Particulate Material Patents (Class 148/105)
-
Patent number: 4469507Abstract: Disclosed herein is a process for producing ferromagnetic iron powder, which process comprises adding and mixing zinc borate with .alpha.-FeOOH or .alpha.-Fe.sub.2 O.sub.3 without dissolving the former, heating the thus-obtained mixture to 350.degree. C. or higher in a non-reducing atmosphere and then reducing the thus-heated mixture.Type: GrantFiled: January 24, 1983Date of Patent: September 4, 1984Assignee: Mitsui Toatsu Chemicals, IncorporatedInventors: Haruo Sekiguchi, Kazufuyu Sudoh, Sadao Kobayashi, Nobuhiro Fukuda
-
Patent number: 4469506Abstract: Disclosed herein is a process for producing ferromagnetic iron powder, which process comprises adding and mixing boron oxide or a borate with .alpha.-FeOOH or .alpha.-Fe.sub.2 O.sub.3 without dissolving the former, heating the thus-obtained mixture to 350.degree. C. or higher in a non-reducing atmosphere and then reducing the thus-heated mixture.Type: GrantFiled: January 24, 1983Date of Patent: September 4, 1984Assignee: Mitsui Toatsu Chemicals, IncorporatedInventors: Haruo Sekiguchi, Kimiteru Tagawa, Kazushi Ohshima, Nobuhiro Fukuda
-
Patent number: 4464196Abstract: Acicular ferromagnetic metal particles consisting essentially of iron and having coercive forces greater than 1300 oersteds when the surface areas of the particles are not greater than 45 m.sup.2 /gram are described. The particles are obtained by reducing a hydrothermally produced .alpha.-Fe.sub.2 O.sub.3 with a gaseous reducing agent at a temperature of about 300.degree. to 400.degree. C.Type: GrantFiled: August 24, 1983Date of Patent: August 7, 1984Assignee: Hercules IncorporatedInventor: James E. French
-
Patent number: 4456475Abstract: A process for preparing ferromagnetic particles comprising metallic iron as the major component by oxidizing Fe(OH).sub.2 in an aqueous medium adjusted to a pH of not less than 11 with gaseous oxygen to produce particles of .alpha.-FeOOH, optionally followed by dehydration of the .alpha.-FeOOH particles under heating to produce particles of .alpha.-Fe.sub.2 O.sub.3, and reducing the .alpha.-FeOOH or .alpha.-Fe.sub.2 O.sub.3 particles under heating, characterized in that (1) the aqueous medium at the oxidation step comprises at least one metal compound chosen from compounds of alkaline earth metals, zinc and aluminum and (2) the coating of a silicon compound is applied to the .alpha.-FeOOH or .alpha.-Fe.sub.2 O.sub.3 particles before the reduction step, whereby the ferromagnetic particles of metallic iron having enhanced magnetic characteristics are obtained.Type: GrantFiled: July 25, 1983Date of Patent: June 26, 1984Assignee: Hitachi Maxell, Ltd.Inventors: Shigeo Hirai, Toshinobu Sueyoshi, Masahiro Amemiya
-
Patent number: 4439796Abstract: A magnetic recording medium is described having formed on a non-magnetic base at least two magnetic layers, each of the magnetic layers comprising ferromagnetic particles dispersed in a binder, wherein the ferromagnetic particles in the outermost magnetic layer are substantially cubic particles and have a side length of 0.3.mu. or less, and the ferromagnetic particles in an underlying magnetic layer are acicular particles.Type: GrantFiled: December 9, 1981Date of Patent: March 27, 1984Assignee: Fuji Photo Film Co., Ltd.Inventors: Tatsuji Kitamoto, Goro Akashi
-
Patent number: 4439795Abstract: A magnetic recording medium is described having formed on a non-magnetic base at least two magnetic layers, each of the magnetic layers comprising ferromagnetic particles dispersed in a binder, wherein the ferromagnetic particles in the outermost layer have an average length of 0.3.mu. or less and a length to width ratio of greater than 1/1 but not greater than 3/1, and the ferromagnetic particles in an underlying layer have a length to width ratio of more than 3/1.Type: GrantFiled: December 9, 1981Date of Patent: March 27, 1984Assignee: Fuji Photo Film Co., Ltd.Inventors: Tatsuji Kitamoto, Goro Akashi
-
Patent number: 4439231Abstract: Acicular ferromagnetic metal particles consisting essentially of iron are prepared by a process wherein acicular iron(III) oxide hydroxide provided with a shape-stabilizing surface coating, or iron(III) oxide obtained therefrom by dehydration, is reduced by means of a decomposable organic compound and hydrogen.Type: GrantFiled: July 28, 1983Date of Patent: March 27, 1984Assignee: BASF AktiengesellschaftInventors: Werner Steck, Peter Rudolf, Wilhelm Sarnecki, Werner Loeser, Jenoe Kovacs, Helmut Jakusch
