EP3999264A1

EP3999264A1 - Process for manufacturing a part comprising aluminium

Info

Publication number: EP3999264A1
Application number: EP20737223.6A
Authority: EP
Inventors: Samuel Kenzari; Vincent Fournee
Original assignee: Centre National de la Recherche Scientifique CNRS
Current assignee: Centre National de la Recherche Scientifique CNRS
Priority date: 2019-07-18
Filing date: 2020-07-14
Publication date: 2022-05-25
Also published as: WO2021009183A1; FR3098741A1; FR3098741B1

Abstract

A process for manufacturing a part comprising aluminium is presented, which process comprises a step of selective laser sintering of a mixture comprising: a polymer powder for forming the matrix, a powder of a quasicrystalline aluminium alloy, and a powder of a first reinforcing compound forming a contact angle with a drop of polymer placed on the surface thereof of less than 90° and having a thermal conductivity at 20°C of less than 100 W/m.K. The mixture also comprises a powder of a second reinforcing compound, made of polymer, having a melting point (or decomposition temperature) higher than the melting point of the polymer of the matrix. The sum of the weight of the alloy and of the weight of the reinforcing compounds does not exceed 80% of the total weight of the mixture.

Description

Method of manufacturing a part comprising aluminum

Technical area

The present invention relates to a method of manufacturing functional parts comprising aluminum, in particular to a rapid method of manufacturing composite functional parts comprising aluminum. It also relates to the parts obtained using the process.

State of the art

It is known, in order to obtain rigid functional parts exhibiting a metallic appearance of cast aluminum, to subject a mixture of crystalline aluminum powders and a polyamide matrix to a selective laser sintering process, called SLS. Such parts are for example marketed under the name DuraForm ^® AF by the company BD SYSTEMS or under the name Alumide ^® by the EOS company.

Selective laser sintering, also called Selective Laser Sintering (SLS) in English, is a process allowing the shaping of a part by successive contributions of material in the form of powders.

This process uses a laser to transform a powdered material, comprising a mixture of metal powders and polymer powder, into a solid object by selective sintering without external pressure.

It is known that selective laser sintering makes it possible to produce parts without shape constraint, with great precision (± 0.2 mm), but with a high porosity rate.

When the mixture is sintered under the action of the laser, the parts have the drawback of having a high level of porosity, and therefore of not being sealed under pressure. It is thus necessary, if one wishes to obtain a satisfactory seal, to cover the material with a layer of waterproof coating, typically with a layer of resin, which makes the process for manufacturing the parts longer and more complex. To remedy these drawbacks, document FR 2 950 826 has proposed a process which comprises a step of selective laser sintering of a mixture comprising a polymer powder and a powder of a quasi-crystalline aluminum alloy. . When the process is implemented from a mixture of powders comprising a limited content of quasi-crystalline aluminum alloy, the part obtained has a very low rate of porosity, and therefore a higher seal than when the process is implemented from crystalline aluminum powder. By using a quasi-crystalline aluminum alloy, the part obtained exhibits improved mechanical properties, in particular wear, friction and hardness. An improvement of this patent is described in WO 2013/026972. It has been found that the addition of a reinforcing compound having given properties in terms of contact angle and thermal conductivity improves hardness and wear resistance, while exhibiting less brittleness and brittleness. while retaining the sealing properties of the parts obtained with the prior patent FR 2 950 826. The composite material manufactured according to this process is marketed under the name PAQc.

Object of the invention

The invention aims to further improve the mechanical properties of traditional PAQc materials.

General description of the invention The invention consists of an improvement of the method of WO 2013/026972, and proposes a method making it possible to rapidly obtain functional parts of complex shape having a metallic appearance and which have a very good seal, said parts further exhibiting reduced brittleness and very good hardness and wear resistance properties. The subject of the present invention is thus a method of manufacturing a part comprising aluminum.

The method according to the invention comprises a step of selective laser sintering of a mixture comprising: (a) a polymer powder to form the matrix,

(b) a powder of a quasi-crystalline aluminum alloy, and

(c) a powder of a first reinforcing compound forming a contact angle with a drop of polymer (matrix) placed on its surface of less than 90 ° and having a thermal conductivity at 20 ° C of less than 100 W / m.K, and

(d) a powder of a second reinforcing compound, polymer, having a melting temperature higher than the melting temperature of the polymer powder for the matrix (powder defined in (a)); the sum of the weight of the alloy and the weight of the reinforcing compound not exceeding 80% of the total weight of the mixture.

