Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
  • C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
  • C23C8/24—Nitriding
• • 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
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B21/00—Nitrogen; Compounds thereof
  • C01B21/06—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron
  • C01B21/072—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron with aluminium
  • C01B21/0722—Preparation by direct nitridation of aluminium
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L23/00—Details of semiconductor or other solid state devices
  • H01L23/12—Mountings, e.g. non-detachable insulating substrates
  • H01L23/14—Mountings, e.g. non-detachable insulating substrates characterised by the material or its electrical properties
  • H01L23/15—Ceramic or glass substrates
• • 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
  • B22F2201/00—Treatment under specific atmosphere
  • B22F2201/02—Nitrogen
• • 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
  • C01P2006/10—Solid density
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
  • H01L2924/0001—Technical content checked by a classifier
  • H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Definitions

• the present invention relates to a new process for the preparation of partially or totally nitrided aluminum granules, the granules thus obtained and their use.
• Aluminum nitride is a well known material, very advantageous in particular for its use in the manufacture of substrates for integrated circuits, in electronics or also for the manufacture of various expanded materials, in particular glass foam.
• the rate of nitriding of aluminum depends on various parameters such as the reaction time (contact time between the aluminum powder to nitride and the nitriding agent) or its temperature, the skilled person knowing perfectly define said parameters to obtain complete nitriding of the aluminum, or simply partial.
• the present invention therefore relates to a new process for the preparation of aluminum nitride granules, wholly or in part, stable in storage, which can be maintained under normal atmosphere without being hydrolysed and give off ammonia, the granules obtained by the process being coated with a passivating layer of calcium carbonate (CaCO 3 ).
• the method according to the invention thus makes it possible to obtain granules of a mixture of aluminum and aluminum nitride comprising up to 40% by weight of aluminum nitride which makes it possible to manufacture cermets which are not cannot be obtained by another process.
• the process according to the invention consists in reacting, with continuous stirring, the aluminum powder in admixture with an appropriate quantity of pulverulent CaCO 3 , with nitrogen by heating the reaction medium to an appropriate temperature.
• CaCO 3 is meant the quantity necessary for obtaining an at least continuous mono-molecular layer of passivating compound around the aluminum nitride granules obtained by the process according to the invention.
• the pulverulent mixture comprises between 1 and 5% by weight of CaCO 2, more advantageously approximately 1.5% by weight of CaCC 2.
• the appropriate temperature is that of the usual techniques for preparing AIN by reaction of aluminum and of particular nitrogen described in FR-A-2 681 590. It is between 600 ⁇ C and 1200 ⁇ C, advantageously less than 1000 ° C, even more advantageously close to 900 ° C.
• the aluminum powder used in the process according to the invention has an average particle size of between 0.1 and 100 ⁇ m, preferably between 0.5 and 60 ⁇ m.
• an aluminum powder for obtaining partially nitride aluminum, more particularly for obtaining "cermets”, an aluminum powder will advantageously be used, the average diameter of which is between 50 and 60 ⁇ m.
• the continuous stirring of the reaction mixture is carried out by means of a rotary oven.
• the continuous stirring is carried out by means of a swept bed reactor or of a fluidized bed reactor.
• the pulverulent mixture of aluminum and calcium carbonate is introduced into the furnace, under a nitrogen atmosphere which is introduced against the flow of the pulverulent mixture.
• nitrogen is introduced at an hourly space velocity, quotient of the gas flow passing through the reactor through the passage section of said reactor, between 6,000 and 15,000 m. h- ”.
• the granules obtained by the above process have particularly advantageous properties, both for granules essentially consisting of TAIN (fully nitride aluminum) and for partially nitride aluminum, in particular the granules for "cermets" comprising up to at 40% by weight of aluminum nitride.
• the present invention therefore also relates to new granules of aluminum nitride, wholly or in part, constituted by a core of aluminum nitride, wholly or in part, and coated with a passivating layer of an appropriate passivating compound, in particular carbonate. calcium.
