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
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/12—Both compacting and sintering
  • B22F3/14—Both compacting and sintering simultaneously
  • B22F3/15—Hot isostatic pressing
  • B22F3/156—Hot isostatic pressing by a pressure medium in liquid or powder form
• • 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
  • B22F1/052—Metallic powder characterised by the size or surface area of the particles characterised by a mixture of particles of different sizes or by the particle size distribution
• • 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
  • B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
  • B22F10/10—Formation of a green body
• • 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
  • B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
  • B22F10/60—Treatment of workpieces or articles after build-up
  • B22F10/64—Treatment of workpieces or articles after build-up by thermal means
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y40/00—Auxiliary operations or equipment, e.g. for material handling
  • B33Y40/20—Post-treatment, e.g. curing, coating or polishing
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
  • C04B35/63—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B using additives specially adapted for forming the products, e.g.. binder binders
  • C04B35/638—Removal thereof
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/64—Burning or sintering processes
  • C04B35/645—Pressure sintering
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/653—Processes involving a melting step
• • 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
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/02—Compacting only
  • B22F3/03—Press-moulding apparatus therefor
  • B22F2003/033—Press-moulding apparatus therefor with multiple punches working in the same direction
• • 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
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/10—Sintering only
  • B22F3/105—Sintering only by using electric current other than for infrared radiant energy, laser radiation or plasma ; by ultrasonic bonding
  • B22F2003/1051—Sintering only by using electric current other than for infrared radiant energy, laser radiation or plasma ; by ultrasonic bonding by electric discharge
• • 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
  • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
• • 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
  • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
  • B22F2998/10—Processes characterised by the sequence of their steps
• • 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
  • B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy
• • 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
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/02—Compacting only
  • B22F3/03—Press-moulding apparatus therefor
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
  • C04B2235/54—Particle size related information
  • C04B2235/5418—Particle size related information expressed by the size of the particles or aggregates thereof
  • C04B2235/5436—Particle size related information expressed by the size of the particles or aggregates thereof micrometer sized, i.e. from 1 to 100 micron
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
  • C04B2235/54—Particle size related information
  • C04B2235/5463—Particle size distributions
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/60—Aspects relating to the preparation, properties or mechanical treatment of green bodies or pre-forms
  • C04B2235/602—Making the green bodies or pre-forms by moulding
  • C04B2235/6026—Computer aided shaping, e.g. rapid prototyping
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/65—Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes
  • C04B2235/66—Specific sintering techniques, e.g. centrifugal sintering
  • C04B2235/666—Applying a current during sintering, e.g. plasma sintering [SPS], electrical resistance heating or pulse electric current sintering [PECS]
• • 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
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P10/00—Technologies related to metal processing
  • Y02P10/25—Process efficiency

Definitions

• the invention relates to a process for manufacturing a part close to the dimensions (Near Net Shape or NNS) of complex shape by sintering under load from a preform produced according to a first method of manufacture, for example by an additive or molding technique.
• NNS Near Net Shape
• Sintering corresponds to the thermal consolidation of a pulverulent material of its constituents. It is one of the most delicate and often the most expensive operations during the preparation of ceramics.
• the microstructure is put in place, by transport of matter between grains, in order to minimize excess interface energies, which is generally accompanied by a reduction in porosity.
• the latter is manifested macroscopically by a shrinkage in relation to the “raw” part.
• the raw material of a sintered component is generally a metal or ceramic powder. The characteristics of the part to be obtained determine the chemical composition of the powder.
• hot isostatic pressing is a method of producing a high quality metal component such that it can be used in many applications, for example aerospace.
• HIP is a heat treatment method that uses high temperatures and pressures to sinter particles of material, resulting in a component with improved structural properties on forged or cast objects.
• the HIP process subjects a material, either in solid or powder form, to both elevated temperature and isostatic gas pressure in a high pressure containment vessel.
• the material can for example be a metal powder.
• HIP can be used to densify existing metal components with internal voids, or to join two components together.
• Metal powders can be either pure metal powders (iron, copper) or alloy powders (bronze, brass, steel, etc.). The different nature of the powders (sponge, irregular, spherical, laminar), gives different properties to the component.
• CIC FH I P hot isostatic compaction
• the Chinese patent application CN102189261 a process for densifying a type of porous product consisting of placing a porous product in a sheath, the sheath and endpiece junction being implemented by welding and sealing before applying isostatic pressing.
• This solution involves the use of a silica-type powder which considerably limits the type of materials that can be used, and leads to a porous part to be densified without in-situ extraction of the binder contained in the part produced.
