CH716026B1 - Additive manufacturing process by laser beam of a mechanical part with a technical and / or decorative function and a mechanical part with a technical and / or decorative function. - Google Patents

Abstract

The invention relates to a method of additive manufacturing by laser of a mechanical part with a technical and / or decorative function, this method comprising the steps of: providing a laser beam (16) whose operation will be controlled by means of a computer into which is introduced a CAD computer file which is cut into one or more layers which, once superimposed, make it possible to form the structure of the desired mechanical part; provide a substrate (6) made of a ceramic material and place it in a manufacturing chamber (2) in which an atmosphere of a neutral gas is created; depositing on the substrate (6) at least a first layer of a powder of a first metallic material to be fused; leveling the first layer of the first metallic material to be fused; subjecting by means of the laser beam (16) the first layer of the first metallic material to a step of selective melting in accordance with the computer CAD file; where appropriate, depositing on the substrate (6) a second layer of a powder of the first metallic material or else of a second metallic material which is different from the first metallic material; leveling the second layer and subjecting this second layer to a selective melting step by means of the laser beam (16); if necessary, repeat the operations until obtaining the desired mechanical part; remove the mechanical part from the manufacturing chamber (2), remove the excess material and clean the assembly and, if necessary, subject the part to finishing operations such as polishing.

Description

Technical field of the invention

The present invention relates to an additive manufacturing process by laser beam of mechanical parts. The present invention also relates to such mechanical parts, in particular obtained by implementing the additive manufacturing process.

Technological background of the invention

[0002] The technique of additive manufacturing by laser fusion of metal parts has been known for more than two decades and is used in particular in the field of aircraft and automotive construction.

Briefly described, the selective melting process by means of a laser beam, also known by its Anglo-Saxon name Selective Laser Melting or SLM, is a rapid prototyping technique by melting a powder of a metallic material by means of a laser beam such as a CO2 carbon dioxide laser or a YAG laser, the maximum power of which is typically between 100 Watts and 2 to 3 kilowatts. This selective melting process is used to create, stratum after stratum, three-dimensional objects from powders of metallic materials which are brought to their melting temperature thanks to the energy supplied by the laser beam.

[0004] The conventional laser additive manufacturing process begins with the preparation of a computer file of the CAD (Computer Aided Design) type which will make it possible to define the volume of the part which is to be designed. This computer file includes one or more two-dimensional strata which, when superimposed, make it possible to reconstitute the part that one wishes to design.

After having spread a layer of uniform thickness of a metallic material in the powder state on a platform of an additive manufacturing machine by laser beam, the laser beam traces a first 2D layer on the surface of the metallic powder coating. Under the effect of the light energy provided by the laser beam, the metal powder melts, then solidifies in accordance with the outline of the first 2-dimensional stratum used to control the movement of the laser beam. A new layer of metal powder is spread over the entire surface of the platform, then the process of bringing the metal powder particles to their melting temperature by means of the laser beam is repeated until the part is finished.

[0006] The manufacture of the part by additive printing is done directly on the surface of the platform as described above. In some cases, this production begins with the production, layer after layer, of a support on the platform, and continues with the production of the part itself. The support is used in this case to mechanically support the part as it is being produced on the platform of the printing machine and allows the heat produced by the melting of the metal powder to be removed by means of the laser beam.

[0007] The part thus obtained must then be carefully removed from the platform of the additive manufacturing machine and cleaned of the unfused powder which surrounds it. If the part was manufactured with a support, the part is separated from the latter.

[0008] One of the drawbacks of conventional laser additive manufacturing processes lies in the fact that after completion of the desired part, this part must be detached from the platform of the additive manufacturing machine and then, if necessary, detached of its support. This is a delicate operation which takes a lot of time and during which, despite the precautions taken, many parts deform plastically and must be discarded.

