• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    A method of welding at least two pieces of green material, called green parts, by cofritting, comprising the following steps: - assembling the at least two green parts at a junction zone of these parts so as to form a set green monobloc, - debinding of the green monobloc assembly, and - sintering of the monobloc assembly so as to obtain a dense monobloc assembly forming a final part, characterized in that the two green parts (11, 12) each have a composition of different powder, so as to give a final piece (1) comprising at least two parts of different grain size.
    公开号:FR3066933A1
    申请号:FR1853418
    申请日:2018-04-18
    公开日:2018-12-07
    发明作者:Jean Richard Sebastien
    申请人:Safran SA；
    IPC主号:
    专利说明:

    IMPROVED MANUFACTURING METHOD OF A DUAL MICROSTRUCTURE PART
    TECHNICAL FIELD The present invention relates to the field of production of metallic or ceramic parts by a “shaping then debinding” process, for example a PIM (Powder Injection Molding) process, and in in particular, a co-sintering welding process.
    STATE OF THE ART [0002] In a conventional manner known per se, the production of parts by a "shaping then debinding" type process, in particular a PIM process, comprises four steps:
    - the development of a feedstock, or "green" material,
    - shaping (obtaining a "green" part),
    - debinding, and
    - sintering (obtaining a dense part).
    The formatting can for example be obtained by 3D printing or, in the specific case of the PIM process, by molding. The step of developing the feedstock (green material) mainly consists of mixing a powder of one or more metallic material (s) and / or ceramic (s) constituting the part to be manufactured with one ( or more) thermoplastic binder (s) based on polymers. This step is generally carried out using mixers and / or extruders under a high shear rate in order to ensure good homogeneity of the mixture. A relatively large amount of powder must be incorporated into the binder (s) to ensure the cohesion of the future part. If the mixture contains too much powder, this results in too high a viscosity which makes the molding step difficult and favors the appearance of cracks. If, on the contrary, the mixture contains too many binder (s), the risk of the workpiece collapsing during the debinding step increases.
    In the case of a PIM process, the molding step consists in placing the feedstock (conventionally in the form of granules) in an injection press similar to that of the plastic industry. In the case of other “shaping then debinding” type processes, this can in particular be 3D printing. We then obtain a part called the green part which is already substantially of the desired shape for the dense part (final).
    The debinding step consists in eliminating the thermoplastic binder (s) by a process adapted to its (their) nature (s). If this step is poorly controlled, it can be a source of damage to the part in production by the appearance of defects, for example cracks or chemical pollution. At the end of the debinding step, the part is porous.
    The sintering step consists of consolidating and densifying the unbound green part in order to obtain the final part. The part is thus heated, and this consolidation and densification is accompanied by a volume shrinkage which is a function of the initial composition of the feedstock. This step is carried out at a high temperature, but however such that the material of the unbound green part is not completely melted: under the effect of heat, the grains of material are welded together. A distinction is made between solid phase sintering (all the material of the part is in solid form) and liquid sintering (part of the material of the part has reached its melting point). At the end of the sintering step, a dense part is obtained, the final part.
    In addition and independently, the aeronautical industry has made, in recent years, many advances making it possible to increase the temperature capacity of the materials which constitute the parts of aircraft engines or helicopter turbines, by example. However, the temperature gains obtained remain limited and it is beginning to be recognized that a chemical composition and a microstructure of a given material cannot, by themselves, enable the objectives set by the specifications and technical needs to be fulfilled .
    Indeed, the performance of a part (made of a given material) lies in its ability to achieve, for an optimized homogeneous microstructure, the best compromise between the different mechanical properties required. These properties are often contradictory.
    One way of pushing the limits of current materials is to adapt the microstructure of the engine part to the local stresses on the environment of said part thereon.
    This amounts to producing, on the same part, a dual microstructure (of chemical composition or of grain size different from one part to another of the part) or gradient (of grain size or of chemical composition gradually varying along the room). For example, for a turbine disc, which is one of the most thermo-mechanically stressed parts in a turbojet engine, it is necessary to have a structure called "fine grains" in disc bore for its traction and fatigue characteristics. average temperature and a so-called "coarse grain" structure in the rim of the same disc in order to have better creep and cracking properties at high temperature.
    Currently, the best known means for producing a structural gradient (or dual) part is a heat treatment, as illustrated in document EP 3037194 A1, for example. This heat treatment may, however, lack precision as to the precise locations of the zones of the part whose microstructure must be modified compared to those where the microstructure must not be modified. In addition, in the event of an error, the entire part must be discarded, which can cause losses at high prices.
