Patent Application
20240335875
The invention relates to the manufacture of aeronautical parts, in particular blades or aeronautical turbomachine rectifiers, by solid-phase densification methods. More precisely, the invention relates to the counter-forms used in the manufacture of these aeronautical parts, to a process for manufacturing such a counter-form, and to a process for manufacturing such an aeronautical part.
Metal aeronautical parts, in particular turbine blades or rectifiers, are generally manufactured with alloys based on nickel, titanium, or titanium aluminide. In order to limit the risk of contamination of the materials constituting the parts related to the use of liquid phases during foundry manufacturing processes, solid-phase densification manufacturing processes can be used.
Such solid-phase densification manufacturing processes comprise, for example, sintering under load, such as SPS (“Spark Plasma Sintering”) or HIP (“Hot Isostatic Pressing”), or the injection of a mixture of metal powder and a thermoplastic polymer (called the MIM process for “Metal Injection Molding”).
SPS sintering is a sintering process using the Joule effect to heat the pre-compacted powder, constituting the part to be manufactured (in the present application, a powder based on nickel, titanium, or titanium aluminide) in a hollow graphite tooling between two electrodes, between which a pulsed current is applied, under an inert atmosphere or under vacuum, the tooling being subjected to a uniaxial pressure, for example under the action of a hydraulic press. Joule effect heating of the powder thus allows the densification of the part.
In the case of HIP sintering, a preform of the part to be manufactured is placed in a container evacuated to a vacuum before being hermetically sealed. A homogeneous pressure in all directions is thus applied to the part, via the container, by injecting a neutral gas under pressure (for example argon or nitrogen) into the enclosure of the container.
Furthermore, during mixing by powder injection, known as the MIM process, a powder constituting the material to be manufactured is mixed with a polymer binder. The mixture obtained, called “feedstock”, is then injected into a tooling to form the part to be manufactured. The binder is then removed during a debinding process. A sintering operation on the part obtained can then be carried out.
These types of processes allow to manufacture demoldable parts, such as certain turbine blades. However, these processes have certain disadvantages. Indeed, for SPS sintering for example, after densification at high temperature, the current is cut off and the part cools. During this cooling phase, the densified part is still contained by the graphite mold which gave it its shape, and undergoes contraction related to its coefficient of thermal expansion (approximately 10-12×10−6/° C. for metal parts). However, taking into account its coefficient of thermal expansion (approximately 2-3×10−6/° C.), graphite tooling deforms very little during cooling, which generates differential expansions and stresses which can lead either to the breakage of toolings or their premature wear, or to the breakage of the densified part. This is particularly the case for the geometries of blades with sealing lips and roots, or else rectifiers.
To overcome this limitation, it is known to use molds called “drawer” molds, having different parts arranged with each other so as to allow the densification of the part following a predefined shape, but while allowing the mold to retract when it cools. The mechanical stresses applied by the part during its cooling generate in particular a movement of the different sections of the mold. Although this technique has advantages, it can cause local burrs, and requires a very strict adjustment of the mold parts which is difficult to maintain due to its repeated use at temperature and under load.
To overcome these disadvantages, it is also known to use counter-forms corresponding to the negative of the part to be manufactured, allowing to produce complex parts, these counter-forms themselves being disposed in the aforementioned graphite tooling. A process using such counter-forms conventionally comprises the manufacture of a counter-form by additive manufacturing, the partial sintering of the counter-form to give it rigidity, the filling of the counter-form with a powder to be densified, the joint SPS sintering of the material constituting the counter-form and the powder present inside the latter, and finally the shakeout of the counter-form to release the sintered part.
This process nevertheless involves various disadvantages. On the one hand, the materials used for the counter-forms are ceramics, or a composite thereof, such as zirconia stabilized with yttrium oxide (YSZ), zirconia reinforced with alumina (ATZ), or alumina reinforced with zirconia (ZTA). These materials have the disadvantage of not being electrical conductors, which, particularly in the context of SPS sintering, limits the generation of the Joule effect in the powder to be sintered, and can lead to local densification defects due to inhomogeneity of the induced thermal field.