Another technique of additive manufacturing by laser beam consists in providing a substrate that is installed in the machine before the start of manufacturing operations. This substrate on which the part will be manufactured comes flush with the surface of the platform of the additive manufacturing machine.

The substrate, which is metallic, makes it possible to effectively remove the heat caused by the melting of the powder and therefore to relax at least in part the thermal stresses which are present in the part during manufacture. An additional heat treatment after printing the part will completely eliminate thermal stresses. The metal powder by means of which the part is manufactured is most often of the same nature as the material from which the substrate is made because this promotes the attachment of the part to the substrate. Sometimes the composition of the alloy in which the powder is made varies slightly from the composition of the alloy of the substrate. It has also already been proposed to use to manufacture the part a powder made of a metal different from that in which the substrate is made, for cost reasons, for example when a precious metal is used to make the part, or good when using a different metal to machine such as titanium.

[0011] Therefore, until now, for the additive manufacturing of parts by means of a laser beam, the choice of material for the substrate and for the part manufactured by additive printing on the substrate was most often limited to the same metal for the substrate and the part. In some cases, it has been proposed to produce the part in a metal alloy slightly different from that in which the substrate is made or else in a material which has been shown to be compatible with the material of the substrate.

Summary of the invention

The object of the present invention is to provide an additive manufacturing process by laser making it possible to vary the choices of materials which can be used to produce mechanical parts in a reliable and reproducible manner.

[0013] To this end, the present invention relates to a method for additive manufacturing by laser of a mechanical part with a technical and / or decorative function, this mechanical part comprising a substrate and a structure formed on the substrate by additive manufacturing by laser, this process comprising the steps of: take a laser beam whose operation will be controlled by means of a computer into which is introduced a 2-dimensional CAD computer file which corresponds to the structure of the desired mechanical part, or else a CAD computer file to 3 dimensions which is cut into 2-dimensional layers which, once superimposed, make it possible to form the structure of the desired mechanical part, another computer file containing the operating parameters of the laser beam; provide a substrate made of a ceramic material whose melting temperature is higher than the temperature involved by additive manufacturing by laser; placing the substrate on a platform of a manufacturing enclosure; close the manufacturing enclosure and create in this manufacturing enclosure an atmosphere of a neutral gas; depositing on the substrate at least a first layer of a powder of at least a first metallic material to be fused; equalizing the first layer of the first metallic material to be fused so that this first layer has a substantially uniform thickness; activate the laser beam and subject by means of this laser beam the first layer of the first metallic material to a selective melting step in accordance with the CAD computer file which corresponds to the 2-dimensional layer of the structure of the desired mechanical part; depositing on the substrate at least a second layer of a metallic powder of the same material as that using which the first layer was produced or of a second metallic material which is different from the first metallic material; equalizing the second layer and subjecting this second layer to a step of selective fusion by means of the laser beam in accordance with the following two-dimensional layer of the computer CAD file; if necessary, repeat the operations until obtaining the desired mechanical part consisting of the substrate and the structure formed on the substrate by additive manufacturing by laser; remove the mechanical part from the manufacturing chamber, remove the excess metallic material and clean the assembly, and if necessary, subject the part to finishing operations such as polishing.

[0014] Thanks to these characteristics, the present invention provides an additive laser manufacturing process allowing the joint use of a solid ceramic substrate and a metal powder to produce mechanical parts with a technical and / or decorative function of very high quality. high quality. It has in fact been observed that the metallic structure obtained by laser fusion adheres sufficiently to the ceramic substrate on which this structure is manufactured and makes it possible to obtain mechanical parts which can be directly used in the objects in which the latter are intended to be mounted. This result is quite surprising given that a priori, the chemical affinity (ionic / covalent) between the metal atoms linked together by ionic bonds and the oxygen contained in ceramics whose atoms are linked by covalent bonds is weak. Nevertheless, it has in particular been observed that the titanium atoms associate well with the oxygen contained in the ceramic substrate to form molecules of titanium dioxide TiO2. Likewise, the aluminum atoms have a good affinity for the oxygen atoms of a substrate made of alumina, sapphire or zirconia, for example.

