy carboxylic acids and salts thereof is added to a silver power containing slurry solution as a dispersing agent.
    Type: Grant
    Filed: April 17, 2007
    Date of Patent: December 9, 2008
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Hiroshi Matsushima, Kozo Ogi
  • Patent number: 7445672
    Abstract: Heat treatment is conducted at a predetermined temperature of not less than 1250° C. on an underlying substrate obtained by epitaxially forming a first group-III nitride crystal on a predetermined base as an underlying layer. Three-dimensional fine irregularities resulting from crystalline islands are created on the surface of the underlying layer. A second group-III nitride crystal is epitaxially formed on the underlying substrate as a crystal layer. There are a great many fine voids interposed at the interface between the crystal layer and underlying substrate. The presence of such voids suppresses propagation of dislocations from the underlying substrate, which reduces the dislocation density in the crystal layer. As a result, the crystal layer of good crystal quality can be obtained.
    Type: Grant
    Filed: August 14, 2006
    Date of Patent: November 4, 2008
    Assignees: NGK Insulators, Ltd., Dowa Mining Co., Ltd.
    Inventor: Tomohiko Shibata
  • Publication number: 20080230515
    Abstract: The present invention provides a method of forming a circuit pattern on an integrally bonded member, the method not requiring a correction step of a laminate film or a resist film which has been necessary at the time of wet treatment of the integrally bonded member. After a circuit pattern forming metal plate is bonded on a part of a ceramic substrate so as to expose an outer peripheral edge portion of the ceramic substrate in an integrally bonded member, the integrally bonded member is set on a treating apparatus while being covered with a masking member having a window portion from which the circuit pattern forming metal plate of the integrally bonded member is exposed.
    Type: Application
    Filed: May 19, 2008
    Publication date: September 25, 2008
    Applicant: DOWA MINING CO.,LTD
    Inventors: Ken Iyoda, Makoto Namioka, Hideyo Osanai, Susumu Shimada
  • Patent number: 7393596
    Abstract: When an aluminum plate is bonded directly to a ceramic substrate by cooling and solidifying molten aluminum which is injected into a mold so as to contact the ceramic substrate arranged in the mold, an additive, such as a TiB alloy, Ca or Sr, for decreasing the grain size of the aluminum plate to 10 mm or less while preventing the drop in thermal conductivity of the aluminum plate from the thermal conductivity of a pure aluminum plate from exceeding 20% of the thermal conductivity of the pure aluminum plate is added to the molten aluminum. When an aluminum alloy plate of an aluminum-silicon alloy is bonded directly to a ceramic substrate by cooling and solidifying a molten aluminum-silicon alloy which is injected into a mold so as to contact the ceramic substrate arranged in the mold, an aluminum-silicon alloy containing 0.1 to 1.5 wt % of silicon and 0.03 to 0.10 wt % of boron is injected into the mold.
    Type: Grant
    Filed: September 22, 2006
    Date of Patent: July 1, 2008
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Hideyo Osanai, Satoru Ideguchi
  • Patent number: 7393473
    Abstract: There is provided a composite plated product wherein a coating of a composite material containing carbon particles in a silver layer is formed on a substrate, the composite plated product having a large content of carbon and a large quantity of carbon particles on the surface thereof and having a low coefficient of friction and an excellent wear resistance. Carbon particles treated by an oxidation treatment and a silver matrix orientation adjusting agent are added to a silver plating solution for electroplating a substrate to adjust the orientation of a silver matrix to form a coating of a composite material, which contains the carbon particles in a silver layer, on the substrate.
    Type: Grant
    Filed: July 5, 2006
    Date of Patent: July 1, 2008
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Hiroshi Miyazawa, Reki Yonezawa
  • Patent number: 7394024
    Abstract: An oxide superconductor current lead in which generation of Joule heat at joint portions with a system side conductor and a power supply side conductor is reduced with use of an oxide superconductor with less heat penetration into a super conducting equipment system is provided.
    Type: Grant
    Filed: February 5, 2004
    Date of Patent: July 1, 2008
    Assignees: Dowa Mining Co., Ltd., Chubu Electric Power Co., Inc.
    Inventors: Shuichi Kohayashi, Kazuyuki Uemura, Shigeo Nagaya, Naoji Kashima
  • Patent number: 7387741
    Abstract: The present invention provides a method of forming a circuit pattern on an integrally bonded member, the method not requiring a correction step of a laminate film or a resist film which has been necessary at the time of wet treatment of the integrally bonded member. After a circuit pattern forming metal plate 13 is bonded on a part of a ceramic substrate 12 so as to expose an outer peripheral edge portion of the ceramic substrate 12 in an integrally bonded member 10, the integrally bonded member 10 is set on a treating apparatus 30 while being covered with a masking member 20 having a window portion 22 from which the circuit pattern forming metal plate 13 of the integrally bonded member 10 is exposed.
    Type: Grant
    Filed: March 27, 2003
    Date of Patent: June 17, 2008
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Ken Iyoda, Makoto Namioka, Hideyo Osanai, Susumu Shimada
  • Patent number: 7368665
    Abstract: A circuit board containing a metal-insulator composite member including an insulator substrate and a metal layer having a pattern, the composite member having an area where the spacing between a lower part of adjacent elements of the pattern on the metal layer which is in contact with the insulator is not greater than the thickness of the metal layer. Also a power module containing such circuit board.
    Type: Grant
    Filed: November 9, 2005
    Date of Patent: May 6, 2008
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Masahiro Hara, Hideyo Osanai