On the other hand, the titanium or titanium aluminide alloys used to manufacture the blades or the rectifiers are conventionally sintered by SPS at temperatures above 1350° C. However, at these temperatures, the above ceramic materials used for the counter-forms have a density greater than 80%, which makes their shakeout difficult and requires a specific step involving chemical or mechanical shakeout, potentially harmful for the part manufactured subsequently and for the environment, the counter-form cannot be recycled.
Furthermore, the materials used for the part to be manufactured and the counter-form have different thermal expansion coefficients, which can cause deformation of the part in the finest areas such as the trailing edges, the breakage of the parts, or lead to the recrystallization of certain areas under stress, inducing mechanical reductions.
There is therefore a need for a solution allowing to at least partially overcome the aforementioned disadvantages.
The present disclosure relates to a counter-form for producing metal aeronautical parts, in particular a turbine part by solid-phase densification, comprising a composite material comprising, on the one hand, a first phase having formula Mn+1AlCn, where n=1 to 3 and M is a transition metal selected from the group consisting of titanium and/or molybdenum and/or niobium and/or chromium, and, on the other hand, the composite material comprising a second phase having formula Al4C3.
It is understood that the first phase is of the “MAX phase” type, crystal structure of generic formula Mn+1AXn, combining characteristics of both metals and ceramics, and having in particular good thermal and electrical conductivity, good machinability, as well as damage tolerance and oxidation resistance at high temperatures.
In this disclosure, the use of aluminum on site A and carbon on site X ensures good chemical compatibility with the Al4C3 phase. Moreover, the use of aluminum on site A ensures the formation of a protective alumina layer by oxidation of the counter-form. In addition, the use of carbon on site X is advantageous in that it does not have the risk of contaminating the materials present, nor of reacting negatively with the Al4C3 phase, unlike nitrogen.
Moreover, the titanium or chromium, used on site M, have melting temperatures higher than the temperatures used during the sintering of the part to be manufactured, allowing their structure and stability to be preserved during sintering. Furthermore, they have thermal expansion coefficients compatible with those of the materials to be densified, in particular alloys based on nickel, titanium, or titanium aluminide, and good thermal conductivity.
Furthermore, the association of this first phase with a second phase having formula Al4C3 is particularly advantageous. Indeed, aluminum carbide (Al4C3) is an inorganic compound, whose melting temperature is very high (2200° C.), and which can easily hydrolyze at room temperature, in the presence of an atmosphere rich in water. Thus, the composite material used for the counter-form in this disclosure integrates this second phase of aluminum carbide into the grain boundaries of the first phase. This makes the composite material particularly reactive to atmospheres containing water. The degradation of aluminum carbide is accompanied by a variation in volume and the release of gas, capable of fragmenting the grain boundary and propagating cracks in the first initial phase. It is thus possible to propagate the hydrolysis phenomenon over relatively large distances, and thus facilitate the fragmentation and shakeout of the counter-form. In other words, the composite material forming the counter-form can be dense and massive initially, and be reduced to powder by hydrolysis.
On the other hand, the chemical gradient between the aluminum carbide and the first phase containing aluminum and carbon is very limited, which allows to limit the interdiffusion between the different chemical elements during the steps of shaping the counter-form and of casting. Furthermore, once the counter-form has been shaken out, a fragmented material, composed of grains from the first phase and hydrated aluminum, can be recovered. After drying, this material can be “recharged” with Al4C3 and reused to manufacture new counter-forms.
The composite material of the counter-form according to the present disclosure thus combines the aforementioned advantages related to the first phase, with the use of a second phase having formula Al4C3, allowing the production of parts of complex shapes without having to resort to complex graphite toolings, while allowing easy and rapid shakeout of the counter-form, not requiring potentially harmful chemical solutions to the subsequently manufactured part and to the environment, and which can be recycled.