The substrate belongs to the mechanical part with a technical and / or decorative function which results from the method of the invention; this substrate is an integral part of this mechanical part, and is not intended to be separated from the structure obtained by additive laser manufacturing at the end of the process. In fact, it has been observed that this structure adheres sufficiently well to the surface of the substrate on which it has been produced so that the resulting mechanical part can be integrated as such into the object for which it is intended. Thus, thanks to the invention, the perilous step of separating the part obtained by additive laser manufacturing from the platform of the additive manufacturing machine is avoided, so that the risks of plastic deformation which can lead to the destruction of the piece, are avoided. Likewise, avoiding this separation step saves time, in particular because it is not necessary to have to fix, for example by gluing, the parts obtained by additive manufacturing on separate substrates.

[0016] According to special embodiments of the invention: before the step of selective melting of the layer of powder material, the substrate can be subjected to a surface treatment; the surface treatment consists of an ion implantation operation, a plasma torch treatment or a physical vapor deposition treatment; the substrate is preheated prior to the step of selective melting of the layer of powder material; the substrate is preheated to a temperature not exceeding 400 ° C; the thickness of the substrate is at least 100 µm; the neutral gas is argon and the volume concentration of oxygen in the manufacturing chamber is less than 0.5%; the ceramic material is chosen from the group formed by borosilicate glass, alumina, sapphire, titanium boride, titanium oxide TiO2, titanium carbide, tungsten carbide, silicon nitride, zirconia , emerald, ruby and diamond; the metallic material is chosen from the group formed by aluminum, steel, titanium, zirconium, palladium, platinum, silver and gold; the thickness of a layer of material deposited on the substrate is between 20 μm and 45 μm; the laser beam is of the Nd: YAG type; the maximum power of the laser beam is between 100 Watts and 300 Watts; the 2-dimensional layer of the desired mechanical part has an outline which delimits at least one surface. the size of the particles which form the powders is between 5 µm and 63 µm, and the powders of materials used are of the D10-D90 type, ie 90% of the particles which form these powders have a diameter less than 63 μm, and 10% of these particles have a diameter less than 5 μm.

[0017] The present invention also relates to a mechanical part with a technical and / or decorative function, this mechanical part comprising a ceramic substrate and a metal structure formed on the substrate by additive laser manufacturing.

[0018] It will be noted in particular that subjecting the ceramic substrate to a surface treatment by ion implantation, plasma torch or physical vapor deposition prior to the step of selective melting of the layer of powdered metallic material makes it possible to further improve again the bonding force of the structure formed on the substrate with the latter.

Brief description of the figures

Other characteristics and advantages of the present invention will emerge more clearly from the following detailed description of an example of implementation of the additive manufacturing process according to the invention, this example being given purely by way of illustration and not limiting only in conjunction with the appended drawing in which: FIG. 1 is a schematic representation of an additive manufacturing installation by laser beam which is suitable for implementing the method according to the invention; FIG. 2 is a detailed schematic view which illustrates the situation of the additive manufacturing installation before the start of the additive manufacturing process; FIG. 3 is a detailed schematic view which illustrates the deposition of the first layer of powdered material to be fused on the substrate; Figure 4 is a schematic detail view which illustrates the removal of excess powder material; FIG. 5 is a detailed schematic view which illustrates the step of selective melting by means of a laser beam of the first layer of powder material; Figure 6 is a schematic detail view which illustrates the step of selectively melting a layer of additional powder material; FIG. 7 is a detailed schematic view which illustrates the final step of cleaning the substrate, and FIG. 8 schematically illustrates a step of preparing the substrate by means of a plasma torch prior to the deposition of a first layer of powder material to be fused onto the substrate.

