FR3088016A1 - METHOD FOR MANUFACTURING A PART BY DENSIFICATION UNDER LOAD - Google Patents

Abstract

The invention relates to a method of manufacturing a part (2b) in a densification device under load which comprises the following steps: a) there is available: - a preform of the part to be manufactured which: i. comprises a core of a 1st powder material surrounded by a layer of solid and porous material or a layer of dense material, or ii. is completely made of a solid and porous material, and - of a fluid which is a second pulverulent material or a gas; b) the preform and the fluid are placed in the compression enclosure so that the preform is surrounded by the fluid; c) the contents of the compression enclosure are subjected to heating and at least one compression force is applied so as to obtain a part densified by sintering (2b).

Description

The field of the invention is that of the manufacture of parts, in particular mechanical parts, of complex shapes, by a densification technique under load of materials either partly powdery and partly solid and porous or dense, or completely solid and porous .

The invention thus relates to a method of manufacturing a part in a densification apparatus under load.

In the context of the present invention, the term "densification technique under load" means any sintering technique under load or creep aimed at consolidating a defined volume of metallic powders, ceramics, or organic materials (for example polymers) , by heating the latter and applying a uniaxial, multiaxial or isostatic pressure.

Many densification techniques under load of pulverulent or solid and porous materials are known and implemented daily in the industry. Among these techniques, we can cite:

forging, hot pressing (known under the English name "Hot Pressing"), hot isostatic pressing (known under the English name "Hot Isostatic Pressing"), assisted sintering in the field, also known as English acronym "FAST" for "Field Assisted Sintering Technology").

By "assisted sintering under field" means assisted sintering under electric field or magnetic field. Assisted sintering under an electric field is also known under the name of "flash sintering" and under the English acronyms "SPS" for "Spark Plasma Sintering" and "EGAS" for "Electric Current Assisted Sintering".

The SPS is known to subject a cylindrical volume of compressed powders to a pulsating current making it possible to significantly increase the kinetics of densification of these powders, and thus to obtain mechanical parts whose fine microstructures are preserved. However, the densification methods implemented by the SPS have the drawback of causing densification inhomogeneities in the case of parts of complex shapes having significant differences in thickness.

The production of parts of complex shapes by the conventional SPS process is therefore made difficult taking into account the complex geometry of the parts to be manufactured which results in differences in thickness and involves variations in shrinkage.

It should be noted that these densification heterogeneity problems relate exclusively to the sintering of parts of complex shape. Indeed, in the context of volumes to be densified in a simple form, that is to say having a constant thickness, the withdrawal distances are everywhere the same and thus make it possible to obtain a homogeneous densification of the part. There is therefore no reason to draw inspiration from documents relating to the sintering of non-complex shaped parts to solve the observed problems of densification heterogeneity.

There is thus a real need to overcome the heterogeneity of densification of complex parts manufactured by known techniques of densification under load.

The international application WO 2017/077028 A1 proposes a solution which attempts to overcome these difficulties of the heterogeneity of densification of complex parts manufactured by known techniques of densification under load. This solution consists in the implementation in a densification device under load in a compression direction of an assembly which comprises:

a volume to be densified of a pulverulent and / or porous composition and which, depending on the direction of compression, has variations in thickness, a counterform of pulverulent and / or porous composition, a deformable interfacial layer which is interposed between the volume to densify and counterform.

In this assembly, the geometric characteristics of the counterform will give the geometric shape to the complex part which is obtained from the volume to be densified.

During densification under load, the interfacial and deformable layer follows the withdrawal of the volume to be densified and, as a result, distributes the stresses transmitted by the counterform and the tool evenly over the volume being densified. The part thus obtained has a shrinking homothety over its entire surface in contact with the interfacial layer. In addition, the faults and fractures that can be generated within the counterform during the densification process are completely or partially blocked by the deformable interfacial layer and do not propagate in the volume being densified. The part thus obtained also has a preserved microstructure.