In certain embodiments, the first phase is of one of the formulas among Cr2AlC, Ti3AlC2, Ti2AlC, Nb4AlC3, Nb2AlC or Mo2TiAlC2.
These phases have good chemical compatibility with the second phase Al4C3 and allow to obtain a thermodynamically stable composite at high temperatures, during the sintering phase. The phases Cr2AlC, TisAlC2, Ti2AlC also have the advantage of covering the ranges of densification temperatures and thermal expansion coefficients of the materials considered and used to manufacture the part. Furthermore, the phases Cr2AlC, TisAlC2, Ti2AlC are alumina-forming. The other phases are not alumina-forming, it is preferable to add a coating allowing the formation of a protective layer. This addition is however not essential, other oxides having a function similar to alumina, although less adherent than the latter, can be formed on the counter-form when it is subjected to an oxidation step.
In certain embodiments, the composite material comprises between 1 and 50% of second phase by volume of the composite material, preferably between 1 and 20%. These values allow to ensure the fragmentation of the composite material by hydrolysis, while leaving a sufficient volume of first phase in the composite material, allowing to maintain the technical advantages related to this first phase. In addition, this Al4C3 phase fraction ensures the chemical stability of the material at high temperature, while allowing to induce a hydrolysis phenomenon facilitating shakeout.
In certain embodiments, an internal surface of the counter-form is covered by a layer of alumina.
Degradation of the counter-form, by hydrolysis of the aluminum carbide in an atmosphere containing water, must only take place when the counter-form is shaken out. Thus, the presence of an adherent and dense alumina layer on the internal surface of the counter-form allows to protect the composite material from degradation during the other steps for manufacturing a part preceding the shakeout of the counter-form.
In certain embodiments, the alumina layer has a thickness comprised between 1 and 50 μm. This thickness ensures the protection of the counter-form during the manufacturing of a part. More precisely, the alumina layer thus formed is thin enough to have no impact on the mechanical shrinkage of the part during cooling, but chemically isolates the powder and the counter-form.
The present disclosure also relates to a process for manufacturing a counter-form for producing a hollow metal aeronautical part, in particular a turbine part by solid-phase densification, the counter-form comprising a composite material comprising, on the one hand, a first phase having formula Mn+1AlCn, where n=1 to 3 and M is a transition metal selected from the group consisting of titanium and/or niobium and/or molybdenum and/or chromium, the composite material comprising, on the other hand, a second phase having formula Al4C3, the counter-form being obtained by a powder metallurgy process comprising a mixing step in which powders allowing to obtain the composite material are mixed, and a shaping step.
The mixture of powders allowing to obtain the first phase may in particular comprise the mixture of pure powders of carbon, aluminum, titanium and/or chromium, and/or chrome carbide, and/or chromium carbide, and/or titanium carbide, and/or aluminum carbide. In other words, the composite material constituting the counter-form is obtained by reacting the different powders of the constituent elements of this material at high temperature. This process has the advantage of involving, in the development of the composite material, the Al4C3 phase, allowing to provide the necessary Al and C elements, thus providing the aforementioned advantages.
Moreover, the shaping step can comprise the injection of a binder onto a powder (called “binder jetting”), the injection of a mixture of metal powder and a thermoplastic polymer (or MIM process for “Metal Injection Molding”) or any other suitable known 3D printing process, preferably followed by sintering, or sintering under load called “Spark Plasma Sintering” (or SPS sintering), for example.
In certain embodiments, the mixing step comprises mixing the pure powders constituting the first phase so as to obtain the first phase in powder form, then mixing said first phase in powder form with a powder of Al4C3 so as to obtain the second phase.
