EP0275746B1 - Method to produce a composite material, particularly a neutron absorbing composite material - Google Patents
Method to produce a composite material, particularly a neutron absorbing composite material Download PDFInfo
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- EP0275746B1 EP0275746B1 EP87402840A EP87402840A EP0275746B1 EP 0275746 B1 EP0275746 B1 EP 0275746B1 EP 87402840 A EP87402840 A EP 87402840A EP 87402840 A EP87402840 A EP 87402840A EP 0275746 B1 EP0275746 B1 EP 0275746B1
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- 239000002131 composite material Substances 0.000 title claims description 28
- 238000000034 method Methods 0.000 title claims description 24
- 239000002245 particle Substances 0.000 claims description 43
- 239000011159 matrix material Substances 0.000 claims description 24
- 239000000463 material Substances 0.000 claims description 15
- 239000000843 powder Substances 0.000 claims description 15
- 230000008569 process Effects 0.000 claims description 13
- 150000001875 compounds Chemical class 0.000 claims description 11
- 239000011521 glass Substances 0.000 claims description 10
- 229910052751 metal Inorganic materials 0.000 claims description 10
- 239000002184 metal Substances 0.000 claims description 10
- 238000005245 sintering Methods 0.000 claims description 10
- 230000006835 compression Effects 0.000 claims description 7
- 238000007906 compression Methods 0.000 claims description 7
- 239000011230 binding agent Substances 0.000 claims description 6
- 239000006185 dispersion Substances 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 6
- 239000012798 spherical particle Substances 0.000 claims description 6
- 229910001069 Ti alloy Inorganic materials 0.000 claims description 3
- 229910045601 alloy Inorganic materials 0.000 claims description 3
- 239000000956 alloy Substances 0.000 claims description 3
- 239000000919 ceramic Substances 0.000 claims description 3
- 238000002156 mixing Methods 0.000 claims description 3
- 230000001143 conditioned effect Effects 0.000 claims description 2
- 238000010438 heat treatment Methods 0.000 claims 1
- 229940099259 vaseline Drugs 0.000 claims 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 10
- 239000010936 titanium Substances 0.000 description 10
- 229910052719 titanium Inorganic materials 0.000 description 10
- 239000011358 absorbing material Substances 0.000 description 8
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 4
- 238000005260 corrosion Methods 0.000 description 4
- 230000007797 corrosion Effects 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 238000010521 absorption reaction Methods 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 235000019271 petrolatum Nutrition 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 229910000990 Ni alloy Inorganic materials 0.000 description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 2
- 241001639412 Verres Species 0.000 description 2
- 230000004888 barrier function Effects 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000002923 metal particle Substances 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 229910017604 nitric acid Inorganic materials 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 229910010293 ceramic material Inorganic materials 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000000280 densification Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 238000005551 mechanical alloying Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000013528 metallic particle Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000004663 powder metallurgy Methods 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 238000012958 reprocessing Methods 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
Images
Classifications
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C32/00—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ
- C22C32/0047—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with carbides, nitrides, borides or silicides as the main non-metallic constituents
- C22C32/0052—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with carbides, nitrides, borides or silicides as the main non-metallic constituents only carbides
- C22C32/0057—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with carbides, nitrides, borides or silicides as the main non-metallic constituents only carbides based on B4C
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/04—Making non-ferrous alloys by powder metallurgy
- C22C1/05—Mixtures of metal powder with non-metallic powder
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
- G21F1/00—Shielding characterised by the composition of the materials
- G21F1/02—Selection of uniform shielding materials
- G21F1/08—Metals; Alloys; Cermets, i.e. sintered mixtures of ceramics and metals
Definitions
- Neutrophage materials which are commonly used in the nuclear industry, have the function of absorbing the neutrons produced during atomic reactions and ensuring the protection of personnel and the environment against these radiations.
- Boron is generally used to make these neutron-absorbing materials. It is desirable that the quantity of this metal used is not excessively large given its high price.
- a neutron absorbing material should be very light so as not to weigh down the structures, particularly if they are transportable, such as a protective castle which must circulate by road or by rail.
- a neutron-absorbing material should have good resistance to corrosion since for certain applications, such as chemical dissolvers used for the reprocessing of irradiated fuels, the neutron-absorbing materials are in contact with boiling nitric acid.
