WO2017037015A1 - Additive production of a shaped body - Google Patents

Abstract

The invention relates to a method for producing a shaped body. In the method, a plurality of material layers of the shaped body which lie one above the other are built up by means of an additive manufacturing process in a plurality of successive partial steps which are similar to one another, wherein in each partial step a powder is solidified to form a solid layer. The powder comprises a large number of particles, which each have at least one inner core and a shell substantially enclosing the core. The invention further relates to a powder for producing a shaped body by the method according to the invention. The powder comprises a large number of particles. The particles each have an inner core and a shell substantially enclosing the core. In this case the shells of the particles comprise material which melts below 1400 °C. The cores of the particles comprise at least one material which melts above 1700 °C. The invention further relates to shaped bodies produced by the method according to the invention.

Description

description

Additives producing a molded article The present invention relates to a method for the manufacture ^¬ development of a shaped body in which a plurality of superimposed layers of material of the shaped body by means of an additive manufacturing process in a plurality of successive and similar to each other substeps are constructed, wherein a powder solid in each partial step at a

Layer is solidified. Furthermore, the invention relates to a powder for such a production method and a molded article produced in this way. In known processes for the additive production of moldings, three-dimensionally shaped bodies are typically built up from a sequence of individually formed superimposed layers. These layers can be constructed, for example, each from a powdery or liquid starting material. In the case of pulverför ^¬-shaped starting material that can be prepared by various Ver ^¬ drive at the predefined locations at which the molding is to be constructed, are solidified. For the process ^¬ steps to solidify the powder in the respective

Layer can be used various methods in which, for example, a sintering at predefined locations by focused laser radiation or focused electron beams is achieved. Examples of such methods are selective laser sintering (SLS), selective laser beam melting (SLM for

"Selective laser melting"), laser metal deposition (LMD for "laser metal deposition", laser cladding, electron beam welding (EBW) and electron beam melting (EBM)).

A disadvantage of additive state-of-the-art production processes is that the material composition of the molded articles to be produced is often determined by the boundary conditions of the molded articles. set sintering processes is limited. The temperatures achieved during the sintering process in the powder are often between 850 ° C. and 1365 ° C. In such a case, the material of the powder used must, according to the prior art, be meltable at the set process temperature and secondly chemically stable. In particular, the powder must be stable against chemical decomposition even at the process temperature used. When carrying out the process in air, it must also be stable with respect to a chemical reaction with the air. With these constraints, the materials of the powder are typically limited to relatively low melting and chemically stable mate ^¬ rials. For applications in which moldings are required with high-melting and / or easily decomposable materials, the manufacturability with such additive manufacturing methods is usually severely limited.

There are numerous applications for which it would be worth wishing ^¬ to produce moldings with freely definable possible three-dimensional structures which are not limited in its material composition so. In particular, there are many applications in which moldings containing high-melting components such as refractory metals and / or refractory ceramics are required. An example of such an application are the contacts or contact carriers in medium and high-voltage switches. Here is the freest possible shape desirable by additive Her ^¬ position method is used to, for example, complex field controlling geometry. On the other hand, such contacts should, especially for use in vacuum or gas-insulated high-voltage switches, have refractory materials which at most melt or evaporate only slightly in the areas of arcs and flashovers.

The object of the invention is therefore to provide a production method which overcomes the disadvantages mentioned. In particular ^¬ sondere is to be made available a process with which moldings can be produced additively, which have a relatively high proportion of high-melting and / or easily decomposable materials. Another object is to provide a powder for such a production method and a molded article produced in this way.

These objects are achieved by the method described in claim 1, the powder described in claim 13 and the molded article described in claim 14.

In the inventive method for producing a shaped body a plurality of overlying material in which a powder is solidified into a solid layer at each sub-step ^¬ layers of the shaped body by means of an additive manufacturing ^¬ procedure in a plurality of successive and between themselves similar substeps constructed. In this case, the powder comprises a multiplicity of particles which each have at least one inner core and a shell substantially enclosing the core.