-
Patent number: 4437881Abstract: Acicular ferromagnetic alloy particles doped with silicon, chromium and nickel and optionally magnesium and a process for producing said particles comprising heating at 300.degree. to 500.degree. C. under reducing atmosphere acicular particles of .alpha.-iron(III) oxide hydroxide doped with silicon, chromium and nickel and optionally magnesium or acicular particles of .alpha.-ferric oxide doped with silicon, chromium and nickel and optionally magnesium obtained by dehydrating the acicular particles of .alpha.-iron(III) oxide hydroxide doped with silicon, chromium and nickel and optionally magnesium are disclosed herein.Type: GrantFiled: July 14, 1983Date of Patent: March 20, 1984Assignee: Toda Kogyo Corp.Inventors: Akio Mishima, Yoshiro Okuda, Tosiharu Harada, Akira Mukaizaka, Tomoyuki Imai
-
Patent number: 4406694Abstract: A process for producing an acicular ferromagnetic alloy particles mainly containing iron and magnesium, which comprises preparing a suspension of iron(II) hydroxide and water-soluble magnesium salt, the suspension having a pH value of at least 11 and containing the magnesium salt in an amount of 0.5 to 20.0 atomic % based on the amount of the iron(II) hydroxide in the suspension and calculated as the ratio of Mg to Fe(II), oxidizing the suspension with an oxygen-containing gas to form an acicular particles of iron(III) oxide hydroxide substituted with magnesium, forming coats of phosphorus compound and subsequent silicon compound on the acicular particles, heating the resultant particle at 500.degree. to 900.degree. C. under a non-reducing atmosphere and then reheating the particle thus treated at 350.degree. to 600.degree. C. under reducing atmosphere.Type: GrantFiled: July 23, 1981Date of Patent: September 27, 1983Assignee: Toda Kogyo Corp.Inventors: Akio Mishima, Yosiro Okuda, Tosiharu Harada, Akira Mukaizaka
-
Patent number: 4401462Abstract: A metallic magnetic powder as fine metallic particles is produced by adsorbing zinc ion on iron oxyhydroxide in a alkaline bath with heating during or after the adsorption and then reducing it.Type: GrantFiled: April 1, 1981Date of Patent: August 30, 1983Assignee: TDK Electronics Co., Ltd.Inventors: Akio Watanabe, Tosiaki Ide, Tatsuo Uehori
-
Patent number: 4394160Abstract: Magnetic powders for use in the manufacture of magnetic recording media are produced by a borohydride process in which aqueous solutions of ferrous sulfate and sodium borohydride are mixed in a magnetic field. The coercive force of the magnetic powder produced as a result of this method is controlled by controlling the temperature of the reactant solutions prior to mixing thereof.Type: GrantFiled: December 3, 1979Date of Patent: July 19, 1983Assignee: Sperry CorporationInventors: Walter O. Freitag, Victor V. Suchodolski
-
Patent number: 4390361Abstract: A process for preparing ferromagnetic iron particles comprising metallic iron as the major component by reduction of particles of an iron oxide under heating, characterized in that the iron oxide particles are provided with a first coating layer containing at least one metal compound chosen from compounds of aluminum, zinc and alkaline earth metals at the surfaces and a second coating layer containing at least one silicon compound thereon before the reduction, whereby the coated particles are prevented from sintering and breaking upon reduction so as to give ferromagnetic particles of metallic iron having excellent magnetic characteristics.Type: GrantFiled: June 11, 1981Date of Patent: June 28, 1983Assignee: Hitachi Maxell, Ltd.Inventors: Toshinobu Sueyoshi, Shigeo Hirai, Masahiro Amemiya
-
Patent number: 4384892Abstract: The magnetic characteristics of magnetic powder consisting mainly of iron are improved by pre-treating the starting material from which the magnetic powder is prepared by reductions, with an aqueous solution and/or suspension of one member selected from the group consisting of zinc, chromium and copper compounds and mixtures thereof.Type: GrantFiled: February 11, 1981Date of Patent: May 24, 1983Assignee: Kanto Denka Kogyo Co., Ltd.Inventors: Shintaro Suzuki, Sadao Iizuka, Yoshimi Moriya, Yuichi Omote
-