• Patent application WO2011030815 relates to a process for producing an electrically conductive molded object, which involves a step of sintering a premolded object, which is an object produced by molding a first electrically conductive powder, by a process flash sintering to form the electrically conductive molded object.
• the precast object is sintered by applying a DC pulse current to the precast object while applying pressure to the precast object by a second electrically conductive powder.
• Patent application DE2219410 relates to a process for the manufacture of molded parts pressed from powder, in particular from a high-strength refractory material down to an almost theoretical density by preforming a part pressed from a material powder having voids, by enclosing the molded part in a loose mass of pressure transmitting powder which, in a mold, by applying unidirectional pressure to the pressure transferring powder in the mold to further compress the molded part and , while simultaneously heating the body to at least the compaction temperature of the body, preferably in a controlled atmosphere, in which the temperature and/or pressure is increased to the densification temperature of the refractory material, thereby virtually eliminating all voids in the compressed form.
• the present invention relates, in its most general sense, to a process for manufacturing a part by sintering under load, characterized in that it comprises:
• a second step of heat treatment under pressure of said solid and non-porous preform consisting of: • Prepare a thermal sintering tool with the following steps: o Installation of a lower piston in a graphite matrix, o Insertion into said lower piston of a quantity of a first reusable compaction powder, with a particle size greater than the particle size of said bonded particles of the preform and having a melting temperature higher than the sintering temperature of said particles of said preform o Positioning of said solid and non-porous preform directly above said bed of compacting powder o Insertion of a second quantity a second reusable compacting powder, with a particle size greater than the particle size of said bonded particles of the preform and reusable, directly on said preform o Positioning of the upper piston in the graphite matrix,
• the binder is not removed before the SPS step, and therefore the part has a non-porous homogeneous state, the interstice between the grains being filled by the bonding matrix , which is then extracted during the sintering step, and not before the heat treatment step under pressure jointly ensures the effect of grain surface welding and densification.
• said preform is manufactured by additive manufacturing of a pulverulent material having a particle size D50 of between 1 and 10 miti.
• said sintering powder has a D50 particle size of between 15 and 30 miti.
• said first and second compacting powders are identical.
• said compacting powder or powders are non-metallic powders.
• the said compacting powder or powders are carbon graphite powders or an oxide ceramic.
• Figure 1 shows a schematic view of a tool for the implementation of the invention
• Figure 2 shows a partial schematic view of the tooling during the densification phase
• Figure 3 shows a schematic view of the decapsulation of the sintered part.
• the process that is the subject of the invention is broken down into two phases: the preparation of a massive, non-porous preform from metal or ceramic particles held together by a binder the positioning of the preform in a volume of compaction powder placed between two pistons
• a post-treatment intended to increase the rate of densification and simultaneously the removal of the binder by the application of pressure on the pistons and heating to the sintering temperature to cause the debinding, the binder diffusing into the compacting powder as well as the simultaneous sintering of the metallic or ceramic particles of the preform.
• the process is similar to a Hot Isostatic Pressing (HIP) process which makes it possible not to use special tools to apply the pressure although the load is not applied in a perfectly isotropic manner, more than to an SPS process which provides a perfectly uniaxial action.
• HIP Hot Isostatic Pressing
• the preform is placed in an enclosure into which an inert gas is injected (argon, nitrogen) under an applied pressure of approximately 100 MPa, homogeneously in all directions including at incoming angles.
• an inert gas argon, nitrogen
• it is not an inert gas which transmits the pressure, but a volume of powder which transmits the pressure and the heat to the preform.
• the first step of the invention consists in manufacturing a preform made up of metallic or ceramic particles or more generally of a sinterable material. These particles must have a D50 particle size of less than 15 miti, which means that half of the grains are less than 15 miti in section, and half more than 15 miti. Preferably, the particle size dispersion is low and less than 1% of the particles have a section different from ⁇ 10% of the median section.
• the preparation of a preform can be carried out in different ways.
• One way is to manufacture a part by a “Bound Metal Deposition” type process developed for metal using the polymer melt deposition process (FDM or FFF) or by laser sintering, from a wire, bars or pellets that will be extruded. These are composed of metallic powder and of a binder.
• the “binder jetting” type process is less appropriate because the parts produced by “binder jetting” at the raw stage are relatively dense.
• the metal powder is, for example, 316L steel, the sintering temperature of which is greater than 600° C. with a mass percentage of binder of the order of 15%, in the form of metal wire with a binder envelope.