However, the assembly as described in international application WO 2017/077028 A1 has limits because the geometric shape of the densified part is dependent on the geometric characteristics of the counterform. However, certain very complex forms of the counter-form cannot, or even be difficult, to be implemented. The shape restrictions of the counterform thus generate shape restrictions of the part obtained with the assembly which is the subject of international application WO 2017/077028 A1. In other words, it is not possible to '' get all the pieces you want with very complex shapes.

This is why the inventors of the present invention have sought to overcome this drawback linked to the limitations of the complexity of the shape of the counterform of the assembly described in application WO 2017/077028 A1, by proposing a new manufacturing process. of parts in a densification apparatus under load which overcomes this counterform and thus makes it possible to obtain parts having any complexity of desired shape.

The subject of the invention is a method of manufacturing a part in a densification apparatus under load in at least one direction of compression which is equipped with a compression enclosure, said method comprises at least the following steps:

a) we have:

a preform of the workpiece which:

i. comprises a core made of a ^1st powder material surrounded by at least one layer of solid and porous material or at least one layer of dense material, or ii. is completely made of a porous solid material, and a fluid which is a ^2nd material powder or a gas;

b) the preform and the fluid are placed in the compression enclosure so that the preform is surrounded by the fluid;

c) the contents of the compression enclosure are subjected to heating and at least one compression force is applied in the at least one direction of compression so that:

the sintered preform in said at least one compression direction so as to obtain a part densified by sintering;

when the fluid is a ^2nd powder material:

- Said solid and porous or dense material and said 2 ^nd pulverulent material are chosen so that they do not react chemically with each other during this step c);

the 2 ^nd pulverulent material compacts or sintered, and if the 2 ^nd pulverulent material sintered, the hardness and the tenacity of this 2 ^nd pulverulent material at the end of step c) are less than that of the part densified sintering.

In the context of the present invention, the hardness of a material is determined by measuring the imprint that a penetrator leaves in this material under a given force. There are different methods of measuring hardness depending on the material considered (ie depending on whether it is a ceramic, an organic material such as a polymer or a metal). Examples of hardness measurements include Mohs hardness, Brinell hardness, Vickers hardness, Knoop hardness and Rockwell hardness.

Examples of standards for measuring the hardness of a material are for example the following standards: ASTM E 18-03 (Rockwell hardness), ASTM E 92-82 (Vickers hardness for metallic materials) and ASTM C1327: 2008 (Vickers hardness for ceramic materials). A person skilled in the art knows perfectly how to determine the hardness of a material according to the material considered.

In the context of the present invention, the term “toughness of a material” means the capacity of this material to resist the propagation of a crack. The tenacity of a material thus opposes its fragility. It can be measured by Charpy impact, bending and tensile tests on notched test pieces. Examples of standards for measuring the toughness of a material are for example the following standards: ASTM E 23-02a (Charpy method) and ASTM C1421: 2010 (toughness for ceramic materials). A person skilled in the art knows perfectly how to determine the toughness of a material.

The densification device under load can be a device chosen from forging, hot pressing, hot isostatic pressing and assisted sintering under field devices. These devices are perfectly known to a person skilled in the art, who therefore masters their operation.

The preform of the part to be manufactured may have been obtained using one of the techniques chosen from:

selective laser sintering (known by the acronym "SLS" for "Selective Laser Sintering"), selective laser fusion (known by the acronym "SLM" for "Selective Laser Melting"), modeling by deposition of wire, fusion by electron beam, stereolithography, additive manufacturing by jet of binders, and machining, taken alone or in combination thereof. These techniques are perfectly within the reach of those skilled in the art.

With the manufacturing process, the preform can have any shape, including a complex shape. By "complex shape" is meant that the preform has variations in thickness of continuous segments of its volume, within the framework of a projection in the direction of compression. It is advisable to distinguish the thickness of a form and its height, the latter being able to designate discontinuous segments of a volume, according to this same projection. For example, a volume in the form of a double cone of revolution, when considered along its axis of revolution, has a constant height but a variable thickness.

This is why the manufacturing method according to the invention has the advantage of being perfectly suited for the manufacture of parts, and more particularly of parts of complex shape.

The preform manufacturing techniques which have been listed above are suitable for obtaining such complex shapes.