Patent number: 4378240Abstract: A process for the preparation of acicular ferromagnetic metal particles, consisting essentially of iron, by reducing acicular iron oxides and/or iron oxide hydroxides, which are either pure or are modified with conventional foreign metal ions, by means of a gaseous reducing agent in a fluidized bed furnace in which a stirrer is provided immediately above the fluidizing grid.Type: GrantFiled: May 28, 1981Date of Patent: March 29, 1983Assignee: BASF AktiengesellschaftInventors: Hansjoerg Siegle, Hans H. Reich, Horst Autzen, Werner Steck, Werner Loeser, Eckhard Hetzel, Manfred Ohlinger
-
Patent number: 4369076Abstract: A process for producing a magnetic metal powder having improved oxidation resistance and magnetic properties, which comprises wetting a magnetic metal powder in an atmosphere of a non-oxidizing gas with a solution of a boron trialkoxide in a solvent being inert to the magnetic metal powder and capable of dissolving the boron trialkoxide; and thereafter evaporating off the solvent.Type: GrantFiled: June 18, 1981Date of Patent: January 18, 1983Assignees: Dainippon Ink & Chemicals Inc., Kawamura Institute of Chemical ResearchInventors: Tesshu Miyahara, Yoshi Arai, Kazuo Kimura
-
Patent number: 4360377Abstract: Ferromagnetic metal particles, consisting essentially of iron and comprising a core, containing not less than 85% by weight of metallic iron, and an iron oxide plus chromium oxide surface layer surrounding this core, which layer additionally contains one or more elements selected from the group comprising zinc, phosphorus in the form of phosphate, aluminum, calcium, strontium, barium, cadmium, lead, cobalt and nickel in a total amount of not more than 9.5% by weight, based on the total amount of the metal particles, and a process for the production of such particles.Type: GrantFiled: June 29, 1981Date of Patent: November 23, 1982Assignee: BASF AktiengesellschaftInventors: Werner Steck, Hermann Roller, Wilhelm Sarnecki, Werner Balz
-
Patent number: 4360382Abstract: A number of extremely thin magnetic plates advantageously used for head cores are formed at one time by subsequent application of pressing, sintering, peripheral cutting and separating to a green multilayer construction which includes alternately superimposed metallic powder and parting agent layers, the former resulting in the magnetic plates. High yield is obtained with trouble-free process while making the best use of hard-to-work materials such as Fe-Al-Si type alloys which in general have excellent magnetic properties.Type: GrantFiled: August 9, 1979Date of Patent: November 23, 1982Assignee: Nippon Gakki Seizo Kabushiki KaishaInventors: Kenzaburo Iijima, Kazuo Kurahashi, Toshiharu Hoshi
-
Patent number: 4347291Abstract: A magnetic recording medium is produced by forming an alkaline aqueous slurry of an acicular hydrated iron oxide or an acicular iron oxide as a starting material; adding a water soluble silicate to said slurry; treating it by a hydrothermal reaction in a closed reactor as an autoclave at elevated temperature and pressure; dehydrating and drying said slurry to obtain a dry iron oxide containing SiO.sub.2 component; converting it into a magnetic metallic iron powder by a reduction in a reducing atmosphere as hydrogen atmosphere; and coating a magnetic composition obtained by mixing said magnetic metallic iron powder with a binder.Type: GrantFiled: November 20, 1980Date of Patent: August 31, 1982Assignee: TDK Electronics Co., Ltd.Inventor: Yasumichi Tokuoka
-
Patent number: 4344791Abstract: A process for the manufacture of acicular ferromagnetic iron particles by heating a goethite, provided with a shape-stabilizing surface coating, at 250.degree.-450.degree. C. in an atmosphere containing water vapor at a partial pressure of not less than 30 mbar, to give alpha-iron(III) oxide, and reducing this material with hydrogen at 275.degree.-425.degree. C., and the use of the iron particles thus obtained as magnetic material in the production of magnetic recording media.Type: GrantFiled: July 31, 1980Date of Patent: August 17, 1982Assignee: BASF AktiengesellschaftInventors: Werner Steck, Wilhelm Sarnecki, Laszlo Marosi, Manfred Ohlinger, Werner Loeser
-
Patent number: 4342589Abstract: Disclosed is a process for preparing fine needle-like, ferromagnetic iron compound particles for use in magnetic recording in which needle-like iron oxyhydroxide fine particles prepared by simultaneously co-precipitating or cladding iron compound particles with an element of group II of the Periodic Table and manganese at atomic weight ratios of the element of group II of the Periodic Table and manganese to iron of from 0.001/100 to 10/100 and 0.005/100 to 10/100 respectively are reduced and/or oxidized under heating.Type: GrantFiled: January 30, 1981Date of Patent: August 3, 1982Assignee: Mitsui Toatsu Chemicals, Inc.Inventors: Kazushi Ohshima, Mitsuro Matsunaga, Haruo Sekiguchi, Kazuhiro Imaoka, Fujio Hayashi