In other words, pure powders of carbon, aluminum, titanium and/or chrome carbide, and/or chromium carbide, and/or titanium carbide, and/or aluminum carbide for example are mixed first, so as to obtain the first phase initially, then the first phase obtained is mixed with a carbide powder of aluminum in a second step, so as to obtain the second phase. This allows to improve control of the proportions of each phase.
In certain embodiments, the mixing step comprises mixing pure powders constituting the first phase with an excess Al4C3 powder so as to form the composite material in one operation.
In other words, according to this configuration, the mixing of the powders is not carried out in two stages (manufacturing the first phase initially, then mixing with an aluminum carbide powder), but the aforementioned pure powders are mixed in the same operation with an excess of Al4C3 powder, that is to say in over-stoichiometry, thus allowing the formation of the composite material “in situ”. The fact of reacting the Al4C3 powder in over-stoichiometry with respect to the first desired phase allows to maintain a controlled volume fraction of this phase in the final material.
In certain embodiments, during the step of shaping the counter-form, a supply channel configured to allow the supply of powder constituting the part to be manufactured, is provided in the counter-form.
In others, when shaping the counter-form by one of the 3D printing techniques mentioned above, a supply channel is provided in the structure of the counter-form, so as to fluidly communicate the internal cavity of the counter-form forming the negative of the part to be manufactured, with the exterior of the counter-form. This channel facilitates the supply of powder of the material constituting the part to be manufactured and to be densified.
In certain embodiments, the first phase is of formula Cr2AlC, TisAlC2 or Ti2AlC, the process comprising, after the step of shaping the counter-form, an oxidation step allowing the formation of a layer of alumina on an internal surface of the counter-form.
As mentioned previously, the phases of formula Cr2AlC, TisAlC2 or Ti2AlC are alumina-forming, and thus allow the formation of a layer of alumina by simple oxidation of the counter-form, without requiring the addition of a complex multi-layer coating allowing the formation of this protective layer. This oxidation step allows to produce an adherent and dense layer of alumina on a wall of the internal cavity of the counter-form forming the negative of the part to be manufactured, able to protect the composite material, to further improve the shakeout of the densified part and to limit the risks of interdiffusion between the densified powder and the composite material constituting the counter-form. It should also be noted that since the subsequent densification step is carried out under vacuum, the latter does not pose any particular problem with regard to the composite material.
In certain embodiments, the oxidation step is carried out by placing the counter-form in an enclosure under air comprised between 1000° C. and 1400° C.
The present disclosure also relates to a process for producing a metal aeronautical part, in particular a turbine part by solid-phase densification, using a counter-form obtained by a process according to any of the preceding embodiments, the process comprising, after steps of filling the counter-form with a powder constituting the part to be manufactured and densifying said powder in the counter-form, a step of shaking the counter-form out by steaming.
In other words, after densification of the powder by SPS sintering, for example, in the counter-form, the assembly is disposed in a device, for example an oven, preferably with controlled humidity. As mentioned previously, the presence of the Al4C3 phase between the grain boundaries allows, in water-laden air, the disintegration of the core of the counter-form. This makes it easier to shake out and therefore unmold the part, while avoiding the use of chemical solutions, such as acids, which are potentially harmful to the manufactured part.
In certain embodiments, the process comprises, after the shakeout step, a recovery step, in which the material shaken out by steaming is recovered so as to be reused for the manufacture of another counter-form starting from the mixing step.
In other words, once the degradation of the counter-form has been carried out, a fragmented material composed of grains from the first phase and hydrated aluminum can be recovered. After drying, this material can be “recharged” with Al4C3 during the mixing step and thus be reused to manufacture new counter-forms. It is thus possible to recycle the counter-form shaken out, thus allowing to respond at least partially to the aforementioned environmental issues.
The invention and its advantages will be better understood upon reading the detailed description given below of different embodiments of the invention given by way of non-limiting examples. This description refers to the pages of appended figures, on which:
Such a blade is obtained, according to the present disclosure, by densification of a powder of the material constituting the blade, in particular alloys based on nickel (Ni), titanium (Ti), or titanium aluminide (TiAl), in a counter-form corresponding to the negative of the part to be manufactured, that is to say of the blade 10 in the present example.