The present method is based on the method described in WO 2013/026972, and therefore allows the manufacture of functional parts resistant to friction and wear under severe conditions (humidity, sliding on metal or ceramic part). The parts are relatively light, of low density, and with isotropic properties.

In the present process, during the selective sintering of a layer or stratum of the powder mixture, laser energy is supplied to melt the polymer powder of the matrix. In accordance with feature (c), the first reinforcing compound is wetted by the molten matrix polymer at the specified angle.

One merit of the invention is to have found, surprisingly, a way to improve the mechanical properties of the conventional PAQc material, by adding the second reinforcing compound which is a polymer with a melting point (or degradation ) greater than that of the matrix, and this without compromising the other good characteristics obtained by the process, in particular the tribological and sealing properties. The product obtained with the present process has in particular a better tensile strength and / or an increased elongation at break. The first tests on products manufactured with the present process made it possible to observe a dimensional stability of the same level as that accepted industrially. The mechanical tests demonstrate a gain in elongation at break of 14 to 30%, and a gain in ultimate stress at break of 10 to 17% depending on the compositions, and that with good tribological and sealing properties.

The present process makes it possible in particular to manufacture parts which meet a porosity / tightness test corresponding to industrial demands and consisting in testing the porosity of a wall thickness of 1 mm in water at a temperature of 120 ° C and a pressure of 7 bars. To do this, a cylindrical sleeve is generally manufactured with a wall thickness of 1 mm, inside which the test fluid is applied (here water at 120 ° C. and 7 bars).

Obtaining such results is particularly satisfactory, given that for those skilled in the art the addition of a non-fusible filler to the matrix is conventionally considered to generate porosity.

The weight of the alloy is preferably less than or equal to 50% of the sum of the weight of the alloy and the weight of the reinforcing compounds.

The quantity of powder of the first reinforcing compound is chosen so that the volume fraction of the first reinforcing compound, after the sintering step, does not exceed 10% of the total volume of the part.

The quantity of powder of the second reinforcing compound is chosen so that the volume fraction of the second reinforcing compound, after the sintering step, does not exceed 10% of the total volume of the part. For this purpose, the weight of the second reinforcing reinforcing compound preferably does not exceed 10% of the total weight of the mixture.

According to the variants, thermoplastic or thermosetting polymers may be used for the second reinforcing compound. The powder of the second reinforcing compound may consist of a powder of a single polymer, or of a mixture of powders of different polymers (two or more). When it comes to a mixture, it is also possible to mix thermoplastic and thermosetting polymers. In all In these cases, the second reinforcing compound is formed from polymer (s) whose melting point is at least 1 ° C, preferably at least 5 ° C, above the melting temperature of the matrix. If the powder of the second reinforcing compound is a mixture of different polymers, then all of them meet this melting temperature criterion. The term “melting temperature” here refers to the temperature at which the polymer becomes liquid and can be shaped, as is conventionally understood for thermoplastic polymers. In the context of the invention, if the second reinforcing compound comprises a thermosetting polymer, then the term “melting temperature” is to be understood as the “degradation temperature”, which should therefore be situated above the temperature of. melting of the matrix polymer, in particular at least 1 or 5 ° C above.

The polymers which are particularly preferred for the second reinforcing compound are in particular the polyesters PA11 or PEEK.

Alternatively, is used as a second powder reinforcing compound marketed under the trademark Ekonol ^® by the company Saint-Gobain. It is a polyester powder with an average particle size of 60 to 75 mm; particles remain cohesive and solid at temperatures of 260-320 ° C, and above.

As is known, in the SLS process, the material is supplied layer by layer, therefore by strata, by scanning the laser so as to operate a selective sintering of the desired locations of the stratum. Care will be taken, especially when the difference between the melting temperatures is small, to control the energy delivered locally by the laser so as to melt only the polymer powder which constitutes the matrix, without melting the powder of the second compound.