-
Patent number: 4331489Abstract: A magnetic powder is produced by mixing an aqueous solution of a metal salt with an aqueous solution of a reducing agent such as sodium boron hydride in a magnetic field to reduce said metal salt to continuously form a magnetic powder and heat-treating said magnetic powder in a non-oxidative atmosphere. The aqueous solution of a metal salt is mixed with said aqueous solution of a reducing agent in a magnetic field to continuously discharge a reaction mixture containing a magnetic powder having pH of 2.5 or lower from a reactor and said reaction mixture containing said magnetic powder is immediately continuously washed and filtered and said magnetic powder is heat-treated in said non-oxidative atmosphere.Type: GrantFiled: November 6, 1980Date of Patent: May 25, 1982Assignee: TDK Electronics Co., Ltd.Inventors: Tatsuo Uehori, Akio Watanabe, Tosiaki Ide
-
Patent number: 4318735Abstract: Fine magnetic particles with high saturation magnetization (over 140 emu/g) as well as high stability against oxidation in air, are produced by a process which comprises the first stage of oxidizing the surfaces of metallic particles consisting mainly of iron in an atmosphere containing both H.sub.2 O and H.sub.2 gases at an oxidizing temperature below 900.degree. C., and the second stage of further oxidizing the surfaces of the particles produced at the first stage in an atmosphere containing O.sub.2 gas.Type: GrantFiled: June 6, 1980Date of Patent: March 9, 1982Assignee: Toda Kogyo Corp.Inventors: Akio Mishima, Hiroyuki Kondo, Akira Mukaizaka
-
Patent number: 4318757Abstract: Ferromagnetic metal particles of high quality are produced by a process which comprises heat-treating starting material particles selected from the group consisting of the particles of ferromagnetic metals, ferromagnetic alloys, and oxides and hydroxides of ferromagnetic metals, in a reducing atmosphere at a temperature required for converting the material particles into ferromagnetic metal particles of improved magnetic properties. Electrostatic charges are imparted to the material particles during the heat treatment, whereby aggregation of material particles is hindered during the treatment.Type: GrantFiled: May 5, 1980Date of Patent: March 9, 1982Assignee: TDK Electronics Co., Ltd.Inventors: Rioichi Horimoto, Riyuuzou Seike
-
Patent number: 4309459Abstract: An SiO.sub.2 coated iron oxide powder used for the preparation of an acicular metallic iron powder or an acicular magnetic iron oxide powder, is produced by forming a slurry of hydrated iron oxide as a starting material or a iron oxide powder having pH of 8 to 14; admixing a water soluble silicate at a ratio of 0.1 to 10 mol % as SiO.sub.2 based on Fe; hydrothermally reacting said mixed slurry at 100.degree. to 250.degree. C. for 5 minutes or longer in a closed reactor, and washing, filtering and drying the product.Type: GrantFiled: November 25, 1980Date of Patent: January 5, 1982Assignee: TDK Electronics Co., Ltd.Inventor: Yasumichi Tokuoka
-
Patent number: 4306921Abstract: The magnetic characteristics of magnetic powder consisting mainly of iron are improved by pre-treating the starting material from which the magnetic powder is prepared by reduction, with an aqueous solution and/or suspension of one member selected from the group consisting of cobalt, nickel, manganese and antimony compounds and mixtures thereof.Type: GrantFiled: March 7, 1979Date of Patent: December 22, 1981Assignee: Kanto Denka Kogyo Co., Ltd.Inventors: Shintaro Suzuki, Sadao Iizuka, Yoshimi Moriya
-
Patent number: 4305752Abstract: In the process for preparing a magnetically stable powder comprising the steps of reducing an iron oxide precursor with a gaseous reduction agent and stabilizing the metallic powder thus produced, the improvement which comprises coating said iron oxide precursor with an antimony compound at a level of up to about 7 weight percent antimony based on the weight of the iron oxide content of the precursor and precipitating tin hydroxides or oxyhydroxides at a level of from about 0.5 to about 8.0 weight percent tin based on the weight of the iron oxide content of the precursor onto the antimony coated iron oxide precursor prior to said reduction.Type: GrantFiled: June 5, 1980Date of Patent: December 15, 1981Assignee: Pfizer Inc.Inventor: Louis J. Dizikes