Detailed description of an embodiment of the invention

The present invention proceeds from the general inventive idea which consists in producing mechanical parts with a technical and / or decorative function in a single piece by means of an additive manufacturing process by laser beam. More specifically, the invention relates to an additive manufacturing process by laser beam in which the joint use of a solid ceramic substrate and a metal powder to produce the structure by laser additive manufacturing makes it possible to obtain mechanical parts with a function very high quality technical and / or decorative. It has in fact been observed that the metallic structure obtained by laser fusion adheres sufficiently to the ceramic substrate on which this structure is manufactured and makes it possible to obtain mechanical parts which can be directly used in the objects in which the latter are intended to be mounted. It seems that this is due in particular to the good chemical affinity (ionic / covalent) between the metal atoms and the oxygen contained in the ceramics. Thus, the titanium atoms combine well with the oxygen contained in the ceramic substrate to form TiO2 titanium dioxide molecules. Likewise, the aluminum atoms have a great affinity for the oxygen atoms of a substrate made of alumina, sapphire or zirconia, for example. The invention thus demonstrates that it is possible to combine or link together materials which, until now, were considered incompatible.

On the other hand, it was observed that we did not find the same affinity for the oxygen contained in the ceramic material in the case of gold. This is why, when it is desired to grow a gold structure by laser fusion on a ceramic substrate, it is preferable to subject the ceramic substrate to a surface treatment for example of the ion implantation, plasma torch or even physical deposition type. in the vapor phase. In the case of plasma treatment, the gas used to create the torch will preferably be compressed air containing 22% oxygen and approximately 70% nitrogen.

The ceramic substrate used to make the desired mechanical part is an integral part of this mechanical part and therefore does not need to be separated from the latter once the manufacturing process is complete. This ceramic substrate is therefore not intended to be sacrificed and will serve as a permanent support for the structure obtained by means of the additive laser manufacturing with which it forms the mechanical part according to the invention. The risks of deforming, or even destroying this structure, which were encountered in the prior art during the separation of such a structure from its manufacturing substrate, are thus avoided.

According to the method according to the invention, we begin by providing a substrate on which we will grow a structure by additive manufacturing by means of a laser beam. The shapes and dimensions of the substrate are chosen as a function of the subsequent use which will be made of the mechanical part resulting from the implementation of the present method. It will suffice for the substrate to have at least one flat surface on which the additive manufacturing operation can be carried out. For reasons of solidity, however, it will be preferred that the thickness of the substrate is not less than 100 μm. This substrate is made of a ceramic material, the melting point of which is higher than the temperature involved in additive manufacturing by laser melting. The substrate is made of a ceramic material such as alumina Al2O3, sapphire, titanium oxide TiO2 or else zirconia ZrO2. Other ceramic materials which are also suitable are silicon nitride Si3N4 and titanium carbide TiC.

Once the substrate has been selected and introduced into a manufacturing chamber, a layer of a material in the powder state is deposited on this substrate which will then be selectively fused by means of the laser beam. This pulverulent material is different from the material in which the substrate is made. This pulverulent material is a metallic material such as aluminum, gold, platinum, titanium, steel or even zirconium.

In the case of aluminum, the choice will preferably be made on an aluminum alloy 6061 comprising between 95.85 and 98.56% by weight of aluminum, 0.4 to 0.8% by weight of silicon, a maximum of 0.7% by weight of iron (no minimum required), 0.15 to 0.4% by weight of copper, a maximum of 0.15% by weight of manganese (no minimum required), between 0.8 and 1.2% of magnesium, between 0.04 and 0.35% of chromium, a maximum of 0.25% by weight of zinc (no minimum required), a maximum of 0.15% by weight of titanium (no minimum required), the concentration of the other elements not to exceed 0.05% by weight each, the total concentration of these other elements not to exceed 0.15% by weight. The 6061 aluminum powder used in the context of the present invention is formed from a mixture of particles whose diameter is between 5 and 63 μm.