The contact angle is less than 90 °, and preferably less than 40 °. The thermal conductivity at 20 ° C of the reinforcing compound is less than 100 W / m.K, and preferably less than 60 W / m.K.

The powder mixture may consist of matrix polymer powder, quasi-crystalline aluminum alloy powder, and powders of the two backing compounds. The mixture can also include adjuvants. It is possible for example to carry out a surface functionalization treatment of the particles of the first reinforcing compound with aminosilane in order to improve the adhesion between the polymer matrix and the alloy and / or the reinforcing compounds.

The first reinforcing compound can be chosen from ceramics and metal alloys; in general, the first reinforcing compound does not melt, respectively is not degraded by heat, within the framework of the SLS process implemented. In the case where the first reinforcing compound is a ceramic, the latter can be chosen from borides, carbides, oxides, nitrides and their mixtures.

In the case where the first reinforcing compound is a metal alloy, it can be chosen from stainless steels (iron-based), titanium alloys (titanium-based), bronzes (copper-based) , superalloys (in particular based on nickel, cobalt or iron) and their mixtures. The term "based on" means "comprising more than 50% by weight of".

The first reinforcing compound can be very particularly chosen from B ₄ C (Boron carbide), WC / Co (tungsten carbide / cobalt), TiB ₂ (titanium diboride), TiO ₂ (titanium dioxide), compounds with Al ₂ O _{3 based} (eg alumina, ruby, sapphire), SiO ₂ based compounds (eg silica, quartz, glass), ZrO ₂ (zirconia), BN (boron nitride), Si ₃ N ₄ (silicon nitride), stainless steels (e.g. Fe ₇₂ Cr ₁₈ Ni ₁₀ ; Fe ₇₀ Cr ₂₅ AI ₅ ), titanium / aluminum / vanadium alloys (e.g. TA6V type (like Ti ₉₀ AI ₆ V ₄ ) , copper-based alloys (for example Bronze Cu ₉₄ Sn ₆ or Cu ₈₉ Sn ₁₁ ; Cu ₅₅ Ni ₄₅ ), superalloys based on nickel, cobalt or iron, such as for example the alloys marketed under the name Inconel ^® by Special Metals Corporation The reinforcing compound can also be a mixture of these different compounds.

The part obtained by the method of the invention is a composite material comprising in particular a polymer matrix, an optionally multi-phase complex metal alloy, and two reinforcing compounds. The quasi-crystalline aluminum alloy can be a complex metal alloy comprising an atomic percentage of aluminum greater than 50%.

The process of the invention is implemented from a powder of a quasi-crystalline aluminum alloy. In the present text, “quasi-crystalline alloy” designates an alloy which comprises one or more quasi-crystalline phases which are either quasi-crystalline phases in the strict sense, or approximate phases. Quasicrystalline phases in the strict sense are phases exhibiting rotational symmetries normally incompatible with translational symmetry, that is to say rotational symmetries of order 5, 8, 10 or 12, these symmetries being revealed by diffraction techniques. By way of example, mention may be made of the icosahedral phase of point group m35 and the decagonal phase of point group 10 / mmm.

The approximating phases or approximating compounds are true crystals insofar as their crystallographic structure remains compatible with the translational symmetry, but which present, in the electron diffraction photograph, diffraction figures whose symmetry is close to a symmetry of order 5, 8, 10 or 12. These are phases characterized by an elementary cell containing several tens, even several hundreds of atoms, and whose local order presents arrangements of almost icosahedral or decagonal symmetry similar to the phases quasi-crystalline relatives.

Among these phases, mention may be made, by way of example, of the orthorhombic phase Oi, characteristic of an alloy having the atomic composition Al Cu ₂₀ Fe ₁₀ Cr ₅ , whose lattice parameters in nm are: a ₀ ⁽¹⁾ = 2.366 , b ₀ ⁽¹⁾ = 1.267, c ₀ ⁽¹⁾ = 3.252. This orthorhombic phase Oi is said to approximate the decagonal phase. The nature of the two phases can be identified by transmission electron microscopy.

Mention may also be made of the rhombohedral phase with parameters a _R = 3.208 nm, a = 36 °, present in alloys with an atomic composition close to Al ₆₄ Cu ₂₄ Fe ₁₂ . This phase is an approximate phase of the icosahedral phase.