-
Patent number: 4305753Abstract: Described is an improved process for producing acicular ferromagnetic metallic particles by the reduction of acicular particles of iron oxide or iron oxide hydrate with a gaseous reducing agent. More specifically, the process concerns the improvement wherein the iron oxide or iron oxide hydrate particles are treated with a specified amount of a phosphorus compound and a compound of cobalt, nickel and/or copper prior to the reduction step.Type: GrantFiled: July 31, 1980Date of Patent: December 15, 1981Assignee: Hercules IncorporatedInventor: James E. French
-
Patent number: 4295879Abstract: A process for the manufacture of acicular ferromagnetic iron particles by reducing an iron(III) oxide which carries a shape-stabilizing surface coating and has been produced by heating acicular iron(III) oxide hydroxide at 250.degree.-390.degree. C. in an atmosphere containing water vapor at a partial pressure of not less than 30 mbar, with hydrogen at 275.degree.-425.degree. C.Type: GrantFiled: July 31, 1980Date of Patent: October 20, 1981Assignee: BASF AktiengesellschaftInventors: Werner Steck, Wilhelm Sarnecki, Laszlo Marosi, Manfred Ohlinger, Horst Autzen
-
Patent number: 4290826Abstract: A process for producing cobalt-rare earth alloy powders suitable for forming into permanent magnets includes mixing cobalt powder particles having refractory oxide dispersoid powder particles fixed in the surfaces of the cobalt particles with particles of a rare earth element in a proportion corresponding to the composition of the alloy to be formed. The mixture is heated to cause the cobalt-dispersoid particles and the rare earth particles to form the desired alloy by diffusion with substantially no sintering.Type: GrantFiled: September 30, 1980Date of Patent: September 22, 1981Assignee: Sherritt Gordon Mines LimitedInventor: Maurice A. Clegg
-
Patent number: 4272285Abstract: In a process for producing a magnetic metal powder, a magnetic metal compound is reduced by wet reduction in a state mixed with a clay or is heat treated in the presence of a clay powder. Alternatively, a magnetic metal powder is prepared by reducing a magnetic metal powder by wet reduction or by reducing a magnetic metal compound in a state mixed with a clay by dry reduction, and then the resulting powder is heat treated in the presence of the clay powder. The clay is typically kaolin.Type: GrantFiled: July 11, 1980Date of Patent: June 9, 1981Assignee: TDK Electronics Co., Ltd.Inventor: Rioichi Horimoto
-
Patent number: 4260999Abstract: A semiconductor device and a method of manufacturing the same, wherein there are provided, on a semiconductor substrate of a first conductivity type, a first and a second epitaxial layer each having a second conductivity type opposite to the first conductivity type. A plurality of regions are defined in the entire area of the epitaxial layer by being isolated by means of an isolation layer of the first conductivity type which extends from the surface of the second epitaxial layer to the semiconductor substrate. Furthermore, a first buried layer of the second conductivity type is formed in each of the isolated regions in such a manner as to extend in the first epitaxial layer and semiconductor substrate so that a transistor can be formed on each first buried layer.Type: GrantFiled: April 6, 1979Date of Patent: April 7, 1981Assignee: Toko, Inc.Inventor: Fumio Yoshioka
-
Patent number: 4256484Abstract: In the process for preparing a magnetically stable, powder comprising the steps of reducing an iron oxide or iron oxide hydrate with a gaseous reduction agent and stabilizing the metallic powder thus produced, the improvement which comprises enhancing its reduction by coating said iron oxide or iron oxide hydrate with an antimony compound at a level of up to about 7 weight percent antimony based on the weight of the iron oxide prior to said reduction.Type: GrantFiled: July 30, 1979Date of Patent: March 17, 1981Assignee: Pfizer Inc.Inventor: Richard H. Rodrian
-
Patent number: 4253886Abstract: Corrosion resistant ferromagnetic metal powders in which a volatile corrosion inhibitor is adsorbed on at least a part of the surface of ferromagnetic metal powders having an average particle size of 1000 A or less are disclosed. A method of preparing the corrosion resistant ferromagnetic metal powders is also disclosed.Type: GrantFiled: August 8, 1977Date of Patent: March 3, 1981Assignee: Fuji Photo Film Co., Ltd.Inventors: Masashi Aonuma, Yasuo Tamai