- the invention relates precisely to a neutron-absorbing composite material consisting of a matrix, for example a metallic one, inside of which a dispersoid element having good neutron absorption properties has been dispersed.
- the article "The mechanism of mechanical alloying" (JS Benjamin and TE Volin) published in the journal Metallurgical Transactions, vol. 5, August 1974, pp. 1929-1934 describes an inlay process which makes it possible to produce a composite material by the dispersion of an insoluble phase consisting for example of refractory oxides and the addition of elements such as aluminum and titanium.
- the dispersion of the elements occurs by cold welding and repeated fractures of the loose powder particles.
- the particle size of the powder is chosen in a range of very small particle size (diameter less than 50 microns). This technique thus makes it possible to incorporate micron hardening particles within the powder grains before sintering. This technique allows in particular to stabilize the homogeneity of the mixture before any handling of the batches of powder.
- FR-A-2 359 665 - C.E.A.- a process for manufacturing parts made of nickel or a nickel alloy by powder metallurgy.
- a layer of Ni3P is deposited on a nickel or nickel alloy powder, the powder thus coated is sintered under load at a temperature between 1000 and 1200 ° C. under a pressure greater than 300 bars for a period at most equal to one hour so as to obtain a so-called "collar" structure corresponding to a heterogeneous structure of the material having large grains surrounded and welded together by finely crystallized grains of smaller dimensions.
- this method is not intended for producing a neutron absorbing material. It does not use B4C particles, which have particularly advantageous properties from the point of view of neutron absorption, one of the technical problems to be solved, according to the invention, being to hold the B4C particles on the material constituting the matrix. In addition, this method does not make it possible to produce a material resistant to a corrosive atmosphere.
- the present invention specifically relates to a process for producing by sintering a composite material, which makes it possible to obtain in a simple, rapid and inexpensive manner a dispersed phase network having mechanical and chemical characteristics which make it particularly suitable for being used as a neutron absorbing material, especially in the nuclear industry. In addition, this material must have good corrosion resistance.
- the invention relates to a composite material obtained by this process and in accordance with claim 6.
- the composite material produced according to the method of the invention is prepared from metal particles 2 of a relatively large diameter, namely greater than 300 microns. These particles are made of a metal, or an alloy of a metal and are intended to constitute the matrix of the composite. They are coated with a deposit consisting of particles of the phase to be dispersed, this phase having to be insoluble in the matrix under the conditions of pressure and temperature of use of the material. These particles, also called dispersoid elements, are a simple element or a compound. They are prepared in the form of spherical particles 4 of much smaller diameter than the particles of the matrix. This diameter is of the order of a micron. For the production of a neutron-absorbing composite material, B4C is preferably used because of its good neutron absorption properties.
- the deposit can be obtained by any method known to those skilled in the art, in particular by the dry or wet method.
- the coated particles are then introduced into a mold 6 (see FIG. 2) having an internal cavity reproducing the shape of the part or parts to be obtained.
- the compact stack of coated particles is then sintered and densified under hot isostatic compression under very high pressure, for example 1000 bars.
- the parts thus obtained are then removed from the mold, and separated from one another.
- the hot isostatic compression is advantageously carried out using a ceramic mold 6 whose internal wall 11 is made of glass low thickness.
- plastic glass perfectly follows the shape being densified. After cooling, the glass layer detaches from the mold and remains at least partially secured to the piece of composite material; this layer thus constitutes an effective barrier against subsequent corrosion or chemical attack due to an aggressive external environment.
- the large diameter particles which are used are easy to coat since they have a reduced specific surface.
- the surface of these particles relative to their volume is smaller than for particles of smaller diameter such as those which are used in the processes of the prior art.
- coated particles assembled in a mold having the shape of the part to be produced, form a compact stack leaving green (raw) with a high porosity, of the order of 30 to 50% of the theoretical density.
- the spherical particles deform and take the form of polyhedra 2a, as shown in the figure 3.
- This hot flow of metal during the working leads to the elimination of the porosity mentioned above. It locally breaks the coating of B4C particles.
- the titanium particles are thus exposed and come into contact with each other directly at certain points 12 of their periphery, without the interposition of dispersoid compound between them.