Mention may also be made of orthorhombic phases 0 ₂ and 0 ₃ with respective parameters in nm a ₀ ⁽²⁾ = 3.83; b ₀ ⁽²⁾ = 0.41; c ₀ ⁽²⁾ = 5.26 as well as a ₀ ⁽³⁾ = 3.25; b ₀ ⁽³⁾ = 0.41; c ₀ ⁽³⁾ = 9.8, present in an alloy of atomic composition Al ₆₃ Cu ₁₇ Co _17.5 Si ₂ or else the orthorhombic phase O ₄ with parameters in nm a ₀ ⁽⁴⁾ = 1.46; b ₀ ⁽⁴⁾ = 1.23; c ₀ ⁽⁴⁾ = 1.24, which is formed in the alloy with atomic composition Al ₆₃ Cu ₈ Fe ₁₂ Cr ₁₇ .

Mention may also be made of a phase C, of cubic structure, very often observed in coexistence with the true approximate or quasi-crystalline phases. This phase, which is formed in certain Al-Cu-Fe and Al-Cu-Fe-Cr alloys, consists of an overstructure, by chemical effect of the alloying elements with respect to the aluminum sites, of a phase of Cs-CI type structure and lattice parameter ai = 0.297 nm. A diffraction diagram of this cubic phase has been published for a sample of pure cubic phase and atomic composition Al ₆₅ Cu ₂₀ Fe ₁₅ in number of atoms.

We can also cite an H phase of hexagonal structure which derives directly from the C phase as demonstrated by the epitaxy relations observed by electron microscopy between crystals of the C and H phases and the simple relations which connect the parameters of the crystal lattices, namely (to the nearest 4.5%) and

(to the nearest 2.5%). This phase is isotype of a hexagonal phase, noted

FAIMh, found in Al-Mn alloys containing 40% by weight of Mn.

The cubic phase, its superstructures and the phases which derive therefrom constitute a class of phases approximating the quasi-crystalline phases of similar compositions.

The quasi-crystalline alloys of the Al-Cu-Fe system and of the Al-Fe-Co-Cr system are particularly suitable for carrying out the process of the present invention. Mention may in particular be made of the alloys which have one of the following atomic compositions; Al ₆₂ Cu _25.5 Fe _12.5 , AI ₅₉ Cu _25.5 Fe _12.5 B ₃ , AI ₇₁ Cu _9.7 Fe _8.7 Cr _10.6 , and AI _71.3 Fe _8.1 Co _{12 , 8} Cr _7.8 . These alloys are marketed by the company Saint-Gobain. In particular, the alloy AI ₅₉ Cu _25.5 Fe _12.4 B ₃ is marketed under the name Cristome Fl, the alloy AI ₇₁ Cu _9.7 Fe _8.7 Cr _10.6 is marketed under the name Cristome A1 , and the alloy Al _71.3 Fe _8.1 Co _12.8 Cr _7.8 is marketed under the name Cristome BT1. These complex alloys have the advantage of having tribological (friction and wear), surface (low surface energy), mechanical (hardness, elastic limit and Young's modulus), thermal and electrical conductivity (high resistivity), different from those of crystalline aluminum alloys.

The polymer for the matrix can generally be chosen from thermoplastics. It may for example be chosen from thermoplastic organic polymers such as polyamides (for example of the Nylon 6, Nylon 11, Nylon 12 type), amide copolymers (for example nylon 6-12), polyacetates, polyethylenes. , as well as polyetheretherketone, designated by the acronym PEEK (PolyEtherEtherKetone in English).

The preferred polymers are polyamides and polyetheretherketone.

For better obtaining of the metallic appearance, the mixture may contain from 1 to 30% by weight of quasi-crystalline aluminum alloy, more particularly from 10 to 20%.

The volume fraction of the quasi-crystalline aluminum alloy can easily be calculated by a person skilled in the art from the mass and the density of the various constituents of the mixture.

The polymer powder added to form the matrix can represent from 20 to 95% by weight of the mixture, more particularly from 35 to 70%.

To obtain better mechanical properties, the mixture can contain from 1 to 50% by weight of reinforcing compounds, more particularly from 10 to 45%.

