Method for producing a component

Abstract

In a method for producing a component (1) from at least two different materials (2, 4), a mould (2a) is produced from a first material (2), which is present in powder form, by means of selective laser melting. A second material (4) present in powder form is introduced into the mould (2a) formed from the first material. Pressure and heat are applied to the second material such that same forms a filling (4a) in the mould (2a).

Description

[0001] Process for manufacturing a component

[0002] This application claims priority from German patent application No. 10 2023 123 492.7, the contents of which are incorporated herein by reference.

[0003] The invention relates to a method for producing a component from at least two different materials. Furthermore, the invention relates to a method for producing a component from a powdered material with magnetic properties.

[0004] A wide variety of processes for manufacturing components from powdered materials are known from the state of the art. The process frequently used for this purpose is selective laser melting or laser powder bed fusion (LPBF), which is often colloquially referred to as 3D printing.

[0005] In order to produce components from two or more different materials, the known processes usually use two or more print heads or similar devices, which, however, represents a considerable amount of effort.

[0006] From EP 3 450 056 A1 a method for producing a component of a turbomachine is known, in which first a shell with an internal cavity corresponding to the outer contour of the component is produced from an intermetallic TiAl material and then a Ti alloy in powder form is filled into the cavity and the cavity is tightly sealed with the filled Ti alloy powder, wherein the tightly sealed shell with the enclosed Ti alloy powder is subsequently processed by hot isostatic pressing to form the component of the turbomachine.

[0007] DE 102010 046 579 A1 describes a component which is formed from a powder to be solidified by means of an energy radiation source, wherein the component has at least one cavity with a powder which is not solidified by the energy radiation source for forming a damping element.

[0008] DE 102016 204 905 A1 describes a method for producing a three-dimensional object by applying build-up material layer by layer and selectively solidifying it.

[0009] It is therefore an object of the present invention to provide a method for producing a component from at least two different materials, which can be carried out using simple means and with which high-quality components can be produced.

[0010] According to the invention, this object is achieved by the features stated in claim 1. In the method according to the invention for producing a component, a mold is created from a first material, which is in powder form, by means of selective laser melting. During selective laser melting, the first material is melted and then solidifies to form the shape. A second material, also in powder form, is introduced into this mold formed by the first material, and pressure and heat are applied to it so that it forms a filling within the mold formed by the first material. In other words, the second material is introduced into the mold formed by the first material by means of sintering and is thus bonded to the first material.

[0011] The method according to the invention can be carried out with comparatively little effort, particularly with regard to the use of machines, apparatus, and the like. In particular, only one device is required to carry out selective laser melting, rather than at least two or more such devices, as is the case with prior art methods.

[0012] The component produced using the method according to the invention is of very high quality, particularly in the transition area between the two materials, since the application of pressure and heat causes the second material, in powder form, to occupy the entire cavity created by the first material. However, the shape produced from the first material remains unchanged. The method according to the invention therefore allows for the production of very high-quality and, in particular, highly customized components, since selective laser melting enables a very wide variety of producible shapes.

[0013] A very advantageous development of the invention can consist in the second material having at least one different property than the first material. This makes it possible to produce a component that has different properties in different areas. For example, the second material can have lower strength than the first material. This prevents damage to the shape formed from the first material when the second material is introduced and in particular when pressure is applied to it. Additionally or alternatively, the two materials can have very different properties, for example high or low electrical conductivity. Three-dimensional additive manufacturing also allows these properties to be designed to be direction-dependent and locally different.This makes it possible to achieve component properties that would not be possible using a single material alone.

[0014] The introduced second material can differ from the first material, particularly in its reflective properties for electromagnetic radiation. This allows optically different materials to be combined to create optical patterns on the component surface, which can be used as decorative elements or for component identification. The patterns can differ from one another on the individual surfaces of the component, for example, the front and back. Alternatively or additionally, materials with different corrosion resistance can be used. The formation of local electrochemical elements, i.e., small-area corrosion elements, can create surface etching effects that further influence the optical properties.

[0015] Alternatively or additionally, materials with different electrical conductivities can be used, allowing the creation of three-dimensional internal structures that could be used, for example, for local conductive heating.

[0016] In a further advantageous embodiment of the invention, it can be provided that the mold formed by the first material has a frame that forms a cavity for receiving the second material. In this case, a mold is formed from the first material by means of selective laser melting, which mold has a frame so that the second material can be introduced into the cavity formed by the frame. This ensures that the entire second material, present in powder form, remains in the mold and thus contributes to the formation of the component. In this case, the frame becomes a component of the component produced using the method according to the invention.

