EP0043921B1 - Particules métalliques ferromagnétiques constituées essentiellement de fer ayant une couche de revêtement superficiel, procédé pour leur préparation ainsi que leur utilisation pour la fabrication des supports d'enregistrement magnétiques - Google Patents

Particules métalliques ferromagnétiques constituées essentiellement de fer ayant une couche de revêtement superficiel, procédé pour leur préparation ainsi que leur utilisation pour la fabrication des supports d'enregistrement magnétiques Download PDF

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Publication number
EP0043921B1
EP0043921B1 EP81104590A EP81104590A EP0043921B1 EP 0043921 B1 EP0043921 B1 EP 0043921B1 EP 81104590 A EP81104590 A EP 81104590A EP 81104590 A EP81104590 A EP 81104590A EP 0043921 B1 EP0043921 B1 EP 0043921B1
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Prior art keywords
metal particles
iron
chromium
ions
metal
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Expired
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EP81104590A
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German (de)
English (en)
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EP0043921A1 (fr
Inventor
Werner Dr. Steck
Hermann Roller
Wilhelm Dr. Sarnecki
Werner Dr. Balz
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BASF SE
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BASF SE
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/16—Making metallic powder or suspensions thereof using chemical processes
    • B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
    • B22F9/24—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from liquid metal compounds, e.g. solutions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/16—Metallic particles coated with a non-metal
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/06—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder
    • H01F1/061—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder with a protective layer
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/09—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials mixtures of metallic and non-metallic particles; metallic particles having oxide skin
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12181—Composite powder [e.g., coated, etc.]