Such a counter-form 1, in accordance with the present disclosure, is shown in perspective in
A passage 9a, 9b is also provided in each section 1a, 1b respectively of the counter-form 1 so as to form a supply channel 9 in the counter-form 1 after assembly of the two sections 1a and 1b, and to allow the supply of the aforementioned powder constituting the blade to be manufactured, when the sections 1a and 1b are assembled.
Moreover, the counter-form 1 comprises a composite material allowing in particular to facilitate its elimination, during the shakeout step described subsequently.
Indeed, the composite material comprises two phases: a first phase called “MAX phase”, and a second phase having formula Al4C3, in other words aluminum carbide.
The MAX phases are materials called stoichiometric materials, known per se, of formula: Mn+1AXn, with n=1 to 3, M is a transition metal, A an element from the group A and X carbon and/or nitrogen.
In this disclosure, the element used in group A is aluminum (Al) in order to ensure the formation of an alumina layer when alumina-forming phases are used. The element used at site X is carbon (C). Indeed, the phases containing nitrogen (N) often have lower melting temperatures than their carbon-containing counterparts and chemical compatibility with the Al4C3 phase is not assured. Finally, the element used on site M is determined in such a way that the melting temperature and the thermal expansion coefficient of the phases MAX considered are compatible with the constituent materials of the part to be sintered, in particular nickel (Ni) based alloys, having a thermal expansion coefficient comprised between 14 and 16×10−6/° C., titanium (Ti), having a thermal expansion coefficient comprised between 10 and 13×10−6/° C., or titanium aluminide (TiAl), having a thermal expansion coefficient comprised between 10 and 13×10−6/° C. The sintering temperatures of these materials are also higher than 1350° C.
Thus, in the application of this disclosure, the first phases retained can be of formula Cr2AlC, having a melting temperature greater than 1500° C. and a thermal expansion coefficient of approximately 13×10−6/° C., TisAlC2 having a melting temperature greater than 1550° C. and a thermal expansion coefficient comprised between 9 and 12×10−6/° C., or Ti2AlC having a melting temperature greater than 1550° C. and a thermal expansion coefficient comprised between 7 and 10×10−6/° C.
The second phase having formula Al4C3 is a known carbide whose melting temperature is very high (2200° C.). It is also alumina-forming at high temperature. However, the particularly advantageous property in the context of the invention is the ease that this phase has in hydrolyzing at room temperature in the presence of a water-rich atmosphere. The decomposition of this phase follows the following reaction:
Al4C3+12H2O→4Al(OH)3+3CH4
This reaction can be catalyzed by optimizing the humidity level but also the temperature.
Thus, taking into account the presence of the second phase having formula Al4C3, between the grain boundaries of the first phase, the counter-form 1 comprising this composite material can be easily eliminated by being degraded by hydrolysis, resulting from the manufacturing process of the blade or the rectifier.
In this regard, a first example of a blade manufacturing process according to the present disclosure is a process by sintering under load, called SPS sintering (for “Spark Plasma Sintering”) in the remainder of the description. The different steps of this process, according to a first embodiment, are presented in
The first step S100 of this process consists of manufacturing the counter-form 1 described above, in one or two sections.
In accordance with this disclosure, the step S100 for manufacturing the counter-form 1 is divided into several steps. Firstly, metal powders are mixed together, so as to obtain a composite powder comprising the first and second phases (step S110). According to the first embodiment, pure powders of aluminum (Al), carbon (C), chromium (Cr) and/or titanium (Ti), and/or chrome carbide (CrC), and/or chromium carbide (Cr7C3), and/or titanium carbide (TiC) are mixed with an excess aluminum carbide Al4C3 powder, so as to form in situ a composite material comprising the first phase and the second phase, such that the second phase represents between 1 and 50%, preferably between 1 and 20% of the total volume of the composite material.