• the granules according to the invention preferably have an average diameter of between 5 and 40 mm. By mean diameter is meant the size of the mesh of a sieve in which the granules according to the invention would flow by gravity.
• the passivating layer of the passivating compound is at least mono ⁇ molecular, continuous, that is to say, for calcium carbonate, an average thickness of at least 10 Angstroms.
• the passivating layer can have a thickness greater than that of a mono-molecular layer.
• the passivating layer will be essentially mono-molecular, that is to say having the minimum quantity of suitable passivating compound making it possible to create a continuous layer around the nitrided aluminum core ensuring its passivation without denature the physico-chemical properties of this product.
• the weight ratio of nitrided aluminum core / CaCOj will advantageously be between 20: 1 and 100: 1, advantageously greater than or equal to 50: 1.
• the granules according to the invention contain up to 40% by weight of aluminum nitride, calculated on the total weight of the core.
• they comprise between 5 and 30% by weight of aluminum nitride.
• the aluminum used is a commercial aluminum which is in a lamellar form, with an apparent density of 0.5 and a specific surface, measured with BET, of 4.95 m 2 / g.
• Calcium carbonate is also a commercial carbonate with an apparent density of 2.7.
• the rotary kiln includes a perfectly sealed rotary reactor, various heating zones, a feed hopper, a recovery tank and a gas supply circuit.
• the reactor rotates at a speed of 3 revolutions per minute, with a working temperature of 880 ⁇ C. Its angle of inclination is approximately 2 °. The passage time of the powder in the reactor depends on this inclination.
• the supply of powder to the reactor takes place in the opposite direction to the arrival of nitrogen.
• the nitrogen flow will be chosen to reach an hourly space velocity of the order of 9,000 m.h-1.
• the powder feed is adjusted to a dispensing speed of 20 g / min.
• the aluminum nitride is recovered in the form of gray-white aggregates of average sizes on the order of a centimeter.
• Example 1 The granules according to the invention obtained in Example 1 below (AIN-gray) were compared with commercial "Stark” AlN (hereinafter A1N-S), with AlN prepared by reacting I ⁇ I 2 O 3 and ammonia (hereinafter AlN-white), and to AlN obtained according to the process described in patent application FR-A-2681 590 (hereinafter AlN-FR).
• A1N-S commercial "Stark” AlN
• AlN-white AlN prepared by reacting I ⁇ I 2 O 3 and ammonia
• AlN-FR AlN obtained according to the process described in patent application FR-A-2681 590
• composition of the various products was eludicc by IR spectroscopy in diffuse reflectance with transform of FOURIER (DRIFTS).
• Another way to check the stability of the granules according to the invention is simply to note the presence or absence of the characteristic odor of ammonia.
• the aluminum used is a commercial aluminum which is in the form of powder of spherical grains with an apparent density of 0.8 and a specific surface area measured at BET of 0.27 m2 / g.
• the average diameter of the spheres is 50 to 60 ⁇ m.
• Carbonate is also a commercial carbonate with an apparent density of 2.7.
• the powder supply to the reactor takes place in the opposite direction to the arrival of nitrogen.
• the nitrogen flow will be chosen to reach an hourly space velocity of around 12,000 mh-1.
• the passage time of the powder in the reactor determines the percentage of nitrogen desired.
• the passage time is determined by the speed of rotation of the reactor as well as the inclination of the latter.
• the working temperature is 850 ⁇ C.
• the granules obtained have an aluminum nitride composition of between 0 and 40% by mass. They can advantageously be used for the manufacture of "cermets" which are ceramic-metal composites. Due to the respective densities of the two constituents of A
• the cermets thus prepared can find applications in aeronautics, aerospace, microelectronics such as, for example, the manufacture of large, low-mass packages and in any other field requiring good mechanical properties associated with low density.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Ceramic Engineering (AREA)
• Inorganic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• General Physics & Mathematics (AREA)
• Computer Hardware Design (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Power Engineering (AREA)
• Ceramic Products (AREA)

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Citations (3)

• 1994
  • 1994-11-18 FR FR9413843A patent/FR2727108A1/fr active Granted
• 1995
  • 1995-11-17 DE DE69509803T patent/DE69509803T2/de not_active Expired - Fee Related
  • 1995-11-17 WO PCT/FR1995/001515 patent/WO1996015982A1/fr not_active Ceased
  • 1995-11-17 EP EP95940327A patent/EP0828688B1/fr not_active Expired - Lifetime

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