In the mixture of powders used for carrying out the process, the alloy particles, in particular of quasi-crystalline aluminum, preferably have an average particle size of between 1 and 120 mm, more particularly between 10 and 75 mm . The polymer particles for the matrix preferably have an average particle size of between 1 and 120 mm, particularly between 1 and 90 mm, and more particularly between 40 and 75 mm.

The particles of the first reinforcing compound and / or the second reinforcing compound preferably have an average particle size of between 1 and 120 mm, more particularly less than 90 mm, and even more particularly between 10 and 75 mm.

The particles of the powder of the second reinforcing compound are preferably generally spherical. Fiber-like forms should preferably be avoided. The powder particles can have a certain surface roughness, favorable to the bonding with the polymer of the matrix. The shape of the Ekonol ^® particles is considered advantageous in the context of the present process.

The contact angle can be measured by any technique known to those skilled in the art, and in particular by the so-called “drop-drop” method.

The drop drop method consists in placing a drop of liquid of about 0.4 mL on the surface of the material to be studied and in measuring the contact angle q between the liquid and the solid. This angle corresponds to the angle between the tangent to the drop at the point of contact and the surface of the material. In general, the shape of a drop on the surface of a solid is governed by three parameters: solid / liquid interfacial energy (g _sl ) solid / vapor interfacial energy (g _sv ) energy liquid / vapor interfacial (g _lv )

These three quantities are connected to the contact angle q by Young's law (fig. 1):

(g _sv ) = (g _sl ) + (g _lv ) ^▪ cos q

In this relation, the interfacial energies g _sv , g _sl and g _lv are expressed in mJ.m ^-2 and the contact angle in degrees.

By itself, the contact angle q gives an indication of the wettability of the material. Indeed, the measurement of q makes it possible to deduce the non-wetting (wide angle, low interfacial energy) or wetting (small angle, high interfacial energy) character of the surface. The lower this angle, the more the liquid will wet the surface. Conversely, complete non-wetting will be obtained with an angle of 180 ° (ie a sphere of liquid in contact with the substrate). The protocol used to prepare the surface of the samples before performing the contact angle measurements is described in FR 2 950 826, and is incorporated by reference.

The surface of samples A is water-polished with SiC abrasive paper up to grade 4000 (corresponding to an average grain size of less than 8 mm). Samples A are then cleaned in an ultrasonic tank then rinsed with methanol and dried with an electric dryer. Before and after each series of measurements, they are wiped with an optical paper and then left in the open air. To avoid polluting the A samples with the hands, they are handled using a metal clamp.

The measurements are carried out for example using an apparatus marketed under the name Digidrop Contact Angle Meter by the company GBX Scientific Instrument, and which is located in an air-conditioned room. This device is equipped with a light source B, a syringe C controlled manually to form the drop to be deposited, a sample holder whose movement (horizontal and vertical) is also done manually and a video camera D making it possible to obtain the image of the drop-syringe-sample assembly on a screen of a computer E. Before the measurements, a focus is made with the camera D at the place where a drop F will be filed. The angle q is measured in automatic mode via dynamic analysis of the image.

The present method can be implemented using conventional SLS equipment. In particular, the present method can be implemented using a device as illustrated in FIG. 3 of WO 2013/026972.

The selective laser sintering is preferably computer assisted. In a particular embodiment, the mixture of powders is heated to a temperature a few degrees Celsius lower than the melting temperature of the polymer added to form the matrix, for example to a temperature 1 to 10 ° C lower. at the melting temperature of the polymer. The energy required for fusion is then supplied by the laser. The energy of the laser is controlled so as not to exceed the melting temperature of the second reinforcing compound, respectively not degrade the second reinforcing compound when it is a thermosetting polymer.

A subject of the invention is also a part comprising aluminum obtained by a process described above. The parts obtained may have a volume porosity rate of less than 5%, and in particular less than 3%, and more particularly less than 1%.

Equivalently, the apparent density equal to the mass / volume ratio of the part may be greater than or equal to 95% of the theoretical density of the part, and in particular greater than or equal to 97% of the theoretical density of the part, and more particularly greater than or equal to 99% of the theoretical density of the part.