• the part obtained is a solid, non-porous part, formed by a combination of ceramic or metal and plastic.
• the manufacture of the preform can also be carried out by a laser process by bonding grains in a fusible phase (two-phase material) using a powder coated with the fusible binder. During the laser transfer, the binder occupies the interstice between the metallurgical grains to form a massive part without porosity.
• the fusible binder is generally made up of polymers.
• the major drawback of these methods is that the object produced is not of relevant quality and that the functional tests cannot be carried out under real conditions of use.
• the preform has a geometry taking into account the deformation resulting from the sintering step, by mathematical modeling or by empirical adjustments.
• the densification step consists of introducing the preform into a bed of powder with a particle size greater than that of the powders used for the manufacture of the preform.
• This powder completely surrounds the preform; it is subjected to pressure under the effect of two opposing heated pistons.
• the powder transmits heat to the preform, causing the binder to carbonize and the preform powder to sinter. Any gaseous effluent produced by the heating of the binder is evacuated through the grains of the powder bed surrounding the preform.
• the preparation of the sintering tool comprises the following steps:
• Insertion of a quantity of compacting powder of a first type The chemical nature, the particle size and the quantity of the powder are chosen by following the chemical nature of the powders the preform, its particle size, its geometric complexity, ...
• the properties of this powder can be identical in all respects to the first powder bed, but can also differ (in particular the quantity and the granulometry);
• the part is positioned on the compacting powder bed in such a way as to optimize densification while reducing shrinkage in certain directions.
• a deformation study and a main axis of pressing is identified by modeling or an empirical approach. Optimization of positioning is carried out either by numerical study, but most often empirically.
• the quantity of powder is chosen so as to absorb by capillarity the gaseous/liquid phases of binder forming during this sintering step.
• the compaction powder allows the load transfer of the compression pistons while accommodating the shape of the part.
• the characteristics of the compaction powder are such that the sintering temperature is significantly higher than that of the printed powder constituting the part to be densified or else chemically compatible and allowing the use of shake-out processes after densification.
• the compaction/sintering powder ensures that the pressure stresses apply quasi-isotropically.
• the part is sized (local extra thickness) in order to be in-fine “near net shape” (close to the final shape), which limits the machining finishing steps as much as possible to obtain the shape in a “net shape” state. ".
• the part can be hollow and the inside is also filled with sintering powder.
• the tool consists of an upper piston (10) and a lower piston (20) actuated in opposite directions along a longitudinal axis (1) by cylinders (11, 21) exerting an opposing thrust on the pistons (10, 20) .
• the pistons (10, 20) are made of an electrically conductive material and are connected to a pulsed current generator (30).
• the piston (10) is extended by a connecting block (12) called “spacer” also electrically conductive and having an upper die (13) defining with a lower die (23) a treatment enclosure (15).
• the lower die (23) forms the end of a connecting block (22) called a “spacer”, which is also electrically conductive and extends the piston (20).
• the part (16) obtained by additive manufacturing is placed in this enclosure (15), on a layer (17) of compacting powder then covered with a second layer (18) of compacting powder.
• the compacting powder will for example be graphite carbon or an oxide ceramic.
• the experimental results lead to a preferential use of a graphite compaction powder and on green parts produced exclusively by additive manufacturing of the fused wire deposition type (in English FDM Fused deposition modeling).
• the nature of the materials is advantageously chosen from the following: inco 625, 315L, 17-4-ph, H13, TiAl, alumina, zirconia and SiC.
• the invention is particularly advantageous through the reuse of the graphite forming the compaction powder.
• the production process provides for a thermal cycle presenting, after the compaction stage, an in-situ debinding step allowing the binder not to flash off, thus protecting the part.
• Differential compaction of the graphite powder is carried out in order to promote good sintering of the part, which makes it possible to have a forced deformation in a single direction in space, facilitating the retro-dimensioning of green parts.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Ceramic Engineering (AREA)
• Materials Engineering (AREA)
• Inorganic Chemistry (AREA)
• Structural Engineering (AREA)
• Organic Chemistry (AREA)
• Mechanical Engineering (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Powder Metallurgy (AREA)

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• 2021
  • 2021-03-02 FR FR2101992A patent/FR3120320A1/fr active Pending
• 2022
  • 2022-03-02 WO PCT/FR2022/050370 patent/WO2022185009A1/fr active Application Filing
  • 2022-03-02 EP EP22711275.2A patent/EP4301531A1/de active Pending

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