- wroughtness occurs, that is to say a welding of the titanium particles together by formation of diffusion bridges. This working is necessary for the good integrity of the composite after sintering because it allows a rigid bond of the titanium grains or particles between them, which leads to a material having good mechanical resistance.
- the composite has a structure which, in spite of a regular distribution of the particles of dispersoid compound between the particles of titanium, could be qualified as heterogeneous, insofar as, in certain places, the metallic particles of the matrix are directly related to each other.
- the dispersed phase islands are distributed in the polyhedron joints resulting from the deformation of spherical metal particles.
- a neutron-absorbing composite material was made up of a titanium alloy matrix and a dispersion of B4C.
- the powders thus coated are introduced into a metal casing 6 or a ceramic material having one or more internal cavities 10 reproducing the part or parts to be sintered and the internal wall 11 of which is made of glass.
- composite spheres were molded in a ceramic mold forming a chain of spheres 10 14 mm in diameter.
- the molds 6 are degassed at a temperature between 100 and 300 ° C under vacuum before being sealed.
- the hot isostatic compression is carried out at 1000 ° C. under a pressure of 1000 bars of argon for three hours.
- Composite material spheres are obtained having good mechanical resistance to crushing.
- the glass film remaining on the surface of the spheres of said composite material is an effective barrier against corrosion or against subsequent chemical attack (for example: scrambling nitric acid).
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Metallurgy (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Organic Chemistry (AREA)
- Ceramic Engineering (AREA)
- Physics & Mathematics (AREA)
- General Engineering & Computer Science (AREA)
- High Energy & Nuclear Physics (AREA)
- Powder Metallurgy (AREA)
Description
Les matériaux neutrophages, qui sont couramment utilisés dans l'industrie nucléaire, ont pour fonction d'absorber les neutrons produits au cours de réactions atomiques et d'assurer une protection du personnel et de l'environnement contre ces rayonnements.Neutrophage materials, which are commonly used in the nuclear industry, have the function of absorbing the neutrons produced during atomic reactions and ensuring the protection of personnel and the environment against these radiations.
On utilise généralement le bore pour réaliser ces matériaux neutrophages. Il est souhaitable que la quantité de ce métal utilisée ne soit pas excessivement importante étant donné son prix élevé.Boron is generally used to make these neutron-absorbing materials. It is desirable that the quantity of this metal used is not excessively large given its high price.
En outre, un matériau neutrophage devrait présenter une grande légèreté afin de ne pas alourdir les structures, particulièrement si celles-ci sont transportables, comme un château de protection qui doit circuler par la route ou par voie ferrée.In addition, a neutron absorbing material should be very light so as not to weigh down the structures, particularly if they are transportable, such as a protective castle which must circulate by road or by rail.
Enfin, un matériau neutrophage devrait présenter une bonne résistance à la corrosion étant donné que pour certaines applications, comme les dissolveurs chimiques utilisés pour le retraitement de combustibles irradiés, les matériaux neutrophages sont en contact avec de l'acide nitrique bouillant.Finally, a neutron-absorbing material should have good resistance to corrosion since for certain applications, such as chemical dissolvers used for the reprocessing of irradiated fuels, the neutron-absorbing materials are in contact with boiling nitric acid.
L'invention concerne précisément un matériau composite neutrophage constitué d'une matrice, par exemple métallique, à l'intérieur de laquelle on a dispersé un élément dispersoïde présentant de bonnes propriétés d'absorption des neutrons.The invention relates precisely to a neutron-absorbing composite material consisting of a matrix, for example a metallic one, inside of which a dispersoid element having good neutron absorption properties has been dispersed.
On connaît déjà des procédés permettant de réaliser un matériau composite par frittage.Methods are already known for producing a composite material by sintering.