In one embodiment of the invention, the preform comprises a core made of a ^1st pulverulent material which is surrounded by at least one layer of dense material.

In the context of the invention, the term "dense material" means a material which does not have porosity. Such a material is thus gas tight.

In this embodiment, the thickness of the layer of dense material can be between 10 μm and 1 mm, preferably between 200 μm and 500 μm.

The layer of dense material may have been obtained by sintering or laser fusion.

In embodiments of the invention, the preform comprises a solid and porous material which can:

either constitute an outer layer of the preform when the latter further comprises a core made of a ^1st powder material, or constitute the entire preform.

When the preform comprises a core made of a ^1st pulverulent material surrounded by a layer of a solid and porous material, the porosity of this solid and porous material can be closed or open. If the porosity is open, the pore size of this solid and porous material is preferably:

less than the grain size of the powder material ^1, forming the heart of the preform, and less than the size of the ^2nd powder material grains.

This prevents grains from ¹ powder material out of the layer of solid porous material with open porosity and that the grains of the ^2nd powder material entering said solid material and porous. In other words, this avoids the interpenetration of the grains of the 1 ^st and 2 ^nd pulverulent materials.

The material of the pulverulent core may be identical to or different from that of the layer of solid and porous or dense material.

The preform may include one or more layers of solid and porous or dense material. When the preform comprises several layers (for example superimposed on each other) of solid and porous or dense material, these different layers can be made of identical or different materials.

These materials are described below in the description of the materials of the preform.

The preform may include one or more layers of solid and porous and / or dense materials which may be the same or different from each other.

The materials of the preform and the ^2nd powder material are selected suitably so that they are not degraded during step c) of the manufacturing process.

The materials of the preform and / or the ^2nd powder material may be selected from metals, ceramics and organic materials.

The preform material and / or the ^2nd powder material may be at least one organic material which is synthetic or natural. For example, it may be lignocellulosic material, keratin or even a polymer.

The preform material and / or the ^2nd powder material may be an organic material which is at least one polymer which is selected from polymethyl methacrylate (PMMA), polyvinylchloride (PVC), polypropylene (PP), polyethylene terephthalate (PET), polystyrene (PS), polyamide (PA), polycarbonate (PC), polyetheretherketone (PEEK) and polyimide (PI).

The preform material and / or the ^2nd powder material may be at least one ceramic:

based on oxides, in particular chosen from zirconia, alumina, magnesia, zinc oxide, spinels, titanium oxides, barium or strontium titanates, silicas and silicates (for example cordierites and mullites);

non-oxidized, for example chosen from carbides, borides, nitrides and fluorides.

The preform material and / or the ^2nd powder material may be at least one metal. It can be a precious metal chosen by silver, gold and platinum, as well as their associated alloys. It can also be:

super alloys based on nickel or cobalt, nickel alloys, for example nickel alloys of Iconel 718 type, 316L stainless steel, FeNi, NiTi, titanium alloys, in particular the alloy TÎ-6AI-4V (commonly called hereinafter "titanium alloy TA6V"), aluminum alloys (for example 5086, 6061, 7075, MCrAI, FeCrAI, FeAI, TiAI, MgAI), or manganese alloys (for example MgSiSn, MgB?).

The materials of the preform and the ^2nd powder material may be the same or different.

The choices of materials constituting the preform and, where appropriate the 2 ^nd pulverulent material (that is to say in the embodiments of the invention in which the fluid is a 2 ^nd pulverulent material), are oriented by taking in consideration of the densification rules for these materials, in order to obtain, at the end of the method according to the invention, a part having a desired densification homogeneity.

These densification rules are based in particular on the fact that during densification under load in step c) of the method according to the invention:

if the material of the ^2nd powder material densifies faster than that of the preform, the material of the ^2nd powder material will stop the densification of the preform before it will present the densification desired sintering, which may result by density heterogeneities within the part obtained at the end of the process.

if the material constituting the preform densifies more rapidly than that of the ^2nd material powder, after step c) of the process according to the invention, the piece has the desired densification by sintering.

The rules for densification of materials are within the reach of those skilled in the art who will be able to choose the appropriate materials to obtain, at the end of the process, a part of the desired shape.