Once the mixing step has been carried out, the counter-form 1 is shaped (step S120), so that the latter takes the desired shape. This step can be carried out by various known processes such as the injection of a binder onto a powder (called “binder jetting”), the injection of a mixture of metal powder and a thermoplastic polymer (or process MIM for “Metal Injection Molding”) or any other suitable known 3D printing process, preferably followed by sintering, or SPS sintering, for example, or any other suitable known process, or a combination of these different processes. During this shaping step, in particular 3D printing by one of the aforementioned techniques, a supply channel 9 is provided, allowing the subsequent injection of metal powder.
Then, a step of forming an alumina layer, allowing to form a protective alumina layer with a thickness comprised between 1 and 50 μm can be carried out (step S130). This step is carried out by oxidizing the counter-form 1 by bringing the latter to a temperature comprised between 100° and 1400° C. This step is made possible by the fact that the phases of formula Cr2AlC, TisAlC2 or Ti2AlC are alumina-forming.
The counter-form 1 thus manufactured in step S100, and comprising the cavity described above corresponding to the negative of the blade, is then filled with a powder constituting the blade to be manufactured (step S200), in particular a powder based on titanium (Ti), a superalloy based on nickel (Ni), or an intermetallic alloy such as titanium aluminide (TiAl), via the supply channel 9. An ultrasound table can be used to facilitate the flow of the powder into the counter-form and its filling.
It will be noted that for the densification of materials based on nickel, the use of a first phase having formula Cr2AlC is to be preferred, and for the densification of materials based on titanium aluminide or titanium, the use of a first phase having formula Ti2AlC or TisAlC2 is to be preferred. These choices are based on the compatibilities of these different materials in terms of thermal expansion, but also chemical compatibility between the first phase and the alloy to be densified. Indeed, titanium has a greater risk of diffusing at high temperatures with nickel, and chromium has the risk of forming weakening phases with titanium.
The counter-form 1 containing the powder to be densified is then placed in a tooling (not shown), which is preferably made of graphite, configured to carry out SPS sintering (step S300).
SPS sintering is then carried out (step S400). During SPS sintering, the counter-form 1 is disposed in a press exerting axial pressure on the counter-form 1. A pulsed current is then applied to the counter-form 1, so as to heat the powder present therein by Joule effect, allowing the densification of the powder.
When the densification of the part is completed, the counter-form 1 is extracted from the graphite tooling, and eliminated by shakeout in order to obtain the final part (step S500). Step S500 of shaking the counter-form 1 out can be carried out by disposing the assembly in an oven with controlled humidity (relative humidity RH>50%) or preferably in a steam autoclave, at temperatures comprised between 10° and 180° C., and pressures comprised between 6 and 12 bars. The application of pressure allows to accelerate the shakeout kinetics while facilitating access of vapors to the thin sections. This step allows the disintegration of the counter-form 1, taking into account the presence of the second phase having formula Al4C3 between the grain boundaries of the first phase. A step of cleaning and finishing the blade obtained can also be carried out.
Finally, the shakeout step S500 can be followed by a recovery (step S600), or recycling step, in which the composite material shaken out by steaming, then in powder form, is recovered so as to be reused for the manufacture of another counter-form 1, starting from the mixing step S110. More precisely, once the degradation of counter-form 1 has been carried out, a fragmented material composed of grains from the first phase and hydrated aluminum is recovered. After drying, this material can be “recharged” with Al4C3 and reused to produce new counter-forms 1.
The different steps of a process for manufacturing blades or turbine rectifiers by densification according to a second embodiment of the present disclosure are presented in
The process according to the second embodiment differs from the process according to the first embodiment in that the step S110 of mixing the powders is broken down into two sub-steps. Indeed, while in the context of the first embodiment, the mixing step is carried out in a single operation, in which the composite material is formed in situ due to the presence in excess of the Al4C3 phase, step S110 of mixing the powders in the context of the second embodiment initially comprises mixing pure powders allowing to obtain the first phase (step S111), grinding this first phase into powder form, then mixing the first phase thus obtained with an Al4C3 powder allowing to obtain the composite material ex situ (step S112).