Definitions

  • the invention relates to ferromagnetic metal particles consisting essentially of iron with a surface coating of metal oxides in which other metal ions and / or phosphate ions are additionally bound in addition to chromium, iron and oxygen, a process for their production and their use for the production of magnetic recording media.
  • the surface protection of the finely divided ferromagnetic metal particles was attempted, as in JP-OS 42 990/76.
  • ferromagnetic metal particles consisting essentially of iron from a core comprising at least 85% by weight of metallic iron and an iron and chromium oxide surface layer enveloping this core if the metal particles in the Surface layer in addition to iron, oxygen and 1 to 9 wt .-% chromium, based on the total amount of the metal particle, additionally at least one element not derived from the core selected from the group of 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 particle.
  • the invention also relates to a method for producing the ferromagnetic metal particles according to the invention.
  • the ferromagnetic metal particles according to the invention accordingly consist of a core which consists of at least 85% by weight of metallic iron and as pyrophoric particles usually by reduction of ⁇ - or ⁇ -iron (III) oxide hydroxide, the mixture or dewatering products thereof, which expediently occurs the reduction, as described for example in DE-OS 2434058, 2 434 096, 2 646 348, 2 714 588 and 2 743 298, have been given shape-stabilizing properties.
  • chromium (VI) compounds on the pyrophoric particle, an iron and chromium oxide surface layer is now formed and then this surface layer, be it during its formation or only immediately afterwards modified with at least one of the elements mentioned.
  • a chromium spinel of the general formula (Me (II) O) (Me (III)] 2 O 3 can be assumed for the structure of the surface layer which surrounds the core.
  • This surface layer is now obtained by incorporating divalent or trivalent metal ions or by a combination thereof
  • Me (II) ions mentioned Zn is particularly preferred.
  • Zn is particularly preferred.
  • divalent, oxidation-stable cations is advantageous because in their absence there is a deficiency of Fe (II) in relation to the formation of chromite.
  • Al (III) ions has also proven to be expedient.
  • a composition according to the formula is for the chromite forming the surface layer expected.
  • the divalent and / or trivalent metal ions contained according to the invention in the surface layer are advantageously used in the form of their aqueous solutions.
  • especially soluble salts of inorganic or organic acids such as. B. sulfates, chlorides, acetates are suitable. Salts which, like nitrates, can have an oxidizing effect on iron were not used, since this can result in the formation of oxidic surface layers with different properties.
  • the anions of the selected salts should have no or only a slightly reducing effect under the chosen conditions in order to make the yield in relation to Cr (VI) favorable during the Cr (VI) treatment.
  • phosphate ions P0 4 3-
  • phosphate ions and further metal ions or phosphate ions and combinations of metal ions into the surface layer consisting of iron, chromium and oxygen ions.
  • the possible formation of poorly soluble Me (II) and / or Me (III) phosphates such as Zn 3 (PO 4 ) 2 ; CrP0 4 , FeP0 4 or AIP0 4 also leads to surface layers with favorable properties.
  • the known treatment with chromium (VI) compounds is used to produce the ferromagnetic metal particles according to the invention.
  • the pH quickly shifts to the alkaline range, whereby pH values up to almost 13 can be reached.
  • Equation (1) indicates a possible reaction for the release of these OH ions.
  • the pH can be controlled with the aid of the metal salts suitable for forming the surface layer, be it by hydrolysis of acidic metal salts, such as zinc chloride, or by the precipitation of the OH ions released as corresponding metal hydroxides. In this way, an extensive consumption of the added oxidizing agent and thus a chromium (VI) -free product required for later use is achieved.
  • chromium (VI) compounds dichromates such as K 2 Cr 2 O 7 or Na 2 Cr 2 0 7 , chromates such as Na 2 Cr0 4 or K 2 Cr0 4 and chromium (VI) oxide (Cr0 3 ) are suitable.
  • the aqueous solutions of the above-mentioned Cr (VI) compounds can, if necessary, be adjusted to acidic pH values by adding acids such as H 2 SO 4 , HCl, H 3 PO 4 .
  • the proportion of chromium incorporated into the surface layer can be varied by the test conditions, such as pH, temperature and the amount of Cr (VI) used, larger amounts of Cr (VI) being expected to lead to increased chromium incorporation.
  • Cr (VI) solutions can be used that contain between 10 and 230 g of Cr (VI) per 1 kg of metal pigment used. However, solutions are preferred which contain between 25 and 80 g of Cr (VI) per 1 kg of metal pigment.
