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
  • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
  • B22F1/05—Metallic powder characterised by the size or surface area of the particles
  • B22F1/054—Nanosized particles
• • 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
  • B22F9/02—Making metallic powder or suspensions thereof using physical processes
  • B22F9/026—Spray drying of solutions or suspensions
• • 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
  • B22F9/20—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from solid metal compounds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G39/00—Compounds of molybdenum
  • C01G39/006—Compounds containing molybdenum, with or without oxygen or hydrogen, and containing two or more other elements
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G41/00—Compounds of tungsten
  • C01G41/006—Compounds containing tungsten, with or without oxygen or hydrogen, and containing two or more other elements
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G49/00—Compounds of iron
  • C01G49/0018—Mixed oxides or hydroxides
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G51/00—Compounds of cobalt
  • C01G51/80—Compounds containing cobalt, with or without oxygen or hydrogen, and containing one or more other elements
  • C01G51/82—Compounds containing cobalt, with or without oxygen or hydrogen, and containing two or more other elements
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G53/00—Compounds of nickel
  • C01G53/80—Compounds containing nickel, with or without oxygen or hydrogen, and containing one or more other elements
  • C01G53/82—Compounds containing nickel, with or without oxygen or hydrogen, and containing two or more other elements
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C27/00—Alloys based on rhenium or a refractory metal not mentioned in groups C22C14/00 or C22C16/00
  • C22C27/06—Alloys based on chromium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C30/00—Alloys containing less than 50% by weight of each constituent
  • C22C30/02—Alloys containing less than 50% by weight of each constituent containing copper
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C9/00—Alloys based on copper
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/60—Particles characterised by their size
  • C01P2004/62—Submicrometer sized, i.e. from 0.1-1 micrometer
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/12—Surface area
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/80—Compositional purity

Definitions

• the invention relates to novel metallic micron powders based on tungsten and / or molybdenum and 3d transition metals.
• the metal parts used concretely are generally metal alloys. It is recalled that the metal alloys, according to the characteristics of mutual solubility of the constituent metals, can be single-phase or polyphase systems. The production of sintered parts using a mixture of pure metal powders raises difficulties when it is desired to obtain a homogeneous sintered part.
• suspensions containing the metal salts or hydroxides can be prepared in the required proportions, and the suspensions obtained are subjected to a co-drying operation by atomization. Particles are thus obtained whose composition in metal salts and / or hydroxides is homogeneous. These particles can then be reduced to pre-alloyed metal powders using a reducing agent. It is known that the techniques for preparing metal powders generally lead to the production of agglomerates constituted by several elementary grains linked together punctually. Grinding techniques generally make it possible to increase the number of individual elementary grains, and to reduce the number of elementary grains present in the aggregates. As indicated above, the invention relates to micron powders.
• micron powders are called powders such that the largest dimension of the elementary grains is greater than 200 nm and less than or equal to 5 micrometers.
• the dimensions of the elementary grains can be measured in particular with a scanning electron microscope.
• Micron powders must be distinguished from nanometric powders, the elementary grains of which have dimensions of less than approximately 100 nm.
• the invention relates to new metal powders based on tungsten and / or molybdenum and based on at least one 3d transition metal chosen from iron, cobalt, nickel and copper.
• the powders of the invention have advantageous properties in various applications, as will be specified in the following description.
• the subject of the invention is therefore a pre-alloyed metal powder consisting essentially of tungsten and / or molybdenum, of at least one transition metal chosen from iron, cobalt, nickel and copper, and optionally at least one additive, the iron content being less than 50% by weight and the total additive content being less than 3% by weight, relative to the total weight of metals, said pre-alloyed metal powder having elementary grain dimensions, measured with an electron microscope scanning, greater than 200 nm and less than 5 micrometers, with the exception of a powder consisting essentially of tungsten, iron and nickel; as well as a sintered part obtained using such a powder.
• a powder “consisting essentially” of such and such a metal contains each of these metals in an amount of more than 1% by weight, and in particular of more than 3% by weight. weight.
• essential constituents contains each of these metals in an amount of more than 1% by weight, and in particular of more than 3% by weight. weight.