In one embodiment of the invention, the preform material and the ^2nd powder material have similar densification curves. This has the advantage of facilitating the prediction of withdrawals of material from the preform which are generated during step c) of the method according to the invention. To do this, it can be materials of the same type: metal / metal or ceramic / ceramic or organic material / organic material (for example polymer / polymer).

For example, the preform may be comprised of zirconia powder and the ^2nd powder material may consist of alumina powder. The coupling of these two materials finds its basis in their sintering behavior (temperature and densification curve) which is relatively similar. The zirconia powder of the preform densifies slightly faster than the alumina powder, and thus makes it possible to obtain a completely densified part by sintering during the process according to the invention.

In one embodiment of the invention, the materials of the preform and the ^2nd powder material are of identical chemical composition and microstructure. This has the advantage of facilitating the prediction of withdrawals of material from the preform which are generated during step c) of the method according to the invention.

In another embodiment of the invention, the preform material and the ^2nd powder material have a chemical composition and / or a different microstructure.

Implementation of material chemical composition and / or different microstructure broadens the possibilities of choice of materials of the preform and the ^2nd powder material. It is thus possible to implement, for the formation of the preform, a material with advanced and therefore costly technical properties, while selecting for the constitution of the ^2nd material powder, a lower cost material.

In one embodiment of the invention, the preform is made into a solid and porous material consisting of a titanium alloy TA6V and ^2nd powder material is alumina.

In embodiments of the invention, the fluid is a gas. It can be an inert gas, for example a gas chosen from argon, nitrogen and helium.

In the embodiments of the invention in which the fluid is a gas, the preform comprises a core made of a ^1st pulverulent material surrounded by at least one layer of dense material and the densification apparatus is an isostatic pressing apparatus hot.

In these embodiments, in step b) of the method according to the invention, the preform is placed in the compression enclosure of the hot isostatic pressing device which contains the gas. The preform is surrounded by the gas contained in the compression enclosure. Then, step c) of the method according to the invention is implemented by subjecting the compression enclosure to hot isostatic pressing.

These embodiments of the invention have the advantage over other conventional methods of densification under load using the hot isostatic pressing technique to dispense with a gas-tight sheath (generally made of metal) in which the powder of the material to be sintered is introduced. These embodiments of the invention are therefore less expensive and less restrictive for sintering a part compared to known methods of hot isostatic pressing. Indeed, the preform (ie the part which will sinter) has in its structure its "own" sheath and which consists of the layer of dense material which is gas tight.

In embodiments of the invention wherein the fluid is a ^2nd powder material, after step b) of the process according to the invention, the preform is surrounded by the ^2nd powder material. In other words, the preform is buried within the ^2nd pulverulent material into the compression chamber. In the context of the invention, the expression that "the preform is surrounded by the powder material 2 ^e" the entire surface or a part of the surface of the preform is in contact with the ^2nd powder material.

During step c), the temperature within the compression enclosure can be between 50 ° C and 2000 ° C, preferably between 800 ° C and 950 ° C. It will depend on the nature of the materials of the preform and, if necessary the ^2nd powder material. For example, when it is an organic material, the temperature within the compression enclosure is advantageously between 50 ° C and 500 ° C. In the case of ceramic, depending on its refractory nature, the temperature within the compression enclosure can reach up to 2000 ° C.

The temperature in the compression chamber is chosen suitably so that the material of the preform and, if necessary the ^2nd powder material do not degrade during step c). The choice of temperature within the compression enclosure is perfectly within the reach of those skilled in the art.

During step c), at least one compression force is applied which can be between 10 kN and 200 kN, preferably between 80 kN and 120 kN. The compressive force is appropriately selected such that the materials of the preform and, if necessary the ^2nd powder material do not degrade during step c). The choice of compression force is perfectly within the reach of those skilled in the art.

The direction of compression can be uniaxial, multiaxial or isostatic.