A titre d'exemple, l'article "The mechanism of mechanical alloying" (J.S. Benjamin et T.E. Volin) paru dans la revue Metallurgical Transactions, vol. 5, août 1974, pp. 1929-1934 décrit un procédé d'incrustation qui permet de produire un matériau composite par la dispersion d'une phase insoluble constituée par exemple d'oxydes réfractaires et l'addition d'éléments tels que l'aluminium et le titane. La dispersion des éléments se produit par des soudures à froid et des fractures répétées des particules de poudre libre. Afin d'obtenir une faible distance entre les particules, la granulométrie de la poudre est choisie dans un intervalle de très faible granulométrie (diamètre inférieur à 50 microns). Cette technique permet ainsi d'incorporer des particules durcissantes microniques au sein des grains de poudre avant frittage. Cette technique permet en particulier de stabiliser l'homogénéité du mélange avant toute manipulation des lots de poudre.For example, the article "The mechanism of mechanical alloying" (JS Benjamin and TE Volin) published in the journal Metallurgical Transactions, vol. 5, August 1974, pp. 1929-1934 describes an inlay process which makes it possible to produce a composite material by the dispersion of an insoluble phase consisting for example of refractory oxides and the addition of elements such as aluminum and titanium. The dispersion of the elements occurs by cold welding and repeated fractures of the loose powder particles. In order to obtain a small distance between the particles, the particle size of the powder is chosen in a range of very small particle size (diameter less than 50 microns). This technique thus makes it possible to incorporate micron hardening particles within the powder grains before sintering. This technique allows in particular to stabilize the homogeneity of the mixture before any handling of the batches of powder.
Toutefois, dans le cas de l'élaboration d'un matériau neutrophage composite par frittage, les propriétés de résistance au fluage et les caractéristiques de fatigue ne sont pas essentielles. La réalisation d'un réseau de phase dispersée avec une maille de diamètre compris entre 100 et 1000 microns est suffisante pour cette application. Par suite, le procédé exposé ci-dessus est inutilement complexe et coûteux.However, in the case of the production of a composite neutron absorbing material by sintering, the creep resistance properties and the fatigue characteristics are not essential. The realization of a dispersed phase network with a mesh of diameter between 100 and 1000 microns is sufficient for this application. As a result, the above process is unnecessarily complex and expensive.
On connaît par ailleurs (FR-A-2 359 665 - C.E.A.-) un procédé de fabrication de pièces en nickel ou en alliage de nickel par métallurgie des poudres. On dépose une couche de Ni₃P sur une poudre de nickel ou d'alliage de nickel, on fritte sous charge la poudre ainsi revêtue à une température comprise entre 1000 et 1200°C sous une pression supérieure à 300 bars pendant une durée au plus égale à une heure de manière à obtenir une structure dite "en collier" correspondant à une structure hétérogène du matériau présentant de gros grains entourés et soudés entre eux par des grains finement cristallisés de dimensions inférieures.We also know (FR-A-2 359 665 - C.E.A.-) a process for manufacturing parts made of nickel or a nickel alloy by powder metallurgy. A layer of Ni₃P is deposited on a nickel or nickel alloy powder, the powder thus coated is sintered under load at a temperature between 1000 and 1200 ° C. under a pressure greater than 300 bars for a period at most equal to one hour so as to obtain a so-called "collar" structure corresponding to a heterogeneous structure of the material having large grains surrounded and welded together by finely crystallized grains of smaller dimensions.
Cependant, ce procédé n'est pas destiné à la réalisation d'un matériau neutrophage. Il n'utilise pas de particules de B₄C, qui présentent des propriétés particulièrement intéressantes du point de vue de l'absorption des neutrons, l'un des problèmes techniques à résoudre, selon l'invention, étant de faire tenir les particules de B₄C sur le matériau constituant la matrice. En outre, ce procédé ne permet pas de réaliser un matériau résistant à une atmosphère corrosive.However, this method is not intended for producing a neutron absorbing material. It does not use B₄C particles, which have particularly advantageous properties from the point of view of neutron absorption, one of the technical problems to be solved, according to the invention, being to hold the B₄C particles on the material constituting the matrix. In addition, this method does not make it possible to produce a material resistant to a corrosive atmosphere.
La présente invention a précisément pour objet un procédé de réalisation par frittage d'un matériau composite, qui permet d'obtenir de manière simple, rapide et peu coûteuse un réseau de phase dispersée présentant des caractéristiques mécaniques et chimiques qui le rendent particulièrement apte à être utilisé en tant que matériau neutrophage, en particulier dans l'industrie nucléaire. En outre, ce matériau doit présenter une bonne résistance à la corrosion.The present invention specifically relates to a process for producing by sintering a composite material, which makes it possible to obtain in a simple, rapid and inexpensive manner a dispersed phase network having mechanical and chemical characteristics which make it particularly suitable for being used as a neutron absorbing material, especially in the nuclear industry. In addition, this material must have good corrosion resistance.