  • the metal particles are treated with Cr (VI) compounds with stirring in aqueous suspensions, with dilutions (pigment: solution weight ratios) of 1: 5 to about 1:20 having proven to be expedient. If the dilution is 1:10, the pH value which may have been adjusted by adding acid should not be less than 2.3. For other dilutions, this minimum pH value can easily be determined by experiment.
  • inhibitors according to the prior art can advantageously be used in metal pickling for such treatment solutions or suspensions.
  • the structure of the surface layer according to the invention is not affected by this.
  • Some such inhibitors and their use in pickling treatment are e.g. B. in Z. Metallischen 69, pages 1 to 7 (1978). Thereafter, z. B. diphenylthiourea, propargyl alcohol or 1,4-butynediol.
  • the treatment temperatures should be between 15 and about 75 ° C, in particular between room temperature and 70 ° C.
  • the duration of treatment is approximately 2 to 30 minutes.
  • the surface layers of the metal particles according to the invention are also obtained.
  • the procedure described below has proven to be particularly advantageous.
  • aqueous solutions of the divalent and / or trivalent metal ions are added to the alkaline reacting suspensions.
  • the corresponding metal hydroxides can precipitate and be applied to the pigment surface.
  • Precipitation of the hydroxides advantageously lowers the pH of the suspension. This facilitates the subsequent filtration and washing out of the treated pigments.
  • the pH at which the addition of the metal ions ends depends on the amount of metal ions to be incorporated and on the solubilities of the hydroxides formed. For example, the minimum solubility of Cd (OH) 2 is close to pH 11 and that of Zn (OH) 2 is close to 9.5.
  • solubilities of the metal hydroxides formed are sufficiently small, e.g. B. are less than about 0.5 g of metal ion / I, the addition of metal ions for hydroxide precipitation can continue into the weakly acidic range. If necessary, to precipitate larger amounts of hydroxides after the Cr (VI) treatment has ended, the alkaline pH already present can be increased by adding bases.
  • the resulting product is separated from the liquid by filtration and optionally washed. This can be done with water, with mixtures of water with water-soluble organic solvents or with the aforementioned organic solvents themselves. Reducing agents which are oxidized by Cr (VI) compounds under the chosen working conditions can optionally be added to the washing liquids. As a result, chromium (VI) which is not sufficiently washed in the filter cake is reduced to Cr (III).
  • Suitable reducing agents are, for example, Fe (II) ions, sulfites (SO 3 2- , HS0 3 - ), hydrazine or its salts, hydroxylamine, formaldehyde or easily oxidizable organic compounds such as. B. ascorbic acid.
  • Aqueous washing solutions of reducing agents whose oxidation products are gaseous, readily soluble, easily washable or already present in the surface layer of the metal particle are preferred.
  • the resulting product is then dried and the metal particles according to the invention are annealed to form the surface layer. Drying takes place in a vacuum or at normal pressure. Depending on the drying method selected, temperatures of 80 to 320 ° C and periods of 0.5 to 8 hours have proven to be suitable. During these periods, drying and tempering are usually carried out in one process step. Of course, drying and tempering can also be carried out in two separate process steps. Although small amounts of oxygen in the surrounding gas atmosphere interfere little at low treatment temperatures, the drying process and the annealing process is preferred under inert gases such as. B. nitrogen or noble gases. Drying and tempering at normal pressure is also preferred. Drying at normal pressure and temperatures between about 80 and 320 ° C results in non-flammable materials in air at room temperature.
  • the treatment of the metal particles to be improved for the production of the particles provided with a surface layer according to the invention is also to be carried out in such a way that the pH value during the Cr (VI) treatment by the addition of divalent and / or trivalent metal ions and the resulting hydroxide precipitation is regulated to the desired value.
  • the pH value which is favorable for the particular metal ions added can be derived from the solubilities of the corresponding hydroxides.
  • metal salts such as. B. ZnC1 2 , react acidic due to hydrolysis.
  • the metal particles according to the invention are to have surface layers with Me (II) ions which form poorly soluble chromates Me (11) Cr0 4 like Ca, Sr, Va, Cd, Zn or Pb, then it has proven to be expedient to add the corresponding metal compounds add finished chrome (VI) treatment of the metal particles in the alkaline range. It is advantageous to reslurry the filter cake, which may have been pre-washed with water, after the chromium (VI) treatment and then to add the intended amount of Me (II) ions to the suspension while stirring.