An essential advantage of the inventive method is that the material of the shell can be adapted to to satisfy the requirements ^¬ gene of the additive manufacturing process, while the material of the core thereof can be adapted to thereof Differing requirements for an application of the finished shaped body separately. Thus, for example, it is possible to use a powder having a relatively high proportion by weight of relatively high-melting material and / or easily decomposable material than would be possible in the case of an additive manufacturing method using a homogeneous powder made of a uniform material.

By a shell essentially enclosing the core, it should be understood here in general that such a shell covers the core over almost its entire outer surface. For example, such a degree of coverage for the multiplicity of particles can be on average above 60% of the surface area. surface of the core, lying in particular above 80%, particularly before ^¬ geous above 90% of the surface.

The powder according to the invention comprises a large number of particles and is suitable for the production of a shaped article with a method according to the invention. The particles each have an inner core and a shell substantially enclosing the core. The shells of the particles comprise a material which melts below 1400 ° C. The cores of the particles comprise at least one material wel ^¬ ches is not sintered at a process temperature of 1400 ° C as such, because it is at this temperature not meltable and / or decomposed and / or oxidized in air. A significant advantage of the powder according to the invention is that such a powder can be well processed by the comparatively easy fusibility of the shell with an additive manufacturing process in which the individual layers of the shaped body formed are solidified by powder sintering. The powder may be advantageous for this purpose ^¬ adhesive formed mainly of the described type of particles. The trays may be almost completeness, are ^¬ dig from a below 1400 ° C melting material ^¬ particular. Despite the choice of a non sinterable material at 1400 ° C for the cores thus a powder can be provided, which can be processed by means of an additive manufacturing process.

In particular, by the choice of a comparatively high melting point material for the cores can be achieved that the formed molded article is still relatively stable even at relatively high thermal, electrical and / or mechanical loads, in particular more stable than if it formed only from the material of the shells would have been.

The shaped body according to the invention is a shaped body which is produced by the method according to the invention. The use The additive manufacturing process can be recognized on the finished shaped body by the structuring in individually constructed material layers. For example, the layer boundaries of such a body built up in layers of sintered powder can generally be seen well at the deposited layer boundaries either with the naked eye or at least under the microscope. Also, the grain boundaries of the sintered powder can be recognized on such a molded article generally under the microscope at least for a part of the original particles, since the powder, in particular when it contains a core with a refractory material component, is generally not complete by such a sintering process is melted on ^¬ , but the particles are fused in these cases only in their outer regions with each other, and the original grain structure is at the centers with a high proportion of the material of the core at least in part still visible. Furthermore, in the case of the finished molded article according to the invention, the original structure of the powder particles used for the production process can also be clearly recognized, since there are islands of core material between the material of the shells which connects the original particles, which islands are at most incompletely fused within a sintered layer. Advantageous embodiments and further developments of the invention will become apparent from the dependent claims 1 and 14 claims and the following description. In this case, the described embodiments of the production method, of the powder and of the shaped body can generally be advantageously combined with one another.

Thus, the shells of the particles may have an average weight fraction of at least 10% of the average Vo ^¬ lumenanteils of the individual particles, in particular between 10% and 90% by volume. Particularly advantageously, the average volume fraction of the shells is even at least 10%, in particular at least 20% of the average total volume. By the aforementioned companies For the volume fraction of the shells, it can be achieved that the material of the shells significantly influences the processability of the particles with the additive manufacturing method. An upper limit for the average volume fraction of the shells may be at most 40%, for example at 60%, insbeson ^¬ particular. In such maximum Volu ^¬ menanteilen the mechanical and / or thermal properties of the molded article formed are significantly influenced by the material of the cores with affected.

The cores of the particles can at least one material aufwei ^¬ sen, which is not sintered as such at a process temperature of 1400 ° C as such. In particular, the cores can be made more uniformly ^¬ or even substantially from such Materi- al. It is thus achieved for these cores by the Ummante ^¬ ment with a shell in the first processability at the said process temperature. Without such a cladding processing of the cores would therefore with the above-mentioned methods of additive manufacturing not easily or only with increased process cost mög ^¬ lich.