For example, during step S111, a first phase having formula TisAlC2 can be obtained by mixing pure powders of titanium, aluminum and titanium carbide (Ti:Al:TiC) according to the molar proportions 1:1.05:1.9 respectively. In this case, the titanium grains have a diameter of less than 45 μm, a purity of 99.5%. The aluminum grains have a diameter comprised between 45 and 150 μm, a purity of 99.5% and the titanium carbide grains have a diameter of 2 μm, a purity of 99.5%, and a density of 7.82 g/cm3. These different powders can be mixed in a ball mixer, then subjected to reactive sintering up to 1450° C. The porous mass thus obtained is crushed to be reduced to powder.
In this case, during step S600 in which the composite material shaken out by steaming is recovered so as to be reused for the manufacture of another counter-form 1, the material can be “recharged” with Al4C3 starting from step S112. It should also be noted that, during step S111, the pure powders can also be mixed with an Al4C3 powder. In this case, the Al4C3 powder contributes to the formation of the first phase, but is not in sufficient amount to form the composite material in situ, so that the second step S112 is necessary, and allows to add a necessary amount of Al4C3 powder, allowing to obtain the proportions of Al4C3 mentioned previously in the composite material.
The first and second embodiment above were described with reference to a first example of application, in which the process of solid densification of the powder contained in the counter-form 1, comprising steps S200 to S400, is made by SPS sintering. This example is however not limiting, other solid densification processes can be used.
For example, instead of SPS sintering, hot isostatic pressing (HIP) can be used. In this case, step S200 of filling the counter-form 1 with a powder constituting the blade to be manufactured, is also carried out then, in step S300, the counter-form 1 containing said powder is placed in a deformable container. HIP densification is carried out in step S400, in which a neutral gas (for example argon or nitrogen) is injected into the pressure enclosure, then applying uniform pressure in all directions on the container containing the counter-form 1. Once the densification is completed, and the container eliminated by mechanical or chemical machining, the counter-form 1 is then shaken out under the conditions described above in step S500, then the material is recovered in step S600.
Alternatively, instead of SPS sintering, an injection of a mixture of metal powder and a thermoplastic polymer (called MIM process for “Metal Injection Molding”) can be carried out. In this case, during step S200, the counter-form 1 is inserted into a MIM injection press and a powder constituting the material to be manufactured, mixed with a polymer binder, is injected into the counter-form 1. The polymer binder is then removed during a debinding process. Natural sintering without pressure on the part obtained can then be carried out. If the latter allows to sufficiently densify the part, in particular if the relative density is greater than 99%, the shakeout of the counter-form 1, in accordance with step S500, can be carried out. However, if it is necessary to further densify the part, natural sintering can be supplemented with an SPS or HIP densification cycle under pressure, repeating steps S300 and S400 described above. Alternatively, the debinding mentioned above can be immediately followed by SPS or HIP densification in accordance with steps S300 and S400, without going through natural sintering.
Thus, either one of the densification modes (SPS, HIP or MIM), or a combination thereof, can be used for the manufacture of the metal part, and apply to the two embodiments described previously and described with reference to
Although the present invention was described with reference to specific embodiments, it is obvious that modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, individual features of the different illustrated/mentioned embodiments can be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than a restrictive sense.
It is also obvious that all the characteristics described with reference to a process can be transposed, alone or in combination, to a device, and conversely, all the characteristics described with reference to a device can be transposed, alone or in combination, to a process.
| Number | Date | Country | Kind |
|---|---|---|---|
| FR2107728 | Jul 2021 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/FR2022/051385 | 7/8/2022 | WO |