  • phosphorus in the form of phosphate is selected from the group of modifying elements for the formation of the surface layer of the metal particles according to the invention, it has proven to be advantageous in the elaboration of the method according to the invention either in the chromium (VI) treatment of the metal particles the pH Value to regulate already by the addition of phosphoric acid or to add the phosphate ion in the form of primary, secondary or tertiary phosphates to the aqueous solution of the chromium (VI) compound.
  • the metal particles according to the invention produced by this process are particularly advantageously suitable for achieving the object if they have a surface layer, which, in addition to iron, oxygen and 1 to 9% by weight of chromium, based on the total amount of the metal particle, additionally contains at least one of the following elements in the stated amount:
  • these metal particles according to the invention have better magnetic properties. They are therefore outstandingly suitable for use in the production of magnetic recording media, since, owing to their greater stability, they can be more easily incorporated into the binder systems forming the magnetic layer, and important mechanical properties of these magnetic recording media are also improved.
  • the magnetic values of the metal powders were measured with a vibration magnetometer at a magnetic field of 160 kA / m.
  • the values of the coercive force, H c , measured in kA / m, were based on a stuffing density of p 1.6 g / cm 3 in the powder measurements.
  • Specific remanence M R / p and saturation M s / ⁇ are given in nTm 3 / g.
  • a pyrophoric metal pigment for magnetic properties see Table 1
  • 100 g of a pyrophoric metal pigment (for magnetic properties see Table 1) produced by reduction of acicular goethite with a particle length of 0.51 ⁇ m and a length / thickness ratio of 28.3 with hydrogen in a vortex furnace at 350 ° C, are in 1000 ml Water suspended at 30 ° C. These suspensions are then mixed with stirring with 1.2 g (Experiment 1A), 2.5 g (Experiment 1 B) and with 7.5 g (Experiment 1 C) chromium (VI) ions in the form of an aqueous potassium dichromate solution .
  • a pyrophoric metal pigment produced by reduction of acicular goethite with a particle length of 0.51 ⁇ m and a length / thickness ratio of 28.3 with hydrogen in a vortex furnace at 350 ° C., are suspended in 1000 ml of water at 30 ° C. This suspension is then mixed with stirring 7.5 g of chromium (VI) ions in the form of an aqueous potassium dichromate solution. After stirring for 10 minutes, the pH of the suspension is 11.3. Now 19.8 g of ZnS0 4 . 7 H 2 0 dissolved in 75 ml of water to adjust the pH to 7 and to precipitate hydroxide, and the mixture was stirred for a further 3 minutes. The end product is worked up as described in Example 1. The results are shown in Table 2.
  • Example 2 The procedure is as described in Example 2, but instead of the zinc sulfate solution, the salts of calcium, strontium, barium, cadmium and nickel shown in Table 3 are each added to the suspension in the stated amounts dissolved in 100 ml of water.
  • a pyrophoric iron pigment prepared as in Example 1 is treated as described in Example 1. However, the initial charge of K 2 Cr 2 O 7 and water is adjusted to a pH of 2.3 with dilute sulfuric acid. The temperature of the initial charge was 22 ° C. While stirring, 150 g of metal pigment were introduced into the initial charge consisting of 2250 ml of water and the Cr (VI) compound. The pH is then adjusted to 12 by adding NaOH and then a solution of 150 g of Al 2 (SO 4 ) 3 .18 H 2 O and 60 g of ZnSO 4 .7 H 2 0 in 200 ml of water is added.
  • Example 14 The procedure is as described in Example 14, but 3 minutes after the addition of the phosphoric acid K 2 Cr 2 0 7 solution the pH is adjusted to 12.0 with an aqueous solution of NaOH. A solution of 37.5 g of ZnSO 4 - 7 H 2 0 in 125 ml of water is then added dropwise, and a pH of 7.0 is thereby achieved. After 5 minutes, work up as described. The results are shown in Table 6.
  • pyrophoric metal pigment according to Example 14 150 g of pyrophoric metal pigment according to Example 14 are added with stirring to a template of 31.5 g of K 2 Cr 2 O 7 , 5 g of propargyl alcohol, H 2 SO 4 and 2250 ml of water, which has a pH of 2.3 . After 4 minutes, the pH, which has meanwhile risen to 10, is adjusted to 7 by dropwise addition of a solution of 31.5 g of ZnSO 4 - 7 H 2 0, 50 ml of H 2 0 and 50 ml of dilute phosphoric acid, and this pH is maintained for a further 5 minutes with further dropwise addition . Then the approach is worked up. The results are shown in Table 6.
  • the coefficient of friction of the magnetic tape is measured before (v. DI.) And after endurance (n. DI.).
  • a ribbon loop of 95 cm in length is pulled over an arrangement of magnetic heads at a speed of 4 m / sec for 1 hour.
  • the weight loss of the tape is assessed in milligrams (abrasion).
  • the endurance run is a measure of the tendency to smear (head deposits) and the wear resistance (weight loss).