[0017] Alternatively, it can be provided that an additional frame is arranged on the mold formed by the first material, which forms a cavity for receiving the second material. This allows greater freedom in the design of the mold formed from the first material. The additional frame, which can, for example, be part of a pressing tool used in the method for producing the component and in this case does not become part of the component produced using the method according to the invention, limits the expansion of the second material and absorbs the force acting on the second material due to the pressure exerted on it.

[0018] Particularly high-quality components are produced when both materials are metals.

[0019] A further improvement in the quality of the components produced by the method according to the invention results if at least one surface thereof is ground and / or polished.

[0020] An alternative solution to the problem is given in claim 10.

[0021] In this process, a first portion of a powdered material with magnetic properties is processed into a solid component using selective laser melting. A second portion of the powdered material is not processed using selective laser melting and remains in powder form. The portion of the powdered material processed into the solid component using selective laser melting forms a shell for the material not processed using selective laser melting, which remains in powder form. This process takes advantage of the phenomenon that certain materials are magnetic in powder form, but lose these magnetic properties when processed using selective laser melting.As a result, the second part of the powdered material, which is not processed by selective laser melting and remains in powder form, retains its magnetic properties and is, according to the invention, encased by the material processed into the solid component by selective laser melting.

[0022] Such a component produced by the method according to the invention, which has a magnetic region enclosed in a non-magnetic region, can be used for a wide variety of applications.

[0023] A very advantageous refinement of this process can involve aligning the remaining powdered portion in a magnetic field and filling any cavities present in the remaining powdered portion with a polymer or glass. This allows a specific magnetic property to be fixed in the second portion of the magnetic material remaining in powdered form. The magnetic properties of the powder used differ from conventional powdered materials in particular in that the individual powder particles are preferably single crystals, allowing the magnetic effect to be utilized particularly effectively.

[0024] Furthermore, it can be provided that the powdered material is an alloy that passes through a multi-phase region upon solidification. For example, the powdered material can be a stainless steel with the designation 1.4401, 1.4404 or 1.4435, which is usually completely or partially austenitic. The inventors have surprisingly discovered that when this material is converted from solid to powder form, which can be carried out using an atomization process, for example using the known ultrasonic plasma atomization process, the powdered material has magnetic properties and a ferritic structure. The atomization process should enable a sufficiently high cooling rate of the melt so that a ferritic structure is created. The rapid cooling stabilizes one phase and suppresses the formation of the second phase.It is even possible for each powder particle to form a single crystal with a ferritic structure. However, when this powder is converted from powder to solid form using selective laser melting, these magnetic properties and the ferritic structure are lost. The properties of a component made from the powder produced by the atomization process correspond to those of a component made from a conventional powder of the same alloy. However, the described process is also applicable to other alloys that undergo a multiphase region during solidification, for example, alloys based on titanium, nickel, or copper.

[0025] The alloys mentioned may also be intermetallic compounds, whose optical properties differ from conventional ones in that they exhibit unusual colors and / or, as a result of a phase transformation, a relief-like surface that leads to inhomogeneous light reflections. Unusual colors are considered to be colors that differ from the usual colors of metals, such as silver or gold. This effect is due to a defined atomic arrangement within the crystal structure of the intermetallic compounds.

[0026] In the following, embodiments of the invention are shown in principle with reference to the drawing.

[0027] It shows:

[0028] Fig. 1 shows a first step in carrying out a first method according to the invention;

[0029] Fig. 2 shows a second step in carrying out the method according to the invention;

[0030] Fig. 3 shows a component produced by the method of Figures 1 and 2;

[0031] Fig. 4 shows a first step in carrying out a second method according to the invention; and

[0032] Fig. 5 shows a component produced by the second method according to the invention.

[0033] Figures 1 to 3 show several steps of a method for producing a component 1 shown in its finished state in Fig. 3. The component 1 consists of at least two different materials, in the present case of exactly two different materials, both in powder form. Preferably, the two materials are metals or alloys, such as bronze and silver. Of course, other metals and alloys are also conceivable, such as two different gold alloys with different optical properties, a combination of gold and titanium alloys, a combination of gold and platinum alloys, a silver alloy with stainless steel, bronze with stainless steel, or a cobalt-chromium alloy with a silver alloy or stainless steel.

[0034] Fig. 1 illustrates a process step in which a mold 2a is created from a first material 2 by means of selective laser melting. A highly schematic device 3 is used for this purpose, of which only a laser head suitable for selective laser melting is shown in Fig. 1. Since the selective laser melting process is known per se, it will not be discussed in detail here.