Parts produced by depositing 10 to 20 layers of the aluminum powder detailed above were structured on a zirconia substrate. Likewise, a zirconia substrate has been used to fabricate parts from a titanium powder TiAl6V4.

In the case of gold, it is preferably 18 carat gold containing 750 thousandths of pure gold, 50 thousandths of silver and 198.5 thousandths of copper. The gold powder used in the context of the present invention is formed from a mixture of particles whose diameter is between 5 and 45 μm.

Parts made by depositing 10 to 20 layers of the gold powder detailed above were structured on sapphire and zirconia substrates.

Once the layer of powder material has been spread over the substrate, it is equalized by mechanical scanning in order to have a substantially uniform thickness, typically of the order of 15-50 μm. It will be understood that during this scanning operation, the powder particles whose diameter or at least one of the dimensions exceeds the thickness of the layer are removed from the substrate.

Once the layer of powder material is equalized, the manufacturing enclosure is closed and an atmosphere of neutral gas is created in the volume of this enclosure. The neutral gas chosen is preferably, but not limited to, argon, and the volume concentration of oxygen in the manufacturing chamber is less than 0.5%.

The laser device used in the context of the present invention is for example a Yb: YAG type laser, the maximum power of which is equal to 100 Watts and which emits continuously. By way of preferred but non-limiting example, depending on the type of laser beam chosen, the power thereof is set at a working value of between 10 and 35 Watts and its speed of movement on the surface of the substrate is between 100 and 700 mm / s. The laser beam melts the layer of powder material spread on the substrate in a pattern determined by a computer in which a computer CAD file is stored. This file corresponds to one or more 2-dimensional layers which, once superimposed, make it possible to form in the layer of powder material the structure of the desired mechanical part. Another computer file containing, for each stratum of the desired mechanical part, the operating parameters of the laser beam such as the power of the laser beam, the speed of movement of the laser beam and the path that this laser beam must travel is also used.

Each stratum of molten material therefore has a thickness between 15 μm and 50 μm. The thickness of the final structure can be of the order of 500 μm to 1 mm. The only difference between these values lies in the manufacturing time which is all the longer as the final structure is thick.

After having structured the first layer of powder material by fusing this material selectively in accordance with the instructions contained in the CAD computer file, the excess material is removed, then a second layer of a powder material which may be the same as that used to make the first layer or may be different. Finally, the operations are repeated until the desired mechanical part is obtained, consisting of the substrate and the structure formed on the substrate by additive manufacturing by laser. The resulting mechanical part is taken out of the manufacturing enclosure, the excess material is removed and the assembly is cleaned. The resulting mechanical part is ready for use.

FIG. 1 is a schematic representation of an additive manufacturing facility by laser beam which is suitable for implementing the method according to the invention. Designated as a whole by the general reference numeral 1, this additive manufacturing installation comprises a manufacturing enclosure 2 inside which is arranged a platform 4 on which is placed a substrate 6. Preferably, the platform 4 is coupled with a first piston 8 so that it can be moved vertically from bottom to top and from top to bottom. The additive manufacturing installation 1 also comprises a first reservoir 10 and a second reservoir 12 both arranged inside the manufacturing enclosure 2. The first reservoir 10 inside which a second piston 14 moves is used for storage of a powder material to be fused. As for the second reservoir 12, it serves as a receptacle for the excess powder of the material to be fused as well as for the waste resulting from the selective melting step. The manufacturing enclosure 2 also contains a laser beam 16 placed directly above the platform 4 on which the substrate 6 is placed, as well as a transfer head 18 for the powder of the material to be fused.

In Figure 2, the substrate 6 is flush with a printing surface 20 by actuating, if necessary, the first piston 8 which controls the movements of the platform 4 on which is placed the substrate 6. In the at the same time, the second piston 14 is actuated so as to bring a quantity of powder 22 of the material to be fused to the height of the printing surface 20.