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Paints Or Removers (AREA)
  • Chemical Treatment Of Metals (AREA)
  • Hard Magnetic Materials (AREA)

Claims (5)

1. Particules métalliques ferromagnétiques, constituées essentiellement de fer, avec un noyau comportant au moins 85% en poids de fer métallique et une couche superficielle de fer et d'oxyde de chrome entourant ce noyau, caractérisées par le fait que les particules métalliques dans la couche superficielle, outre du fer, de l'oxygène et 1 à 9% en poids de chrome, rapportée à la totalité de la particule métallique, contiennent encore en plus au moins un élément, non dérivé du noyau, choisi dans le groupe du zinc, phosphore sous forme de phosphate, aluminium, calcium, strontium, baryum, cadmium, plomb, cobalt et nickel, en quantité totale ne dépassant pas 9,5% en poids, rapportée à la totalité de la particule métallique.
2. Particules métalliques ferromagnétiques, constituées essentiellement de fer, selon la revendication 1, caractérisées par le fait que la couche superficielle, outre du fer, de l'oxygène et 1 à 9% en poids de chrome, rapportée à la totalité de la particule métallique, contient encore, en plus, au moins un des éléments suivants, dans les quantités indiquées:
Figure imgb0013
3. Procédé de préparation des particules métalliques ferromagnétiques, constituées essentiellement de fer, selon la revendication 1 ou 2, caractérisé par le fait que, pendant la formation de la couche superficielle contenant du chrome, par traitement des particules métalliques avec une solution de composés de Cr(VI), on ajoute à la solution, et on précipite sur les particules métalliques, au moins les ions métal d'un élément du groupe du zinc, aluminium, calcium, strontium, baryum, cadmium, plomb, cobalt et nickel ou des ions phosphate ou au moins un de ces ions métal et phosphate, et on recuit ensuite ie matériau résultant à des températures comprises entre 80 et 320° C, pendant 0,5 à 8 heures.
4. Procédé de préparation des particules métalliques ferromagnétiques, constituées essentiellement de fer, selon la revendication 1 ou 2, caractérisé par le fait que, après la formation de la couche superficielle contenant du chrome, par traitement des particules métalliques avec une solution de composés de Cr(VI), on précipite sur la surface des particules résultantes au moins les ions métal d'un élément du groupe du zinc, aluminium, calcium, strontium, baryum, cadmium, plomb, cobalt et nickel, ou des ions phosphate ou au moins un de ces ions métal et phosphate, et on recuit ensuite le matériau résultant à des températures comprises entre 80 et 320° C, pendant 0,5 à 8 heures.
5. Utilisation des particules métalliques ferromagnétiques, constituées essentiellement de fer, selon les revendications 1 et 2, pour la préparation de supports d'enregistrement magnétiques.
EP81104590A 1980-07-15 1981-06-15 Particules métalliques ferromagnétiques constituées essentiellement de fer ayant une couche de revêtement superficiel, procédé pour leur préparation ainsi que leur utilisation pour la fabrication des supports d'enregistrement magnétiques Expired EP0043921B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19803026696 DE3026696A1 (de) 1980-07-15 1980-07-15 Ferromagnetische, im wesentlichen aus eisen bestehende metallteilchen mit einem oberflaechenueberzug, verfahren zu deren herstellung sowie ihre verwendung zur herstellung von magnetischen aufzeichnungstraegern
DE3026696 1980-07-15

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EP0043921B1 true EP0043921B1 (fr) 1984-05-16