• Such a constituent when it can be used at a rate of less than 3%, and in particular less than 2% or less than 1%, is then considered as an additive in the alloys where it is present in such small proportions.
• the additives can in practice be any metal or metalloid capable of improving the properties of the powders or sintered parts.
• the additives can be chosen in particular from all the metals which are not essential constituents (as defined above) of the powder, or the oxides of these metals.
• the purpose of the presence of additives may in particular be to improve the sintering operations. It is known that the presence of an additive, even in very small quantities (for example of the order of 0.1%) often often significantly lowers the sintering temperature. The choice of additives and their quantity can be determined by simple routine experiments.
• metal percentages are percentages by weight based on the total weight of metal powder. It is known that metal powders tend to oxidize in air, this oxidation increasing over time and with the more or less oxidizable nature of the metals present.
• the total oxygen content (measured by reduction using carbon), leaving the oven where the reduction of hydroxides and / or metal salts has been carried out, is generally less than 2% based on the total weight of the powder.
• the powders of the invention can be prepared according to the coprecipitation and optionally spray drying methods, followed by reduction, which have been described above and which are known per se.
• the choice of temperature and reduction time can be determined using simple routine experiments, including thermogravimetric analysis. We can optimize the size of the elementary grains knowing that this size increases with temperature and with the duration of heating, during the reduction operation.
• the invention also relates to sintered parts obtained from such powders, and more generally to all finished industrial articles containing these powders.
• the additives can be chosen in particular from iron and cobalt; each additive, if present, can represent for example less than 1% of the total weight of the metals of the powder.
• the powders based on tungsten and / or molybdenum and copper can be used in particular in the production by sintering of electrical contact parts or of EDM electrodes. In particular, they have good properties of resistance to the harmful effects of the electric arc (corrosion, oxidation).
• Such powders can also be used for the production of sintered parts intended to be used as heat sinks (or radiators) whose function is to evacuate the heat in certain devices.
• Such powders can be used in particular for preparing by sintering balancing masses, inertial units, tool holders, radiation shields, or even armaments.
• Such powders can be used in particular in the manufacture by sintering of diamond tools, in place of the cobalt-based binders conventionally used.
• powders consisting essentially of 15 to 40% of copper, of 50 to 80% of nickel and of 5 to 20% of molybdenum. These powders can be mixed, as an additive, with iron powder, and optionally with carbon (for example graphite) to obtain sintered steels.
• Such powders can serve as binders in the preparation by sintering of diamond tools.
• Such a binder improves the mechanical properties of diamond tools.
• powders consisting essentially of molybdenum, cobalt and nickel, and optionally at least one additive.
• Such powders can be used in particular as binders in the preparation by sintering of cermets, that is to say cutting or abrasion tools containing titanium carbide.
• the invention also relates to the use of a powder as defined above in the production of sintered parts which can be used as electrical contacts, heat sinks, EDM electrodes, mechanical balancing masses, inertial units, tool holders, radiation shields, armaments, sintered steels or diamond or titanium carbide cutting or abrasion tools.
• a powder as defined above in the production of sintered parts which can be used as electrical contacts, heat sinks, EDM electrodes, mechanical balancing masses, inertial units, tool holders, radiation shields, armaments, sintered steels or diamond or titanium carbide cutting or abrasion tools.
• the fields of application of the various categories of powders have been specified above.
• the powders of the invention used in obtaining sintered parts, have the advantage of improving the mechanical or physical properties of the parts obtained and / or the advantage of facilitating sintering by allowing in particular to operate at temperatures and / or pressures not too high and / or to improve the densification of the sintered parts.
• the following examples illustrate the invention.
• the raw materials used are cobalt chloride C0CI2, used in the form of an aqueous solution containing 170.6 g / L of cobalt; crystallized ferric chloride FeCl, 6H2O, purity
• solutions containing approximately 200 g / liter of the various metals are prepared.
• the metal salt solution is heated to 60 ° C and poured into an aqueous sodium hydroxide solution, itself heated to 60 ° C, with stirring.