Plus précisément, l'invention concerne un procédé de fabrication d'un matériau composite constitué d'un métal ou d'un alliage de ce métal constituant une matrice et d'un élément dispersoïde ou d'un composé dispersoïde combiné à ladite matrice par une dispersion de l'élément ou du composé à l'intérieur de la matrice, caractérisé en ce que :
- on conditionne le matériau de la matrice sous forme de particules sphériques d'un diamètre supérieur à 300 microns ;
- on dépose les particules de l'élément ou du composé dispersoïde sur les particules du matériau constituant la matrice, par voie humide en mélangeant la poudre de la matrice et la poudre de l'élément dispersoïde avec une quantité d'un liant organique,
- on introduit les particules de matériau constituant la matrice revêtues des particules du composé dispersoïde dans un moule présentant une cavité de forme intérieure correspondant à une forme de pièce à obtenir, la paroi interne de cette cavité étant revêtue d'une couche de verre de faible épaisseur,
- on soumet les particules du matériau constituant la matrice enrobée à un frittage par compression isostatique à chaud, lors duquel la couche de verre qui revêt la paroi interne du moule doit se remollir et épouser la forme du matériau composite en cours de densification.
- the material of the matrix is conditioned in the form of spherical particles with a diameter greater than 300 microns;
- the particles of the element or of the dispersoid compound are deposited on the particles of the material constituting the matrix, by wet method by mixing the powder of the matrix and the powder of the dispersoid element with an amount of an organic binder,
- the particles of material constituting the matrix coated with the particles of the dispersoid compound are introduced into a mold having an interior shaped cavity corresponding to a shape of part to be obtained, the internal wall of this cavity being coated with a thin glass layer ,
- the particles of the material constituting the coated matrix are subjected to sintering by hot isostatic compression, during which the layer of glass which covers the internal wall of the mold must soften and conform to the shape of the composite material being densified.
De plus l'invention concerne un matériau composite obtenu par ce procédé et conformement à la revendication 6.Furthermore, the invention relates to a composite material obtained by this process and in accordance with
D'autres caractéristiques et avantages de l'invention apparaîtront encore à la lecture de la description qui suit d'un exemple de réalisation donné à titre illustratif et nullement limitatif en référence aux figures annexées, sur lesquelles :
- la figure 1 illustre l'étape d'enrobage des particules selon le procédé de l'invention,
- la figure 2 est une vue en coupe d'un moule dans lequel les particules enrobées sont introduites,
- la figure 3 montre la déformation des particules sphériques au cours de l'opération de frittage.
- FIG. 1 illustrates the step of coating the particles according to the method of the invention,
- FIG. 2 is a sectional view of a mold into which the coated particles are introduced,
- FIG. 3 shows the deformation of the spherical particles during the sintering operation.
Le matériau composite réalisé selon le procédé de l'invention est préparé à partir de particules métalliques 2 d'un diamètre relativement important, à savoir supérieur à 300 microns. Ces particules sont réalisées en un métal, ou un alliage d'un métal et sont destinées à constituer la matrice du composite. Elles sont revêtues par un dépôt constitué de particules de la phase à disperser, cette phase devant être insoluble dans la matrice dans les conditions de pression et de température d'utilisation du matériau. Ces particules encore appelées éléments dispersoïdes sont un élément simple ou un composé. Elles sont préparées sous la forme de particules sphériques 4 de diamètre beaucoup plus faible que les particules de la matrice. Ce diamètre est de l'ordre du micron. Pour la réalisation d'un matériau composite neutrophage, on utilisera de préférence le B₄C en raison de ses bonnes propriétés d'absorption des neutrons.The composite material produced according to the method of the invention is prepared from
Le dépôt peut être obtenu par tout procédé connu à la portée de l'homme de l'art, en particulier par voie sèche ou par voie humide.The deposit can be obtained by any method known to those skilled in the art, in particular by the dry or wet method.