The process of the invention is particularly useful for the rapid manufacture of light parts with an apparent density of between 1 and 3 g / cm ³ and without shape constraint. Selective laser sintering allows easy and non-toxic production of parts that have the desired complex shape. The use of a quasi-crystalline aluminum alloy and of a reinforcing compound allows the production of parts having a seal that is superior to that of parts obtained with crystalline aluminum.

The parts obtained also exhibit remarkable mechanical properties, and in particular wear, friction and hardness properties which are better than those of parts obtained with crystalline aluminum.

According to another aspect, the invention relates to a composite part manufactured by selective laser sintering comprising a polymer matrix comprising: particles of a quasi-crystalline aluminum alloy, particles of a first reinforcing compound forming an angle of contact with a drop of polymer placed on its surface less than 90 ° and having a thermal conductivity at 20 ° C less than 100 W / m. K, wherein the matrix further comprises particles of a second polymeric reinforcing compound having a melting temperature higher than the melting temperature of the polymer of the matrix; and the sum of the weight of the alloy and the weight of the reinforcing compounds does not exceed 80% of the total weight of the composite.

According to the variants, the part comprises one or more of the following characteristics; the melting temperature of the second reinforcing compound is at least 1 ° C, preferably at least 5 ° C higher than the melting temperature of the matrix, the weight of the second reinforcing reinforcing compound does not exceed 10 % of the total weight of the composite.

the particles of the second reinforcing compound comprise particles of a thermoplastic polymer or particles of a thermosetting polymer, or a mixture thereof. In particular, the polymers of the second reinforcing compound can be chosen as described above.

the first reinforcing compound is chosen from ceramics, in particular borides, carbides, oxides, nitrides and their mixtures, and metal alloys, in particular as described above.

the quasi-crystalline aluminum alloy is a complex metal alloy comprising an atomic percentage of aluminum greater than 50%.

Detailed description of at least one embodiment of the invention

Other characteristics and advantages of the present invention will emerge more clearly on reading the following examples, to which it is however not limited, the description being given with reference to the appended drawings in which:

[Fig. 1] is a graph showing the stress-strain curves for four different compositions;

[Fig. 2] is a graph showing the evolution of the coefficient of friction as a function of the sliding distance for the four compositions of FIG. 1 (100C6 steel wiper, r _friction = 3 mm; F _N = 5 N, V _friction = 5 mm. S ^-1 ); and [Fig B] is a graph showing the evolution of the coefficient of friction as a function of the sliding distance for two other compositions within the framework of the present process.

Example 1 Tensile and friction tests were carried out with samples produced for four different compositions (which are detailed below): two compositions obtained with the process according to the invention, denoted compositions 1 and 2;

two compositions in conventional PAQc, denoted PAQc _G and PAQc _N. 3D tensile specimens were fabricated for these four compositions and were subjected to tensile tests with a constant strain rate of 1 mm. min ^-1 . The stress-strain curves in Fig. 1 demonstrate a significant improvement in the mechanical properties for composites 1 and 2 compared to the conventional PAQc samples. The modulus of elasticity (E), the strain at break (e _r ) and the stress at break (s _r ) measured for each of the compositions are reported in Table 1.

[Tables 1]

In general, the mechanical tests show that the gain in elongation at break varies from 14 to 30% and that the gain for the ultimate stress at break varies from 10 to 17%, for the compositions according to the invention. . Concerning the tribological properties of composites, pion / disc tests for composites 1 and 2 show a very low coefficient of friction (<0.25) and comparable to that of PAQc _G and PAQc _N.

Finally, cylindrical sleeves (wall thickness 1 mm) made with compositions 1 and 2 made it possible to verify the tightness of these materials by subjecting them to a test with water at 120 ° C and under a pressure of 7 bars. It has been observed that the compositions according to the invention do not alter the sealing property, while providing superior mechanical qualities.

Composition details:

Composite 1: 85% vol. Polyamide 12 + 10% vol. (QC alloy + Compound n ° 1) + 5% vol. Compound # 2 (polyester)

Composite 2: 85% vol. Polyamide 12 + 13% vol (Alloy Qc + Compound n ° 1) + 2% vol. Compound # 2 (polyester)

PAQC _G : 85% vol. Polyamide 12 + 15% vol. (Alloy Qc + Compound n ° 1)

PAQC _N : 85% vol. Polyamide 11 + 15% vol. (Alloy Qc + Compound n ° 1)

Example 2:

Other friction tests were carried out with parts manufactured according to the present process, the composition of which comprises a thermoplastic polymer for the second reinforcing compound.