• the amount of sodium hydroxide is calculated so as to use a 10% excess of sodium hydroxide relative to the stoichiometry of formation of hydroxides from salts.
• Stirring is continued for 1 hour, at a temperature of 60 ° C. We filter.
• the precipitate is washed 3 times by resuspending it in 3.5 L of water heated to 60 ° C and then filtering.
• hydroxide precipitate is then resuspended in water and hydrated ammonium metatungstate called hereafter AMT, containing 85.98% of oxide W03, is added with stirring, in the form of an aqueous solution, shaking strongly.
• AMT ammonium metatungstate
• composition No. 1 293 cnJ of the cobalt chloride solution; 404.1 g of ferric chloride; 233.7 g of nickel chloride and 20.53 g of ammonium metatungstate (AMT); - Composition No. 2: 293 crrJ of the cobalt chloride solution; 101 g of ferric chloride; 208.7 g of nickel chloride and 117.34 g of AMT;
• the powders obtained were then reduced in an oven under a hydrogen atmosphere.
• the oven is divided into three zones, the temperatures of which are set independently.
• the powder samples are automatically moved into the oven so that the total passage time is 9 and a half minutes.
• the temperature zones were adjusted to 600-700-750 ° C for compositions n ° 1 to n ° 3 and 500-600-650 ° C for composition n ° 4.
• the powders obtained after reduction have the following composition (% by weight): Powder No. 1: W 9.6; Co 23.4; Fe 37.9; Ni 27.4; oxygen 1.7
• Powder # 2 W 39; Co 23.8; Fe 10.9; Ni 26.6; oxygen 0.5
• Powder No. 3 W 53.8; Co 23.7; Cu 20.5; oxygen 2
• the oxygen content measured is total oxygen.
• the powders are then subjected to the action of a nitrogen jet mill so as to reduce the size of the agglomerates.
• Sintering is carried out using a high temperature high pressure apparatus.
• the matrix used is a graphite matrix with 4 cylindrical punches.
• the sintered parts are pins 20 mm in diameter and 5 mm thick.
• the quantity of powder required to obtain a sintered part having these dimensions is calculated as a function of the theoretical density.
• the sintering temperatures were 800 ° C for powder # 1, 1000 ° C for powder # 2, 950 ° C for powder # 3 and 800 ° C for powder # 4.
• An aqueous solution containing the copper and nickel chlorides is prepared by mixing 6.61 liters of a cupric chloride solution (211 g / l copper) with 17.65 liters of a nickel chloride solution ( 175.9 g / 1 nickel). This solution is poured with stirring into 50 liters of a sodium hydroxide solution titrating 132 g / 1 heated to 60 ° C., so as to effect the coprecipitation of the hydroxides of copper and nickel. The precipitate thus obtained is then separated by filtration and then washed. The precipitate is resuspended in water at the rate of approximately 5 liters of water per 1 kg of precipitate.
• molybdic acid consists essentially of ammonium molybdate.
• An aqueous solution containing the chlorides of cobalt and nickel by mixing 14 liters of a solution of cobalt chloride with 172 g / l of cobalt with 13.7 liters of a solution of nickel chloride with 175.9 g / l of nickel.
• This solution is poured with stirring into 40 liters of a sodium hydroxide solution titrating 187.5 g / 1 heated to 60 ° C, so as to effect the coprecipitation of the cobalt and nickel hydroxides.
• the precipitate thus obtained is then separated by filtration, then washed.
• the precipitate is resuspended in water at the rate of approximately 5 liters of water per 1 kg of precipitate.
• This powder is then cold compacted into parallelepipedic test pieces of approximately 60% relative density.
• a sintering operation in a hydrogen furnace (rise in 5 hours at 1100 ° C, then leveling for 1 hour at 1100 ° C, then cooling in approximately 12 hours) these test pieces acquire a density equal to 97.3% of the density theoretical.
• the structure of a polished cross section of the sintered part appears to be very fine and very homogeneous.
• powders were prepared containing (% by weight):
• Average size of the elementary grains 0.5 ⁇ m

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• 1998
  • 1998-10-16 FR FR9813032A patent/FR2784690B1/fr not_active Expired - Fee Related
• 1999
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