On peut par exemple, comme illustré sur la figure 1, déposer les particules de B₄C sur les particules de titane par dragéification par voie humide en mélangeant les particules de B₄C, les particules de titane avec un liant organique tel que de l'huile de vaseline.It is possible, for example, as illustrated in FIG. 1, to deposit the B₄C particles on the titanium particles by wet coating by mixing the B₄C particles, the titanium particles with an organic binder such as petroleum jelly. .
Les particules enrobées sont ensuite introduites dans un moule 6 (voir figure 2) présentant une cavité interne reproduisant la forme de la ou des pièces à obtenir. L'empilage compact des particules revêtues est ensuite fritté et densifié en compression isostatique à chaud sous une pression très élevée, par exemple 1000 bars. Les pièces ainsi obtenues sont ensuite retirées du moule, et séparées l'une de l'autre. Pour obtenir un matériau neutrophage ou non destiné à être mis en contact, lors de leur utilisation, avec un milieu extérieur corrosif, la compression isostatique à chaud est avantageusement réalisée à l'aide d'un moule 6 céramique dont la paroi interne 11 est en verre d'épaisseur faible. A chaud, le verre plastique épouse parfaitement la forme en cours de densification. Après refroidissement, la couche de verre se détache du moule et reste au moins partiellement solidaire de la pièce de matériau composite ; cette couche constitue ainsi une barrière efficace contre une corrosion ultérieure ou une attaque chimique due à un milieu extérieur agressif.The coated particles are then introduced into a mold 6 (see FIG. 2) having an internal cavity reproducing the shape of the part or parts to be obtained. The compact stack of coated particles is then sintered and densified under hot isostatic compression under very high pressure, for example 1000 bars. The parts thus obtained are then removed from the mold, and separated from one another. To get a neutron absorbing material or not intended to be brought into contact, during their use, with a corrosive external medium, the hot isostatic compression is advantageously carried out using a
Les avantages du procédé de l'invention qui vient d'être décrit sont les suivants :The advantages of the process of the invention which has just been described are the following:
Les particules de grand diamètre qui sont utilisées sont faciles à revêtir étant donné qu'elles présentent une surface spécifique réduite. En d'autres termes, la surface de ces particules rapportée à leur volume est plus faible que pour des particules de diamètre plus faible comme celles que l'on utilise dans les procédés de l'art antérieur.The large diameter particles which are used are easy to coat since they have a reduced specific surface. In other words, the surface of these particles relative to their volume is smaller than for particles of smaller diameter such as those which are used in the processes of the prior art.
Les particules revêtues, assemblées dans un moule présentant la forme de la pièce à réaliser, forment un empilagge compact laissant à vert (à cru) une forte porosité, de l'ordre de 30 à 50% de la densité théorique.The coated particles, assembled in a mold having the shape of the part to be produced, form a compact stack leaving green (raw) with a high porosity, of the order of 30 to 50% of the theoretical density.
La présence d'un liant organique permet de conserver une distribution homogène de la phase dispersée dans la pièce composite durant toutes les opérations de manipulation des poudres sans rique de ségrégation, c'est-à-dire sans risque de voir apparaître des zones dans lesquelles les particules de titane se séparent des particules de B₄C comme cela pourrait en effet se produire pendant la période de remplissage du moule, ce qui conduirait à l'obtention d'un matériau composite présentant des zones de fragilité.The presence of an organic binder makes it possible to maintain a homogeneous distribution of the phase dispersed in the composite part during all the powder handling operations without the risk of segregation, that is to say without the risk of seeing areas appear in which the titanium particles separate from the B₄C particles as this could indeed occur during the filling period of the mold, which would lead to the production of a composite material having zones of brittleness.