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Families Citing this family (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS59153810A (ja) * 1983-02-22 1984-09-01 Chisso Corp 強磁性金属微粒子の製造法
US4544463A (en) * 1983-05-27 1985-10-01 Olin Corporation Method for producing equiaxed iron or iron alloy particles
CA1226456A (fr) * 1984-01-12 1987-09-08 Michael J. Pryor Methode et appareil de production de particules aciculaires de fer ou d'alliage de fer
SU1256394A1 (ru) * 1984-04-24 1987-06-07 Институт Органического Синтеза Ан Латвсср Производные 15( @ + @ )-фтор-11,15-дидезоксипростагландина @ ,обладающие антиагрегационной активностью
SE442487B (sv) * 1984-05-24 1986-01-13 Hoeganaes Ab Forfarande for framstellning av en sintrad kompositkropp
GB8425860D0 (en) * 1984-10-12 1984-11-21 Emi Ltd Magnetic powder compacts
DE3438093A1 (de) * 1984-10-18 1986-04-24 Basf Ag, 6700 Ludwigshafen Ferrimagnetische teilchen und verfahren zu ihrer herstellung
US4585617A (en) * 1985-07-03 1986-04-29 The Standard Oil Company Amorphous metal alloy compositions and synthesis of same by solid state incorporation/reduction reactions
GB2181445B (en) * 1985-10-09 1989-11-08 Tdk Corp Magnetic recording medium
EP0260870A3 (fr) * 1986-09-12 1989-04-19 Minnesota Mining And Manufacturing Company Aimant du type métal lié pour polymère comprenant des particules métalliques résistant à la corrosion
GB8629574D0 (en) * 1986-12-10 1987-01-21 Sherritt Gordon Mines Ltd Filtering media
US4780153A (en) * 1987-02-06 1988-10-25 Guhde Donald J Chromium-containing low-cure coating composition
US4743466A (en) * 1987-06-05 1988-05-10 Eastman Kodak Company Corrosion inhibition of iron and its alloys
AU599415B2 (en) * 1987-08-31 1990-07-19 Nippon Paint Co., Ltd. Metal particle
US5240742A (en) * 1991-03-25 1993-08-31 Hoeganaes Corporation Method of producing metal coatings on metal powders
DE4294047T1 (de) * 1991-11-22 1996-09-26 Ampex Media Corp Lagerung von Metallteilchen
DE69313273T2 (de) * 1992-04-14 1997-12-04 Byelocorp Scient Inc Magnetorheologische flüssigkeiten und herstellungsverfahrens
US5828142A (en) * 1994-10-03 1998-10-27 Mrs Technology, Inc. Platen for use with lithographic stages and method of making same
DE19735271C2 (de) * 1997-08-14 2000-05-04 Bosch Gmbh Robert Weichmagnetischer, formbarer Verbundwerkstoff und Verfahren zu dessen Herstellung
SE0100236D0 (sv) * 2001-01-26 2001-01-26 Hoeganaes Ab Compressed soft magnetic materials
DE20122873U1 (de) 2001-03-03 2008-10-30 Robert Bosch Gmbh Metallpulver-Verbundwerkstoff und Ausgangsmaterial
JP2022026524A (ja) * 2020-07-31 2022-02-10 太陽誘電株式会社 金属磁性粉末及びその製造方法、並びにコイル部品及び回路基板

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1052585A (fr) 1964-06-13
US3865627A (en) * 1972-05-22 1975-02-11 Minnesota Mining & Mfg Magnetic recording medium incorporating fine acicular iron-based particles
US3837912A (en) * 1972-05-22 1974-09-24 Minnesota Mining & Mfg Environmentally stable iron-based magnetic recording medium
US3932293A (en) * 1972-05-22 1976-01-13 Minnesota Mining And Manufacturing Company Metallic ferromagnetic particles for use in environmentally stable magnetic recording media
DE2434096C2 (de) 1974-07-16 1985-10-17 Basf Ag, 6700 Ludwigshafen Nadelförmige, vorwiegend aus Eisen bestehende ferromagnetische Metallteilchen und Verfahren zu ihrer Herstellung
DE2434058C2 (de) 1974-07-16 1985-12-19 Basf Ag, 6700 Ludwigshafen Nadelförmige, vorwiegend aus Eisen bestehende ferromagnetische Metallteilchen und Verfahren zu ihrer Herstellung
US4092459A (en) * 1975-01-13 1978-05-30 Graham Magnetics Incorporated Powder products
JPS6044805B2 (ja) * 1976-08-27 1985-10-05 日本ビクター株式会社 磁気記録媒体の製造方法
DE2646348C2 (de) * 1976-10-14 1986-08-28 Basf Ag, 6700 Ludwigshafen Verfahren zur Herstellung von nadelförmigen, ferromagnetischen, im wesentlichen aus Eisen bestehenden Metallteilchen und deren Verwendung zur Herstellung von magnetischen Aufzeichnungsträgern
DE2714588C2 (de) 1977-04-01 1986-06-05 Basf Ag, 6700 Ludwigshafen Verfahren zur Herstellung nadelförmiger ferromagnetischer Eisenteilchen
DE2743298A1 (de) * 1977-09-27 1979-04-05 Basf Ag Ferromagnetische, im wesentlichen aus eisen bestehende metallteilchen und verfahren zu deren herstellung

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DE3026696A1 (de) 1982-02-18
EP0043921A1 (fr) 1982-01-20
US4360377A (en) 1982-11-23
DE3163612D1 (en) 1984-06-20

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