[0035] In the process step shown in Fig. 2, a second material 4, also in powder form, is introduced into the mold made from the first material 2. In a further step, the second material is bonded to the first material 2 by applying pressure and heat and forms a filling 4a within the mold 2a formed from the first material 2. The pressure can be applied via a fixed stamp directly onto the powdered material 4, which is compacted by the pressure and heat via a sintering process and simultaneous mechanical deformation to such an extent that the density almost corresponds to the theoretical density of the second material 4. Deformation of the mold consisting of the first material 2 is prevented by inserting this same mold into an external, mechanically stable pressing tool.Since the structure and use of the pressing tool are known to those skilled in the art, it is not illustrated here. By pressing at elevated temperature, any pores that may still be present in the mold consisting of the first material 2 are simultaneously reduced. The pressure and heat are applied directly to the second material 4. For this purpose, the mold 2a is open in the direction from which the pressure is applied. The connection between the first material 2 and the second material 4 or between the mold 2a and the filling 4a is preferably such that all surfaces of the component 1 are completely sealed, which is achieved by the compaction of the second material 4 described above. The pressure can be applied on one side, two sides, or all sides at room temperature or elevated temperatures.The pressure can be applied to all sides, for example, using the known method of hot isostatic pressing. For all of the described pressure application options, the temperature should preferably correspond to 0.3–0.9, preferably 0.5–0.8, times the melting point of the material in Kelvin. The second material 4 located in the mold should be capable of being formed by time-dependent plastic deformation at elevated temperature to such an extent that even small pores can be closed. The pressure should be below the strength of the outer mold consisting of the first material 2. Subsequently, one or more surfaces of the component 1 can be ground and / or polished. In the present case, the second material 4 has a lower strength than the first material 2 at the forming temperature. Furthermore, the second material 4 preferably has a lower melting point than the first material 2.

[0036] The mold 2a formed from the first material 2 has a frame 5 which forms a cavity 6 for receiving the second material 4. In a manner not shown, an additional frame could also be arranged on the mold 2a formed from the first material 2, which could then form the cavity 6 for receiving the second material 4. This additional frame could be part of the pressing tool, not shown. The arrangement with the frame 5 results in a laterally closed mold 2a made from the first material 2, so that on surfaces that run parallel to the pressing direction, only the first material 2 is visible. In the arrangement with the additional frame, in contrast, on surfaces that run parallel to the pressing direction, only the second material 4 is visible. In both cases, the first material 2 and the second material 4 are only visible together on the sides or surfaces of the component 1 that are perpendicular to the pressing direction.This allows, on the one hand, to create visually appealing patterns, for example, for decorative applications. In this case, the two materials 2 and 4 are selected so that they differ in their optical properties, i.e., their reflective properties for electromagnetic radiation, and / or corrosion resistance. On the other hand, the closed frame 5, or the additional closed frame mentioned above, is also particularly suitable for use as a technical functional material. This allows differences in the electrical conductivity or magnetic properties of the two materials to be utilized particularly effectively.

[0037] Fig. 5 shows a further component 7 which is manufactured using a method described below. The material used for the component 7 is a powdered material 8 with magnetic properties. Preferably, the powdered material 8 is a stainless steel designated 1.4401, 1.4404, 1.4435, 1.4436 or 1.4571 or AISI 316 or AISI 316L. The powdered material 8 is preferably converted from its previously solid state into the powdered state by means of ultrasonic plasma atomization. It has been found that after ultrasonic plasma atomization of the aforementioned material from the solid form into the powder form, the previously non-magnetic material having an austenitic structure has magnetic properties and a ferritic structure in its powder form. Furthermore, the individual powder particles do not exhibit grain boundaries but consist of single crystals.In ultrasonic plasma atomization, the current intensity of the torch, the amplitude of the ultrasonic oscillation, and / or the strength of the shielding gas flow in the process chamber can be varied. This allows the size distribution of the powder particles to be influenced to achieve a particularly high yield of the desired size distribution. By changing the size distribution, the yield of single-crystal particles, which should preferably be smaller than 63 pm, can be increased.