    Furthermore, the molding techniques (to create a final part with dual microstructure) used in PIM are very limited because the pressures involved during the injection step are such that it is practically impossible not to not break the green piece that you want to mold. More generally, it is difficult, regardless of the "shaping then debinding" process considered, to assemble large structural sub-assemblies once the different parts of the structural sub-assembly considered are finalized.
    One of the advantages of the PIM process (or any other process of the “shaping then debinding” type) is the possibility of co-frying different pieces, that is to say of assembling them upstream of the sintering step and thus carrying out, in parallel with the sintering, the welding of the different parts together. This allows, for example, to manufacture parts whose geometry would be too complex for direct shaping: we can thus decompose these parts too complex into sub-assemblies of easy-to-shape unit parts which are then welded together during the sintering step.
    Thus, the technical problem that the present invention seeks to solve is to produce engine parts meeting the needs of adapting their microstructures locally by means of a “shaping then debinding” type process, in particular the PIM process.
    STATEMENT OF THE INVENTION The invention proposes for this purpose a method of welding at least two pieces of green material, called green pieces, comprising the following steps:
    - assembly of at least two green parts at a junction zone of these parts so as to form a green monobloc assembly,
    - debinding of the green monobloc assembly, and
    - Sintering of the one-piece assembly so as to obtain a dense one-piece assembly forming the final piece, characterized in that the two green pieces each have a different powder composition so as to give a final piece comprising at least two size parts different grain. This process thus makes it possible to take advantage of the use of co-sintering of two green parts shaped from feedstocks of the same charge rate, containing powders of different particle sizes or chemistries, allowing after co-sintering to obtain a part unique to dual microstructure.
    It is recalled here that we speak of "particle size" to denote the size of the powder particles found in the feedstock and of "grain size" to denote an element characteristic of a microstructure. These two quantities have, a priori, no links between them.
    Another advantage of the claimed process is that the health of the assembly from the different parts to be welded together can be checked upstream of the debinding step (and therefore sintering). Thus, in the event of a scrap, the loss caused is less significant, in fact the assembly step is a step after which the added value of the part in production is low, unlike a green part already debonded or even already sintered. A defect detected after debinding or sintering leads to discarding a part with high added value, which is economically damaging.
    The welding process according to the invention may include one or more of the characteristics or steps below, taken in isolation from each other or in combination with each other:
    - the at least two green parts have powder compositions with different particle sizes,
    - the at least two green parts comprise powders having a Dg 0 less than 16pm, 25pm or 45pm,
    - the at least two green parts have different chemical powder compositions.
    The invention also relates to a dense one-piece assembly forming the final part, comprising at least two parts assembled by the method described above, characterized in that the two green parts have a different powder composition, so that that the final part has at least two parts with a different grain size.
    The final part according to the invention may also include green parts which have a different powder chemical composition or a powder composition with different particle sizes.
    The sintered part can then follow a standard and homogeneous heat treatment, simple to implement, because the dual microstructure is already generated.
    DESCRIPTION OF THE FIGURES The invention will be better understood and other details, characteristics and advantages of the invention will appear more clearly on reading the following description given by way of non-limiting example and with reference to the accompanying drawings in which :
    - Figure 1 is a perspective view of a part having two parts whose microstructure must be differentiated,
    FIG. 2 a is a schematic perspective view of two green parts with different microstructures intended to be assembled by the method according to the invention,
    FIG. 2b is a schematic perspective view of a green monobloc assembly intended to form a part of the type of that of FIG. 1 according to the method according to the invention,
    - Figure 3 is a perspective view of the part of Figure 2b whose differentiated microstructure has been shown schematically, artificially magnified.
    DETAILED DESCRIPTION In the present application, the term "feedstock" or "green material" means a following mixture:
    - at least one metallic and / or ceramic material constituting a part to be manufactured, and one (or more) binder (s) thermoplastic (s) based on polymer (s).
    This mixture is conventionally in the form of granules.
    Furthermore, in the present application, the term "green part" means a part in the course of manufacture which has already been shaped but which has not yet been unbonded. This green part therefore has the general shape of the final dense part, but since it has not yet undergone the sintering step, it does not yet have its final dimensions. Indeed, the sintering step involves a phenomenon known as volume shrinkage, which is a phenomenon of dimensional contraction involving a reduction in the dimensions of the part. This volume shrinkage is a function of the initial composition of the feedstock and in particular the loading rate of said feedstock. In a formulation, a filler is an immiscible solid substance dispersed in a matrix by mechanical means. Thus, the loading rate corresponds to the volume of powder in the feedstock.