Au cours de la phase de frittage, sous l'effet de la pression isostatique, les particules sphériques se déforment et prennent la forme de polyèdres 2a, comme représenté sur la figure 3. Cet écoulement à chaud du métal au cours du corroyage conduit à l'élimination de la porosité mentionnée précédemment. Il brise localement le revêtement de particules de B₄C. Les particules de titane sont ainsi mises à nu et viennent en contact les unes avec les autres directement en certains points 12 de leur périphérie, sans interposition de composé dispersoïde entre elles. Sous l'effet de la température et de la pression se produit le corroyage, c'est-à-dire un soudage des particules de titane entre elles par formation de ponts de diffusion. Ce corroyage est nécessaire à la bonne intégrité du composite après frittage car il permet une liaison rigide des grains ou particules de titane entre elles, ce qui conduit à obtenir un matériau présentant une bonne résistance mécanique.During the sintering phase, under the effect of the isostatic pressure, the spherical particles deform and take the form of polyhedra 2a, as shown in the figure 3. This hot flow of metal during the working leads to the elimination of the porosity mentioned above. It locally breaks the coating of B₄C particles. The titanium particles are thus exposed and come into contact with each other directly at
En conséquence, le composite présente une structure qui, en dépit d'une répartition régulière des particules de composé dispersoïde entre les particules de titane, pourrait être qualifiée d'hétérogène, dans la mesure où, à certains endroits, les particules métalliques de la matrice sont directement liées les unes aux autres. Les ilôts de phase dispersée sont répartis dans les joints de polyèdres résultant de la déformation des particules métalliques sphériques.Consequently, the composite has a structure which, in spite of a regular distribution of the particles of dispersoid compound between the particles of titanium, could be qualified as heterogeneous, insofar as, in certain places, the metallic particles of the matrix are directly related to each other. The dispersed phase islands are distributed in the polyhedron joints resulting from the deformation of spherical metal particles.
On a réalisé un matériau composite neutrophage constitué d'une matrice en alliage de titane et d'une dispersion de B₄C.A neutron-absorbing composite material was made up of a titanium alloy matrix and a dispersion of B₄C.
On a mélangé pendant dix à quinze minutes 1750 g de poudre d'alliage de titane ou de titane constituée de particules sphériques fondues ou frittées de diamètre compris entre 300 et 1000 microns, avec 750 g de poudre micronique de B₄C et quelques gouttes d'huile de vaseline. La concentration en liant, à savoir l'huile de vaseline, a été réalisée de telle façon que la poudre de B₄C adhère à la surface des particules de titane sans agrégation de ces dernières.1750 g of titanium or titanium alloy powder constituted by molten or sintered spherical particles with a diameter between 300 and 1000 microns were mixed for ten to fifteen minutes with 750 g of micron B poudreC powder and a few drops of oil. petroleum jelly. The concentration of binder, namely petroleum jelly, was carried out in such a way that the B₄C powder adheres to the surface of the titanium particles without aggregation of the latter.
Les poudres ainsi revêtues sont introduites dans une enveloppe 6 métallique ou en matériau céramique présentant une ou des cavités internes 10 reproduisant la ou les pièces à fritter et dont la paroi interne 11 est en verre.The powders thus coated are introduced into a
Dans l'exemple réalisé, des sphères composites ont été moulées dans un moule en céramique formant un chapelet de sphères 10 de 14 mm de diamètre. Les moules 6 sont dégazés à une température comprise entre 100 et 300°C sous vide avant d'être scellés.In the example produced, composite spheres were molded in a ceramic mold forming a chain of
La compression isostatique à chaud est réalisée à 1000°C sous une pression de 1000 bars d'argon pendant trois heures.The hot isostatic compression is carried out at 1000 ° C. under a pressure of 1000 bars of argon for three hours.
Après compression, le moule 6 est éliminé. On obtient des sphères de matériau composite présentant une bonne résistance mécanique à l'écrasement. Le film de verre restant à la surface des sphères dudit matériau composite est une barrière efficace contre la corrosion ou contre une attaque chimique ultérieure (par exemple : acide nitrique brouillant).After compression, the
Claims (7)
- Process for the manufacture of a composite material consisting of a metal or of an alloy (2) of this metal constituting a matrix and of a dispersoid element (4) or of a dispersoid compound combined with the said matrix by a dispersion of the element or of the compound inside the matrix, characterised in that:- the material of the matrix (2) is conditioned in the form of spherical particles with a diameter greater than 300 microns;- the particles of the dispersoid element or compound (4) are deposited on the particles of the material constituting the matrix by a wet route by mixing the matrix powder and the dispersoid element powder with a quantity of an organic binder;- the particles of material constituting the matrix which are coated with the particles of the dispersoid compound are introduced into a mould (6) which has a cavity (10) of internal shape corresponding to a shape of an article to be obtained, the inner wall (11) of this cavity being coated with a thin layer of glass; and- the particles of the material constituting the coated matrix are subjected to sintering by isostatic compression with heating, during which the layer of glass which coats the inner wall of the mould must soften and adapt to the shape of the composite material being densified.