[0038] A first portion 9 of the powdered material 8 is processed into a solid component by means of selective laser melting. For this purpose, the device 3 already described above can be used, as shown in Fig. 4. During this processing by means of selective laser melting, the above-described magnetic properties of the powdered material 8 are lost and they again correspond to those of a conventional AISI 316 or AISI316L steel. By varying the process parameters, the properties can be controlled so that some of the magnetic properties of the powder are retained. A second portion 10 of the powdered material 8 is not processed by means of selective laser melting and remains in powder form. By heat treatment, the magnetic properties of the powder can be changed so that they fully or partially correspond to those of AISI 316 or AISI316L steel.

[0039] As can be seen in Fig. 5, the part 9 of the powdered material 8 processed into the solid component by means of selective laser melting forms a casing for the second part 10 of the material 8 which is not processed by means of selective laser melting and remains in powder form. The second part 10 of the powdered material 8 can then be aligned in a magnetic field and any cavities present in the second part 10 of the powdered material 8 can be filled with a polymer or glass in order to fix the orientation of the loose, magnetic powder particles. The filler material can in particular be a solid metallic glass which can be filled into the cavities in a manner known per se, for example as a melt or by thermoplastic molding, and then solidifies in a manner likewise known per se. This material combination makes it possible to achieve particularly high electrical properties.Conversely, a magnetic composite material can be produced by mixing the metallic glass with the magnetic powder particles.

[0040] A further advantage resulting from the above-described magnetic or non-magnetic properties of the powdered material 8 is that, when magnetic and non-magnetic materials are used simultaneously, they can be separated from each other after a printing process using the known method of magnetic separation. Joint processing by selective laser melting of the previously magnetic powder, which is no longer magnetic after 3D printing, with another non-magnetic material (e.g., non-magnetic steels, nickel, copper, precious metal, titanium, cobalt, zinc, magnesium, or aluminum alloys) offers significant cost advantages when processing two different materials simultaneously, since the separation of both materials after 3D printing can be achieved in a virtually pure manner, which greatly improves the reuse of the powder.The pure magnetic separation of the magnetic powder made of AISI 316 or AISI 316L and the non-magnetic powder allows for better purity of the two different material areas in multi-material 3D printing, as the two powders are less mixed during reuse. This has a positive effect on the mechanical and corrosive properties of both materials. Such a separation process could be carried out independently of the process described with reference to Figures 4 and 5.

Claims

Patent claims 1. Method for producing a component (1) from at least two different materials (2, 4), wherein a mold (2a) is produced from a first material (2) in powder form by means of selective laser melting, wherein a second material (4) in powder form is introduced into the mold (2a) formed by the first material, and wherein pressure and heat are applied to the second material so that it forms a filling (4a) in the mold (2a).

2. Method according to claim 1, characterized in that the second material (4) has at least one different property than the first material (2).

3. Method according to claim 2, characterized in that the second material (4) differs from the first material (2) in its reflection properties for electromagnetic radiation.

4. Method according to claim 2 or 3, characterized in that the second material (4) differs from the first material (2) in its corrosion resistance.

5. Method according to claim 2, 3 or 4, characterized in that the second material (4) differs from the first material (2) in its electrical conductivity.

6. Method according to one of claims 1 to 5, characterized in that the mold (2a) formed by the first material (2) has a frame (5) which forms a cavity (6) for receiving the second material (4).

7. Method according to one of claims 1 to 5, characterized in that an additional frame is arranged on the mold (2a) formed by the first material (2), which frame forms a cavity (6) for receiving the second material (4).

8. Method according to one of claims 1 to 7, characterized in that the two materials (2,4) are metals.

9. Method according to one of claims 1 to 8, characterized in that at least one surface of the component (1) is ground and / or polished.

10. A method for producing a component (7) from a powdered material (8) with magnetic properties, wherein a first part (9) of the powdered material (8) is processed into a solid component by means of selective laser melting, wherein a second part (10) of the powdered material (8) is not processed by means of selective laser melting and remains in powder form, and wherein the part (9) of the powdered material (8) processed into the solid component by means of selective laser melting forms a casing for the part (10) not processed by means of selective laser melting and remaining in powder form.

11. Method according to claim 10, characterized in that the part (10) remaining in powder form is aligned in a magnetic field and cavities present in the part (10) remaining in powder form are filled with a polymer or glass.

12. Method according to claim 10 or 11, characterized in that the powdered material (8) is an alloy which passes through a multi-phase region during solidification.

13. Method according to claim 10, 11 or 12, characterized in that the powdery material (8) is produced by means of an atomization process.

14. Method according to one of claims 10 to 13, characterized in that the powdered material (8) is an intermetallic compound which has an unusual color and / or, as a result of a phase transformation, a relief-like surface leading to inhomogeneous light reflections.

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