In the invention embodiments wherein the fluid is a ^2nd powder material, the temperature and compression force parameters are selected suitably such that:

the solid material and porous or dense of the preform and the ^2nd powder material does not chemically react with each other during this step c);

the 2 ^nd pulverulent material compacts or sintered, and if the 2 ^nd pulverulent material sintered, the hardness and the toughness of this 2 ^nd pulverulent material at the end of step c) are less than that of the part densified by sintering .

The adjustment of the temperature and compression force parameters is perfectly within the reach of the skilled person.

In the case of uniaxial compression, a preform and a ^2nd pulverulent material near the densification properties, stretching height (h) is related to the initial and final relative density of the component (d, , df) and at the desired final height (hf), by the following equation:

h, = hf. df / d.

This so-called “preform” equation makes it possible to better define the deformations of the deformable preform.

The withdrawal distances and the deformations induced on the volume of a given preform following the implementation of step c) of the method according to the invention can be predicted using simulation software, for example COMSOL multiphysics® simulation software developed by COMSOL.

The prediction of these data as to the withdrawal distances and the deformations of the preform are perfectly within the reach of those skilled in the art who can thus determine before the implementation of the method according to the invention, the characteristics of the preform (to know both its geometrical shape and the material (s) constituting it) and, where appropriate, the 2 ^nd pulverulent material, as well as the parameters of temperature and of the compression force to be applied as a function of the desired form of the part densified by sintering obtained with said process.

At the end of step c), the part is at least partly densified by sintering, preferably on its external part. In one embodiment of the invention, the part is completely densified by sintering.

The part obtained at the end of step c) preferably has a relative density greater than or equal to 95%, more preferably greater than or equal to 99%. By "relative density" is meant the density of the part obtained with the method according to the invention relative to the estimated density of this same part when it is dense. With the method according to the invention, it is sought that the parts obtained are as dense as possible, namely that they have a relative density which tends towards the value of 100%.

After step c) of the method according to the invention, the densified part is extracted from the compression enclosure by sintering. To do this, it may be necessary to fracture the 2 ^nd material which was pulverulent before stage c) of the process and which has compacted or which has sintered during this densification stage under load.

In one embodiment of the invention, the preform comprises at least one protuberance. This protuberance can help facilitate the extraction of the part densified by sintering obtained with the method according to the invention from the compression enclosure.

The part can be a part chosen from turbocharger turbines, turbine engine turbine blades, watch bodies, bearing balls and seals.

The invention will be better understood using the detailed description of an exemplary embodiment of a blade and a impeller obtained with the manufacturing process according to the invention.

DESCRIPTION OF THE FIGURES

Figure 1 is a photograph of the preform of a blade before performing step c) of the method according to the invention.

FIG. 2 is a photograph of the dawn at the end of the process according to the invention.

FIG. 3 is a photograph of the preform of a spinning wheel before carrying out step c) of the method according to the invention.

FIG. 4 is a photograph of the spinning wheel at the end of the process according to the invention.

EXPERIMENTAL PART :

I - Manufacture of a blade:

A vane 1b was produced according to the manufacturing method according to the invention in the following manner:

The material of the preform 1a was a powder of a TA6V titanium alloy which had the following size distribution:

- 10: 18 pm;

d50: 31.6 µm; d90: 43.5 pm.

A dawn preform 1a was obtained by the selective laser melting technique in an apparatus marketed by the company 3D SYSTEMS under the trade name ProX® DMP 200.

The parameters of this additive manufacturing were as follows:

scanning speed: 1800 mm / s;

laser power: 300 W;

the spacing: 85 µm;

the thickness of the powder bed: 60 μm.

The dawn preform 1a thus obtained at the end of the additive manufacturing had a pulverulent core which was surrounded by a dense layer with a thickness of 200 μm. The dimensions of the dawn preform la were as follows:

a height ha of 43.10 mm;

a width of 21.50 mm; a length La of 31.70 mm.

The preform 1a was then buried in alumina powder within the graphite compression enclosure of a densification apparatus by sintering assisted by electric field which is marketed by the company Sumitomo Coal Mining Co., Ltd under the trade name Dr. SINTER 2080.