    As shown in Figure 1, a user wishes to produce a final part 1 comprising two parts (or parts 11, 12) of different microstructures.
    For example, the user wishes to have a final piece 1 having small grains on the surface (to delay a fatigue initiation for example), and in the rest of the piece larger grains (to have resistance in creep for example).
    The production technique according to the method presented here consists in shaping the first green part 11 using a feedstock comprising a large particle size of powder, and the second green part 12 using a feedstock with finer grain size (see Figure 2a). The two parts 11, 12 are produced by means of a PIM process (or any other process for shaping green pieces of the 3D printing type for example) stopping at the molding step (or shaping). ) presented above.
    The two green parts 10, 12 are therefore assembled, at a junction zone 14 of these green parts 10, 12 so as to form a green monobloc assembly 10. This assembly in the green state can in particular be made by adding a weld bead of green material, as explained in French patent application No. 1754877.
    The two parts 11, 12 forming the one-piece assembly 10 are then debonded and sintered (co-sintered), like a conventional part obtained by the PIM process (or any other process for shaping green parts) to obtain the final piece 1.
    During sintering, the part of the monobloc assembly 10 comprising powders of finer particle size, corresponding to the first green part 11, has finer grains, while the part of the final part 1 comprising powders of particle size upper, corresponding to the second green part 12, has larger grains (see Figure 3).
    The two green parts 11, 12 already having different particle sizes, the monoblock 10 sintered assembly can then follow a standard and homogeneous heat treatment: in fact, the dual micro structure is carried out in the sintering step.
    The same type of result can be obtained by varying the chemical composition of the powders of each of the green parts 11, 12 rather than their particle size, for example by using a nickel-based superalloy with a variable carbon content. In this type of superalloy, the carbon precipitates in the form of carbide and this precipitated carbon content more or less opposes the magnification of the grain during sintering.
    In particular, using a first feedstock (a first part 11) comprising a chemical powder No. 1 and a second feedstock (a second part 12) comprising a chemical powder No. 2. It can, for example, be a René 77® alloy with a high carbon content as a chemical powder No. 1 and a René 77® alloy with a low carbon content as a powder Chemistry # 2. Ch thus obtains a sintered monobloc assembly 10 having a dual structure, thanks to the fact that the carbon content has, on the René 77®, an influence on the magnification of the grain during sintering.
    Various examples of embodiments allow the production of final parts 10 having different particle sizes. For example with Inconel 718 ^ powders having a D go lower than 16pm, 25pm or 45pm. We can also consider a case in which the two powders having a different chemical composition by taking, for example, René 77® containing 660 ppm of carbon or 160 ppm of carbon. These measured D go values relate to the granulometry of the powders used in the feedstock constituting each part taken separately.
    The parameter D go , represents a point on the distribution curve of the sizes of particles making up a part. This particular point indicates how large are 90% of the particles of the total volume of the part considered. For example, if the D go is 844nm, then 90% of the particles of the part considered have a diameter equal to or less than 844nm and 10% therefore have a larger size. This measurement can in particular be obtained by laser diffraction. Conventionally, to characterize the particle size of a part, we measure Di 0 , D 50 and D go . Di 0 is always smaller than D 50 which is smaller than D go . The closer their values, the more homogeneous the size of the powder particles.
    The technical lock resides in the shaping from the green state, of a final part 1 using two different feedstocks (green parts 11, 12). Indeed, it is important that the two feedstocks have a similar charge rate (proportion of powders / binders), which guarantees identical or substantially identical volume shrinkage of each of the green parts 11, 12 during sintering.
    It is also necessary that the sintering areas of the green parts 11,12 are compatible with each other.
    It must also be ensured that the shaping of the green parts 11 and 12 allows a healthy interface 14 to be obtained at the junction between the two green parts 11, 12.
    An illustration of the complete process for producing parts 5 assembled in green as described in the present application is, for example, produced with parts made of Inconel 718 ^:
    - injection of the parts to be assembled, for example two separate parts 11, 12 one of which would be of particle size A and the other of particle size B;
    - assembly of parts 11, 12 by the process claimed in the present application;
    - possible resumption of machining in the junction zone 14 if necessary;
    - debinding according to a conventional protocol defined on Inconel 71EP;
    - sintering according to a conventional protocol defined on Inconel 71EP.
    权利要求:
    Claims (8)
    [1" id="c-fr-0001]
    1. A method of welding at least two pieces of green material (11, 12), called green pieces, comprising the following steps:
    - assembly of at least two green parts (11, 12) at a junction zone (14) of these parts so as to form a green monobloc assembly (10),
    - debinding of the green monobloc assembly (10), and
    - sintering of the monobloc assembly (10) so as to obtain a dense monobloc assembly forming the final part (1), characterized in that the two green parts (11, 12) each have a different powder composition, so as to give a final part (1) comprising at least two parts with different grain size.