-
Patent number: 4248907Abstract: A magnetic powder is prepared by dispersing iron oxide or iron oxide hydrate which can be coated or doped with at least one of cobalt, nickel, tin, titanium, bismuth, zinc or antimony or its compound, as the starting material into an aqueous solution of a water soluble resin and separating the powder and heating it in a reducing atmosphere to reduce it.Type: GrantFiled: July 25, 1979Date of Patent: February 3, 1981Assignee: TDK Electronics Company, LimitedInventors: Tatsuo Uehori, Ryouichi Horiboto
-
Patent number: 4246316Abstract: This invention relates to a magnetic recording medium comprising a non-magnetic support and magnetic layer provided thereon containing a ferromagnetic metal powder, the magnetic layer having a multilyaer structure consisting of a lower layer containing acicular grains obtained by dry process reduction and an upper layer containing chain-like grains obtained by wet process reduction, the upper layer being provided on the lower layer. This magnetic recording medium is particularly suitable for high density recording.Type: GrantFiled: March 17, 1978Date of Patent: January 20, 1981Assignee: Fuji Photo Film Co., Ltd.Inventors: Masashi Aonuma, Yasuo Tamai
-
Patent number: 4237506Abstract: An improved magnetic recording member of the disc type, the article of the invention is polymodal wherein one mode is formed of a first population of magnetic particles which have a coercivity differing by at least 200 oersteds from the coercivity of particles in another mode. These latter particles are, preferably, metallic magnetic particles oriented in a vertical direction and are in a thin layer over said first population of magnetic particles. This combination overcomes existing limitations on (a) disc products, and (b) the preferred metallic particles heretofore known.Type: GrantFiled: April 3, 1978Date of Patent: December 2, 1980Assignee: Graham Magnetics Inc.Inventor: William A. Manly
-
Patent number: 4236945Abstract: A phosphorus-iron powder is disclosed for use in the pressing and sintering of soft magnetic parts. This powder comprises a substantially phosphorous free iron powder blended with a sufficient quantity of ferrophosphorus powder having an average particle size of at least 10 micron and a phosphorus content of from 18 to 30%, to arrive at a phosphorus content for the mixture in a range of from about 0.40 to 1.25%. By pressing the blended mixture to a green density of at least 6.0 grams per cubic centimeter, and sintering the pressed mixture in a nonoxidizing atmosphere at a temperature of at least 1900.degree.F., the part linear shrinkage during sintering is less than 2%.Type: GrantFiled: November 27, 1978Date of Patent: December 2, 1980Assignee: Allegheny Ludlum Steel CorporationInventor: Orville W. Reen
-
Patent number: 4229234Abstract: A process, and the compositions produced thereby, wherein an element characterized as aluminum, silicon or chromium, notably aluminum, is alloyed in relatively small concentrations with iron, cobalt or nickel, notably iron or cobalt, or both, which have relatively high Curie temperatures. Small amounts of yttrium, hafnium, zirconium or lanthanium can also be added. Alloys of specified composition are formed into particles of selected size, and the particles then contacted in an atmosphere of controlled oxygen activity at elevated temperature over selected time periods. By treatment with a low oxygen-containing, or low moisture-containing gas an oxide of the alloying element is formed which diffuses to the surface of the particles to form a film. The addition of these elements to the base metal necessarily, and unavoidably reduces the Curie temperature of the metal.Type: GrantFiled: December 29, 1978Date of Patent: October 21, 1980Assignee: Exxon Research & Engineering Co.Inventors: Richard C. Krutenat, Chih-an Liu
-