The preform 1a was subjected to an assisted sintering cycle under an electric field along the direction of its width I. The cycle presented the following parameters: the initial temperature of the compression enclosure was 20 ° C. and it was increased for 18 minutes at 48.9 ° C / minute until waiting for the temperature of 900 ° C. The temperature was maintained for 10 minutes at 900 ° C;

the compression force applied was 6 kN during the first 14 minutes of the cycle, then it was increased for 4 minutes by 23.15 kN / minute until it reached 98.6 kN. The compressive force was maintained at 98.6 kN for 10 minutes.

During assisted sintering under an electric field, the preform sintered it so that:

its height increased from ha: 43.10 mm to hb: 43.60 mm; its width has decreased from: 21.50 mm to Ib: 14.85 mm; its length has decreased from La: 31.70 mm to Lb: 31.50 mm.

Thus, during assisted sintering under an electric field, only the width of the preform has varied. This was the direction in which the compressive force was applied. The variations in height and length of the preform detailed above are negligible.

There was thus obtained a blade 1b densified by sintering. More precisely, the blade 1b thus obtained was completely densified by sintering.

The densified dawn 1b was easily recovered by sintering because the alumina powder did not sinter during the assisted sintering cycle under electric field. Then, a light sanding made it possible to remove the alumina residues.

This blade 1b had perfect homogeneity in TA6V titanium alloy. Indeed, its relative density was greater than 99%. By "relative density" is meant the density of the part obtained with the method according to the invention relative to the estimated density of this same part when it is dense. In addition, the blade 1b had a homogeneous microstructure and a surface roughness on the order of 6 μm.

The photograph in FIG. 1 shows the preform 1a before step c) of the method according to the invention. The photograph in FIG. 2 shows the blade 1b obtained at the end of the manufacturing process according to the invention. There is a marked reduction in the width between the preform of the blade 1a and the blade 1b obtained at the end of the manufacturing process according to the invention.

It - Making a spinning wheel:

A spinning wheel 2b was manufactured according to the manufacturing method according to the invention in the following manner:

The material of the preform 2a was a powder of a TA6V titanium alloy which had the following size distribution:

- 10: 18 pm;

d50: 31.6 µm; d90: 43.5 pm.

A preform of the impeller 2a was obtained by the selective laser melting technique in an apparatus marketed by the company 3D SYSTEMS under the trade name ProX® DMP 200.

The parameters of this additive manufacturing were as follows:

scanning speed: 1800 mm / s;

laser power: 300 W;

the spacing: 85 µm;

the thickness of the powder bed: 60 μm.

The preform of the impeller 2a thus obtained at the end of the additive manufacturing had a pulverulent core which was surrounded by a dense layer with a thickness of 300 μm. The preform of the impeller 2a had a height of 44.3 mm and a diameter of 45.4 mm.

The preform 2a was then buried in alumina powder within the graphite compression enclosure of a densification apparatus by sintering assisted by electric field which is marketed by the company Sumitomo Coal Mining Co., Ltd under the trade name Dr. SINTER 2080.

The preform 2a was subjected to an assisted sintering cycle under an electric field in the direction of its height. The cycle presented the following parameters: the initial temperature of the compression chamber was 20 ° C and it was increased for 14 minutes by 48.5 ° C / minute until reaching the temperature of 700 ° C. Then, the temperature was increased for 8 minutes by 25 ° C / minute until reaching the temperature of 900 ° C, then maintained for 10 minutes at this temperature;

the compression force applied was 6 kN during the first 14 minutes of the cycle, then it was increased for 8 minutes by 5.38 kN / minute until it reached 49.1 kN. The compressive force was maintained at 49.1 kN for 10 minutes.

During assisted sintering under an electric field, the preform 2a sintered so that its height decreased from 44.3 mm to 35.5 mm. Its diameter increased slightly from 45.4 mm to 45.65 mm. A spinning wheel 2b was thus obtained densified by sintering. More specifically, the impeller 2b thus obtained was completely densified by sintering.

The densified impeller 2b was easily recovered by sintering because the alumina powder did not sinter during the assisted sintering cycle under electric field. Then, a light sanding made it possible to remove the alumina residues.

This impeller 2b exhibited perfect homogeneity in TA6V titanium alloy.