As can be seen in Fig. 3, the tribological properties of composites 3 and 4 show a very low coefficient of friction (0.25) and comparable to that of other composites.

Composition details:

Composite 3: 85% vol. PA12 + 7.5% vol. (Alloy Qc + Compound n ° 1) + 7.5% vol. Compound No. 2 PA11

Composite 4: 85% vol. PA12 + 7.5% vol. (Alloy Qc + Compound n ° 1) + 7.5% vol. Compound # 2 PEEK

Claims

1. A method of manufacturing a part comprising aluminum, characterized in that it comprises a step of selective laser sintering of a mixture comprising: a polymer powder to form the matrix,

a powder of a quasi-crystalline aluminum alloy, and

a powder of a first reinforcing compound forming a contact angle with a drop of polymer placed on its surface less than 90 ° and having a thermal conductivity at 20 ° C less than 100 W / m.K,

characterized in that the mixture further comprises a powder of a second reinforcing compound, polymer, having a melting temperature higher than the melting temperature of the polymer of the matrix; and

in that the sum of the weight of the alloy and the weight of the reinforcing compounds does not exceed 80% of the total weight of the mixture.

2. Method according to claim 1, characterized in that the melting point of the second reinforcing compound is at least 1 ° C, preferably at least 5 ° C higher than the melting temperature of the matrix.

3. Method according to claim 1 or 2, characterized in that the second polymeric reinforcing compound is a thermosetting polymer, preferably a polyester.

4. Method according to claim 1 or 2, characterized in that the second polymeric reinforcing compound is a thermoplastic polymer, preferably a polyamide 11 or a PEEK.

5. Method according to claim 1 or 2, characterized in that the powder of

second reinforcing compound comprises powders of two or more different polymers, and preferably the powder of the second reinforcing compound comprises a powder of a thermoplastic polymer and a powder of a thermosetting polymer.

6. Method according to one of the preceding claims, characterized in that the second polymeric reinforcing compound is in the form of substantially spherical particles.

7. Method according to one of the preceding claims, characterized in that the weight of the second reinforcing reinforcing compound does not exceed 10% of the total weight of the mixture.

8. Method according to one of the preceding claims, characterized in that during the selective sintering of the powders in a stratum, the energy of the laser is controlled to melt the polymer powder to form the matrix without melting the powder of the second compound. reinforcement.

9. Method according to one of the preceding claims, characterized in that the

first reinforcing compound is chosen from ceramics, in particular borides, carbides, oxides, nitrides and their mixtures, and metal alloys.

10. The method of claim 9, characterized in that the first reinforcing compound is a metal alloy chosen from stainless steels, titanium alloys, bronzes, superalloys and mixtures thereof.

11. Composite part manufactured by selective laser sintering comprising a polymer matrix comprising:

particles of a quasi-crystalline aluminum alloy,

particles of a first reinforcing compound forming a contact angle with a drop of polymer placed on its surface less than 90 ° and having a thermal conductivity at 20 ° C less than 100 W / m.K,

characterized in that the matrix further comprises particles of a second reinforcing compound, in polymer, having a melting point higher than the melting temperature of the polymer of the matrix; and

in that the sum of the weight of the alloy and the weight of the reinforcing compounds does not exceed 80% of the total weight of the composite.

12. Part according to claim 11, wherein the melting temperature of

second reinforcing compound is at least 1 ° C, preferably at least 5 ° C above the melting temperature of the matrix.

13. Part according to claim 11 or 12, in which the weight of the second reinforcing reinforcing compound does not exceed 10% of the total weight of the composite.

14. Part according to any one of claims 11 to 13, wherein the particles of the second reinforcing compound comprise particles of a thermoplastic polymer or particles of a thermosetting polymer, or a mixture thereof.

15. Part according to any one of claims 11 to 14, characterized in that the first reinforcing compound is chosen from ceramics, in particular borides, carbides, oxides, nitrides and their mixtures, and metal alloys. .