In Figure 3, the transfer head 18 is responsible for bringing the amount of powder 22 of the material to be fused on the substrate 6. To this end, the transfer head 18 is equipped with a first and with a second squeegee 24 and 26 which can be selectively raised or lowered. As visible in Figure 3, to bring the amount of powder 22 on the substrate 6, the transfer head 18 is translated to the left of the figure, the first squeegee 24 being raised so as not to oppose the advancement of the quantity of powder 22, and the second scraper 26 being lowered in order to be able to move this quantity of powder 22.

Conversely, in Figure 4, the transfer head 18 is moved to the right of the figure with the first squeegee 24 lowered and the second squeegee 26 raised to level and compact the layer of powder material 28 which has been brought. on substrate 6.

In Figure 5, one proceeds to the melting of the layer of powder material 28 using the laser beam 16. For this purpose, the operation of the laser beam 16 will be controlled by means of a computer in which is introduced a CAD computer file which is cut into one or more layers which, once superimposed, make it possible to form the structure 30 of the desired mechanical part 32.

In Figure 6, the platform 4 on which is placed the substrate 6 is lowered by actuation of the first piston 8 to again bring the substrate 6 on the surface of which has been structured the first layer of powder material 28 flush with the printing surface 20. Then, if it is desired to structure a new layer of powder material on the surface of the substrate 6, the operations which have been detailed above are repeated in connection with FIGS. 2 to 5.

Finally, when the desired structure 30 is obtained by having subjected the first layer of powder material 28 to a selective melting step by means of the laser beam 16, it is possible, if necessary, to clean the mechanical part 32 formed. by the substrate 6 and the structure 30, for example by means of a vacuum cleaner 34 (see FIG. 7).

To improve the adhesion of the structure 30 obtained by additive manufacturing by means of the laser beam 16 on the substrate 6, it is possible, before the start of manufacturing operations, to subject the substrate 6 to a surface treatment at using a plasma torch 36 (see FIG. 8).

It goes without saying that the present invention is not limited to the embodiment which has just been described and that various modifications and simple variants can be envisaged by those skilled in the art without departing from the scope of the invention as defined by the appended claims. It will be understood in particular that within the meaning of the present invention and its particular embodiments, the term “mechanical part” is understood to mean parts which can be mechanically stressed like links of a watch strap, but also parts which do not 'have only a decorative function such as a dial for a timepiece on the surface of which a material structure has been fabricated.

Nomenclature

1. Installation of additive manufacturing by laser beam 2. Manufacturing enclosure 4. Platform 6. Substrate 8. First piston 10. First reservoir 12. Second reservoir 14. Second piston 16. Laser beam 18. Transfer head 20. Printing surface 22. Amount of powder 24. First squeegee 26. Second squeegee 28. Powder layer of material 30. Structure 32. Mechanical part 34. Vacuum cleaner 36. Plasma torch

Claims (18)