    [2" id="c-fr-0002]
    2. Method according to the preceding claim, wherein at least two green parts (11, 12) have powder compositions with different particle sizes.
    [3" id="c-fr-0003]
    3. Method according to the preceding claim, wherein the green parts (11, 12) comprise powders having a D 90 less than 16pm, 25pm or 45pm.
    [4" id="c-fr-0004]
    4. Method according to any one of the preceding claims, in which at least two green parts (11, 12) have different powder chemical compositions.
    [5" id="c-fr-0005]
    5. dense monobloc assembly (10) forming final part (1), comprising at least two green parts (11, 12) assembled by the method according to any one of claims 1 to 4, characterized in that at least two green parts (11, 12) have a different composition, so that the final part (1) has at least two parts with a different grain size.
    [6" id="c-fr-0006]
    6. Assembly according to the preceding claim, wherein the at least two green parts (11, 12) have a powder composition with different particle size.
    [7" id="c-fr-0007]
    7. The assembly of claim 5 or 6, wherein the at least two green parts (11, 12) have a chemical composition of
    [8" id="c-fr-0008]
    10 different powder.
    类似技术:
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    同族专利:
    公开号 | 公开日
    FR3066933B1|2019-05-10|
    EP3630399A1|2020-04-08|
    CA3064803A1|2018-12-06|
    JP2020521875A|2020-07-27|
    BR112019024015A2|2020-06-09|
    US20200180083A1|2020-06-11|
    CN110678283A|2020-01-10|
    RU2019136277A|2021-07-09|
    FR3066936A1|2018-12-07|
    FR3066936B1|2019-11-01|
    RU2019136277A3|2021-10-14|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US3717442A|1971-05-17|1973-02-20|Johnson & Co Inc A|Brazing alloy composition|
    EP2233232A1|2009-03-20|2010-09-29|Pratt & Whitney Canada Corp.|Process for joining powder injection molded parts|
    EP3059033A1|2013-10-15|2016-08-24|IHI Corporation|Method for bonding metal powder injection molded bodies|WO2021023925A1|2019-08-06|2021-02-11|Safran Aircraft Engines|Method for manufacturing a metal part|DE4332971A1|1993-09-28|1995-03-30|Fischer Artur Werke Gmbh|Process for the production of interlocking parts|
    CN101618617B|2009-08-03|2012-10-03|李新桥|Metal/ceramic three-layer composite material and preparation method thereof|
    CN102009175B|2010-10-08|2013-08-21|李亚东|Manufacturing method of multilayer shell-core composite structural part|
    CN106541141B|2015-09-18|2019-03-12|东睦新材料集团股份有限公司|A kind of manufacturing method of P/M cam|DE102020107105A1|2020-03-16|2021-09-16|Rolls-Royce Deutschland Ltd & Co Kg|Method for producing a sintered hybrid component|
    法律状态:
    2018-12-07| PLSC| Publication of the preliminary search report|Effective date: 20181207 |
    2019-03-20| PLFP| Fee payment|Year of fee payment: 2 |
    2020-03-19| PLFP| Fee payment|Year of fee payment: 3 |
    2021-03-23| PLFP| Fee payment|Year of fee payment: 4 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1754877A|FR3066936B1|2017-06-01|2017-06-01|IMPROVED CO-CLEANING WELDING PROCESS|
    FR1754877|2017-06-01|EP18726846.1A| EP3630399A1|2017-06-01|2018-06-01|Method for improved manufacturing of a dual microstructure part|
    JP2019562587A| JP2020521875A|2017-06-01|2018-06-01|Method for improved fabrication of dual microstructured parts|
    BR112019024015A| BR112019024015A2|2017-06-01|2018-06-01|improved manufacturing method of a double microstructure part|
    CN201880035115.0A| CN110678283A|2017-06-01|2018-06-01|Method for improving the manufacture of a dual microstructure component|
    US16/617,771| US20200180083A1|2017-06-01|2018-06-01|Method for improved manufacturing of a dual microstructure part|
    RU2019136277A| RU2019136277A3|2017-06-01|2018-06-01|
    CA3064803A| CA3064803A1|2017-06-01|2018-06-01|Procede de fabrication ameliore d'une piece a microstructure duale|
    PCT/EP2018/064535| WO2018220213A1|2017-06-01|2018-06-01|Method for improved manufacturing of a dual microstructure part|
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