Patent number: 4223085Abstract: Magnetically-responsive electrostatographic nickel carrier particles having semi-conductive and lower triboelectric charging properties are prepared by heat treating nickel particles in an ambient atmosphere as to provide the carrier particles with an oxide coating. More particularly, commercially available nickel particles are placed in a furnace and the particles are heat treated at a temperature of between about 600.degree. C. and about 1,000.degree. C. for a period of time of between about 5 and 10 minutes. When employed with finely-divided toner particles to develop electrostatic latent images in a magnetic-brush development apparatus, the treated carriers have been found to alleviate shorting problems and to provide developed images having lower background densities and higher resolution than prior carrier materials.Type: GrantFiled: April 5, 1976Date of Patent: September 16, 1980Assignee: Xerox CorporationInventors: Robert J. Hagenbach, Rudolph Forgensi, Stewart W. Volkers, Dennis F. Di Orazio
-
Patent number: 4222798Abstract: A method of manufacturing a ferromagnetic metal powder by continuously drying and subsequently heat treating a slurry of ferromagnetic metal powder formed by wet reduction, characterized in that a non-oxidizing gas is supplied in separate streams to the two processes, and the non-oxidizing gas used in the drying and heat treatment is treated and recovered through separate circuits for recycling to the corresponding processes of drying and heat treatment. The separate circuits for recycling the non-oxidizing gas, the conditions in the separate two circuits are made optimum and independently adjustable so that a ferromagnetic powder of good properties is obtained.Type: GrantFiled: March 13, 1979Date of Patent: September 16, 1980Assignee: TDK Electronics Company LimitedInventors: Minoru Yoda, Yasumichi Tokuoka
-
Patent number: 4221614Abstract: A method of manufacturing a ferromagnetic metal powder characterized by continuously drying a slurry of ferromagnetic metal powder formed by wet reduction, in a non-oxidizing gas atmosphere, and subsequently continuously heat-treating the dried ferromagnetic metal powder in a non-oxidizing gas atmosphere. The continuous method prevents the ferromagnetic metal powder from being exposed to excess oxygen to enhance the magnetic properties of the ferromagnetic metal powder. Also, the production efficiency is enhanced.Type: GrantFiled: March 13, 1979Date of Patent: September 9, 1980Assignee: TDK Electronics Co., Ltd.Inventors: Minoru Yoda, Yasumichi Tokuoka
-
Patent number: 4218507Abstract: Novel powders, and resinous compositions bearing said powders, characterized by excellent chemical stability, electrical conductivity, and energy-absorbing characteristics. These three characteristics can be utilized, alone or combination, in forming many novel articles including microwave shielding apparatus, magnetic recording media, explosives, and the like articles. The more advantageous powders are characterized by a very thin coating of an electrically conductive metal carbide, metal silicide, or metal boride upon the surface thereof, and a metal core.Type: GrantFiled: September 8, 1978Date of Patent: August 19, 1980Assignee: Graham Magnetics, Inc.Inventors: Robert J. Deffeyes, Grover L. Johnson
-
Patent number: 4214893Abstract: A method is provided for making a magnetic powder composed principally of cobalt from a mixture solution containing metal salts, such as cobalt salt, and the like, catalysts, such as palladium chloride, and the like, and reducing agents, such as sodium hypophosphite, and the like. Protein, such as albumin or hemoglobin, is added to the mixture solution to promote dispersion of cobalt particles therein. The magnetic powder thus obtained is suitable for use in the production of audio and video tapes.Type: GrantFiled: November 7, 1977Date of Patent: July 29, 1980Assignee: Nippon Columbia KabushikikaishaInventors: Kunihiro Tsuganezawa, Teruo Kobayashi, Shigehisa Harada, Yoichi Nishizawa, Tomoya Kusunose
-
Patent number: 4197118Abstract: The disclosure relates to a method of binder removal from a green body before sintering or the like wherein the green body is initially heated to a temperature above the flow point of the binder to liquify the binder and, at this elevated temperature, surrounded by a solvent for said binder in the vapor phase and at a temperature slightly above the melting point of the binder. The solvent vapor enters the green body slowly and dissolves the binder therein so that excessive stresses are not provided within the body due to binder expansion until binder-solvent substantially ceases to exude from the body. The body is then placed in a bath of the solvent, the solvent being maintained at a temperature above the flow point of the binder to remove remaining binder from the body.Type: GrantFiled: April 12, 1976Date of Patent: April 8, 1980Assignee: Parmatech CorporationInventor: Raymond E. Wiech, Jr.