1. A method of additive manufacturing by laser of a mechanical part (32) with a technical and / or decorative function, this mechanical part (32) comprising a substrate (6) and a structure (30) formed on the substrate (6) by additive manufacturing by laser, this process comprising the steps of: - provide a laser beam (16) whose operation will be controlled by means of a computer into which is introduced a CAD computer file which is cut into one or more layers which, once superimposed, make it possible to form the structure of the desired mechanical part, another computer file containing the operating parameters of the laser beam; - Provide a substrate (6) made of a ceramic material whose melting temperature is higher than the temperature involved by additive manufacturing by laser; - Arranging the substrate (6) on a platform in a manufacturing enclosure (2); - Close the manufacturing enclosure (2) and create in this manufacturing enclosure (2) an atmosphere of a neutral gas; - depositing on the substrate (6) at least a first layer (28) of a powder of at least a first metallic material to be fused; - leveling the first layer (28) of the first metallic material to be fused so that this first layer (28) has a substantially uniform thickness; - activate the laser beam (16) and subject by means of this laser beam (16) the first layer of the first metallic material to a selective melting step in accordance with the CAD computer file which corresponds to the 2-dimensional stratum of the structure (30) of the desired mechanical part (32); - depositing on the substrate (6) at least a second layer of a powder of the same metallic material as that using which the first layer (28) was produced or else of a second metallic material which is different from the first metallic material; - leveling the second layer and subjecting this second layer to a step of selective fusion by means of the laser beam (16) in accordance with the following two-dimensional layer of the CAD computer file; - If necessary, repeat the operations until obtaining the desired mechanical part (32) consisting of the substrate (6) and the structure (30) formed on the substrate (6) by additive manufacturing by laser; - remove the mechanical part (32) from the manufacturing enclosure (2), remove the excess metallic material and clean the assembly, and - if necessary, subject the mechanical part (32) to finishing operations such as polishing. 2. Manufacturing process according to claim 1, characterized in that before the step of selective melting of the layer (28) of powder material, the substrate (6) is subjected to a surface treatment. 3. The manufacturing method according to claim 2, characterized in that the surface treatment consists of an ion implantation operation, a plasma treatment or a physical vapor deposition treatment. 4. Manufacturing process according to one of claims 1 to 3, characterized in that the substrate (6) is preheated prior to the step of selective melting of the layer (28) of powder material. 5. Manufacturing process according to claim 4, characterized in that the substrate (6) is preheated to a temperature not exceeding 400 ° C. 6. Manufacturing process according to one of claims 1 to 5, characterized in that the thickness of the substrate (6) is at least 100 microns. 7. Manufacturing process according to one of claims 1 to 6, characterized in that the neutral gas is argon and the volume concentration of oxygen in the manufacturing chamber is less than 0.5%. 8. Manufacturing process according to one of claims 1 to 7, characterized in that the ceramic material is chosen from the group formed by borosilicate glass, alumina, sapphire, titanium boride, titanium oxide. TiO2, titanium carbide, tungsten carbide, silicon nitride, zirconia, emerald, ruby and diamond. 9. Manufacturing process according to one of claims 1 to 8, characterized in that the metallic material is chosen from the group formed by aluminum, steel, platinum, gold, silver, palladium. , zirconium and titanium. 10. The manufacturing method according to claim 9, characterized in that the metallic material is a 6061 aluminum alloy, the particles of which have a diameter of between 5 and 63 microns. 11. The manufacturing method according to claim 9, characterized in that the metallic material is 18 carat 750 thousandths gold, the particles of which have a diameter of between 5 and 45 microns. 12. Manufacturing process according to one of claims 10 and 11, characterized in that the powders of materials used are of the D10-D90 type, that is to say that 90% of the particles which form these powders have a diameter. less than 63 µm, and 10% of these particles have a diameter of less than 5 µm. 13. The manufacturing method according to one of claims 1 to 12, characterized in that the thickness of a layer of material deposited on the substrate (6) is between 10 microns and 50 microns. 14. The manufacturing method according to claim 13, characterized in that the number of layers of material deposited on the substrate is between 10 and 20. 15. The manufacturing method according to one of claims 8 to 14, characterized in that the power of the laser beam is set at a working value of between 10 and 35 Watts and in that its speed of movement on the surface of the substrate (6) is between 100 and 700 mm / s. 16. The manufacturing method according to claim 15, characterized in that the laser beam (16) is of the Yb: YAG type. 17. The manufacturing method according to one of claims 8 to 16, characterized in that the 2-dimensional layers of the desired mechanical part (32) having an outline which defines at least one surface. 18. Mechanical part with a technical and / or decorative function, this mechanical part (32) comprising a substrate (6) made of a ceramic material and a structure (30) made of a metallic material and formed on the substrate (6) by manufacturing additive by laser.