Indeed, its relative density was greater than 99%. In addition, the impeller 2b had a homogeneous microstructure and a surface roughness of the order of 6 μm.

The photograph in FIG. 3 shows the preform 2a before step c) of the method according to the invention. The photograph in FIG. 4 shows the impeller 2b obtained at the end of the manufacturing process according to the invention. There is a marked reduction in the height between the preform of the impeller 2a and the impeller 2b obtained at the end of the manufacturing process according to the invention.

Claims (12)

1. Method for manufacturing a part (1b, 2b) in a densification apparatus under load in at least one direction of compression which is equipped with a compression enclosure, characterized in that the method comprises at least the following steps : a) we have: a preform (la, 2a) of the workpiece which: i. comprises a core made of a ^1st powder material surrounded by at least one layer of solid and porous material or at least one layer of dense material, or ii. is completely made of a porous solid material, and a fluid which is a ^2nd material powder or a gas; b) the preform (la, 2a) and the fluid are placed in the compression enclosure so that the preform is surrounded by the fluid; c) the contents of the compression enclosure are subjected to heating and at least one compression force is applied in the at least one direction of compression so that: the preform (la, 2a) sintered in said at least one direction of compression so as to obtain a part densified by sintering; when the fluid is a ^2nd powder material: - Said solid and porous or dense material and said 2 ^nd pulverulent material are chosen so that they do not react chemically with each other during this step c); the 2 ^nd pulverulent material compacts or sintered, and if the 2 ^nd pulverulent material sintered, the hardness and the tenacity of this 2 ^nd pulverulent material at the end of step c) are less than that of the part densified sintering (lb, 2b). 2. Manufacturing method according to claim 1, characterized in that the preform (la, 2a) was obtained using one of the techniques chosen from selective laser sintering, selective laser fusion, deposition modeling of wire, electron beam fusion, stereolithography, additive manufacturing by jet of binders and machining. 3. The manufacturing method according to any one of claims 1 to 2, characterized in that the material of the preform (la, 2a) and / or the ^2nd powder material are selected from metals, ceramics and organic materials . 4. The manufacturing method according to claim 3, characterized in that the preform material (la, 2a) and / or the ^2nd pulverulent material is an organic material which is at least one polymer selected from poly-methyl methacrylate (PMMA), polyvinyl chloride (PVC), polypropylene (PP), polyethylene terephthalate (PET), polystyrene (PS), polyamide (PA), polycarbonate (PC), polyetheretherketone (PEEK) and polyimide (PI). 5. The manufacturing method according to claim 3, characterized in that the preform material (la, 2a) and / or the ^2nd powder material is at least one ceramic selected from zirconia, alumina, magnesia, the zinc oxide, spinels, titanium oxides, barium or strontium titanates, silicas, silicates, carbides, borides, nitrides and fluorides. 6. The manufacturing method according to claim 3, characterized in that the preform material (la, 2a) and / or the ^2nd powder material is at least one metal selected from silver, gold, platinum, nickel alloys, titanium alloys, aluminum alloys and manganese alloys. 7. The manufacturing method according to any one of claims 1 to 6, characterized in that during step c), the temperature within the compression enclosure is between 50 ° C and 2000 ° C. 8. Manufacturing method according to any one of claims 1 to 7, characterized in that during step c), at least one compression force between 10 kN and 200 kN is applied. 9. The manufacturing method according to any one of claims 1 to 8, characterized in that the compression direction is uniaxial, multiaxial or isostatic. 10. The manufacturing method according to any one of claims 1 to 9, characterized in that the fluid is a gas, the preform comprises a core made of a ^1st pulverulent material surrounded by at least one layer of dense material and the densification apparatus under load is an isostatic hot pressing apparatus. 11. The manufacturing method according to claim 10, characterized in that the gas is a gas chosen from argon, nitrogen and helium. 12. Part (lb, 2b) manufactured according to the manufacturing method according to any one of claims 1 to 11, characterized in that the part (lb, 2b) is a part chosen from turbocharger turbines, turbine blades of 10 turbojet engines, watch bodies, bearing balls and seals.