- Process according to Claim 1, characterised in that the said organic binder is vaseline oil.
- Process according to either of Claims 1 and 2, characterised in that the sintering pressure is of the order of 1,000 bars and that it is maintained for thirty minutes.
- Process according to any one of Claims 1 to 3, characterised in that the dispersoid element consists of particles of B₄C whose diameter is of the order of a micron.
- Process according to any one of Claims 1 to 4, characterised in that the mould which has a cavity (10) of internal shape corresponding to a shape of articles to be obtained is made of ceramic or of metal.
- Composite material obtained by the process according to Claim 5, characterised in that a film of glass is applied onto the outer surface of the said composite material.
- Composite material according to Claim 6, characterised in that it consists of a matrix made of titanium alloy and of a dispersion of B₄C.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR8617669 | 1986-12-17 | ||
| FR8617669A FR2608828B1 (en) | 1986-12-17 | 1986-12-17 | PROCESS FOR PRODUCING A COMPOSITE MATERIAL, IN PARTICULAR A NEUTROPHOUS COMPOSITE MATERIAL |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0275746A1 EP0275746A1 (en) | 1988-07-27 |
| EP0275746B1 true EP0275746B1 (en) | 1992-02-26 |
Family
ID=9342003
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP87402840A Expired - Lifetime EP0275746B1 (en) | 1986-12-17 | 1987-12-14 | Method to produce a composite material, particularly a neutron absorbing composite material |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0275746B1 (en) |
| DE (1) | DE3776879D1 (en) |
| FR (1) | FR2608828B1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2646007B1 (en) * | 1989-04-18 | 1994-04-01 | Tecphy | PROCESS FOR PRODUCING A NEUTRONIC RADIATION ABSORBING PRODUCT, PRODUCT THUS PRODUCED AND ITS APPLICATIONS |
| GB9417175D0 (en) * | 1994-08-25 | 1994-10-12 | Hare John T | Radiation shield |
| CN113345615B (en) * | 2021-05-31 | 2022-12-27 | 中国工程物理研究院材料研究所 | Paraffin/boron carbide neutron protection composite material and preparation method thereof |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3167428A (en) * | 1961-12-13 | 1965-01-26 | Cons Astronautics Inc | Titanium powder metallurgy |
| FR2359665B1 (en) * | 1976-07-29 | 1980-12-19 | Commissariat Energie Atomique | PROCESS FOR MANUFACTURING NICKEL OR NICKEL ALLOY PARTS BY POWDER METALLURGY |
| FI793353A (en) * | 1979-02-21 | 1980-08-22 | Carborundum Co | NEUTRON ABSORBER ELEMENT OCH FOERFARANDE FOER DESS FRAMSTAELLNING |
| JPS5738896A (en) * | 1980-08-15 | 1982-03-03 | Sumitomo Chem Co Ltd | Composite binder composition for powder molding |
| DE3040771A1 (en) * | 1980-10-29 | 1982-05-27 | Elektroschmelzwerk Kempten GmbH, 8000 München | METHOD FOR THE PRODUCTION OF PRACTICALLY PORE-FREE, POLYCRYSTALLINE MOLDED BODIES BY ISOSTATIC HOT PRESSING IN GLASHUELLES |
-
1986
- 1986-12-17 FR FR8617669A patent/FR2608828B1/en not_active Expired - Fee Related
-
1987
- 1987-12-14 DE DE8787402840T patent/DE3776879D1/en not_active Expired - Lifetime
- 1987-12-14 EP EP87402840A patent/EP0275746B1/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| DE3776879D1 (en) | 1992-04-02 |
| FR2608828B1 (en) | 1993-09-10 |
| EP0275746A1 (en) | 1988-07-27 |
| FR2608828A1 (en) | 1988-06-24 |
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