-
Patent number: 4197347Abstract: A magnetic recording medium comprising a nonmagnetic support having thereon a magnetic recording layer of a ferromagnetic powder dispersed in a binder, wherein the ferromagnetic powder is a low vacuum evaporation process ferromagnetic metal powder subjected to a surface oxidation stabilizing processing and the low vacuum evaporation process ferromagnetic metal powder is one processed with an aqueous solution containing at least one anionic surface active agent.Type: GrantFiled: July 19, 1978Date of Patent: April 8, 1980Assignee: Fuji Photo Film Co., Ltd.Inventors: Hiroshi Ogawa, Yasuo Tamai, Matsuaki Nakamura
-
Patent number: 4178171Abstract: A process for the manufacture of acicular ferromagnetic iron particles by reducing acicular iron(III) oxide hydroxides which consist of pure synthetic lepidocrocite or a mixture of synthetic goethite and at least 70% by weight of synthetic lepidocrocite.The iron(III) oxide hydroxides used carry, on their surface, an alkaline earth metal cation and an anion of a monobasic, dibasic or tribasic aliphatic carboxylic acid of up to 6 carbon atoms or an organic compound containing at least two groups capable of chelating the alkaline earth metal cation, and are produced in such a way that they consist of at least 70 percent by weight of lepidocrocite and have a length-to-width ratio of not less than 15:1.Reduction of such iron(III) oxide hydroxides gives iron particles with pronounced shape anisotropy, which exhibit both good magnetic properties and a narrow field strength distribution.Type: GrantFiled: March 20, 1978Date of Patent: December 11, 1979Assignee: BASF AktiengesellschaftInventors: Werner Steck, Rudolf Brodt, Wilhelm Sarnecki, Helmut Jakusch, Manfred Ohlinger, Eberhard Koester
-
Patent number: 4177089Abstract: Magnetic particles and compacts formed therefrom for use as magnetic cores formed of a blend of iron particles and particles of sendust, with the particles containing a coating of an electrical insulator thereon. The particles are compacted and annealed in the practice of this invention to form magnetic cores.Type: GrantFiled: April 24, 1978Date of Patent: December 4, 1979Assignee: The Arnold Engineering CompanyInventor: Billye Bankson
-
Patent number: 4165232Abstract: A process for the manufacture of acicular ferromagnetic metal particles which essentially consist of iron and carry, on their surface, from 0.02 to 0.6% by weight of boron in the form of a borate, by reducing an acicular iron oxide with a gaseous reducing agent at from 250.degree. to 500.degree. C., wherein a compound selected from the group comprising boron oxyacids and their inorganic salts is precipitated on the said iron oxide before reduction.Type: GrantFiled: September 15, 1978Date of Patent: August 21, 1979Assignee: BASF AktiengesellschaftInventors: Christof Jaeckh, Werner Steck, Rudolf Brodt, Manfred Ohlinger, Werner Loeser, Eberhard Koester
-
Patent number: 4158561Abstract: A method for preparing oxide coated microlaminations characterized by heating microlamination particles at a temperature of about 1375.degree. in an atmosphere having a dew point of 55.degree. to 85.degree. F. and an air-to-natural gas ratio of from about 10.5:1 to about 8:1 for a time sufficient to decarburize the particles to less than 0.005% carbon and to form on the particle surfaces an oxide coating having a thickness of from about 0.01 to about 0.10 mils.Type: GrantFiled: April 14, 1978Date of Patent: June 19, 1979Assignee: Westinghouse Electric Corp.Inventors: Norman M. Pavlik, John Sefko
-
Patent number: 4158582Abstract: A method of making pressed magnetic core components having a low core loss property for use in electrical apparatus characterized by reannealing and repressing said components after initial annealing and pressing.Type: GrantFiled: April 14, 1978Date of Patent: June 19, 1979Assignee: Westinghouse Electric Corp.Inventor: Robert F. Krause