The lack of sinterability of the non-jacketed Kernmateri ^¬ as may be due, for example, that the material of the cores at a process temperature of up to 1400 ° C, for example, a process temperature between 850 ° C and 1365 ° C in solid form, so not can be brought to melt or at least sufficiently melted. It may alternatively or additionally be based on the fact that the material of the cores chemically decomposes at such a temperature. Alternatively or additionally, a processing of air can be affected by the fact that the mate rial of the cores ^¬ without a shroud at said Prozesstemperator reacts with air. By a coating of the cores with a different material, a workability can be made with the respective additive Ferti ^¬ transmission method possible in these cases anyway. For example, a processing of graphite and / or carbon fibers and / or carbon nanotube-containing particles are made possible by such a sheath.

The cores of the particles may have at least one material melting above 1700 ° C. In particular, it may be a material from the group of Refraktärmetal- le, ceramics, glasses, carbon fibers, borides or carbides. Such materials are relatively high melting and therefore can be made processable by cladding with lower melting shells in an additive manufacturing process. It is achieved by the method of the present invention that a non-separating mixture of at least two physically possibly very different components can be produced and processed. For example, two or more material components of different density, different weight proportions or different volume fractions can be processed together without segregating during processing. With a powder with two separate powder components of different materials with optionally unterschied ^¬ union weights, sizes and / or shapes, however, segregation would easily occur.

The embodiments with a temperature above 1700 ° C Schmel ^¬ collapsing material component is is particularly advantageous for such At ^¬ applications in which the shaped body to high thermal and / or thermomechanical loads formed are exposed and, therefore, at least one should have high melting Materi ^¬ alkomponente. Advantageously, the cores of the particles may consist almost completely of one or more of the said refractory materials. Under a refractory metal is a metal in this context ver ^¬ were whose melting point is above that of platinum, in particular such a high-melting metal of the fourth, fifth or sixth subgroup. The metals Wolf ^¬ ram, chromium, molybdenum and titanium are particularly advantageous for use in a contact ^element . Nickel can also be advantageously used as a high-melting component of the shaped body. although, with its melting point, it is somewhat lower than the actual refractory metals. Among the borides prop ^¬ is net particularly TiB _second Among the carbides to be ^¬ Sonder tungsten carbide is suitable for body thermally particularly stable form.

The shells of the particles may comprise a material melting below 1400 ° C. In particular, the saddle ^¬ len of the particles may consist of such a relatively Low WC melting material a majority. Thus can be achieved that at least the shells of the particles can be bonded in one example ^¬ example triggered by laser radiation or an electron beam sintering process with each other without the cores have to melt it. The comparatively low-melting material of the cores may be, for example, a metal or a polymer, in particular it may advantageously be silver or copper. Advantageously, the shells of the particles may melt at a lower temperature than the cores. In this way, it can be achieved that the particles can be sintered during the additive layer construction without having to exceed a melting point or melting range of the material of the cores. In particular, the powder may then have a relatively high proportion of refractory material, so that the shaped body formed melts or vaporizes as little as possible during its operation. By choosing a comparatively high melting point material for the cores, it can be achieved that the shaped body formed is nevertheless comparatively stable even with relatively high thermal, electrical and / or mechanical loads, in particular more stable than if it were made only of the material of the shells would have been formed.

The additive manufacturing process may include a process step of laser beam welding, laser beam melting, laser beam sintering, laser metal deposition, laser cladding Recently, the electron beam welding and / or the electric ^¬ nenstrahlschmelzens. These processes are well be ^¬ Sonders to single out an inventive powder layers of the shaped body to verfesti ^¬ gene each with predefined geometrical rie by locally limited sintering of the powder.

The shells of the particles may each have at least two kon ^¬ center, the core substantially surrounding Teilscha- len. Such multiply coated particles have the advantage that certain physical properties such as thermal expansion coefficient, an absorption of the laser used, or electron beam or an elasticity ^¬ module of the shells can be tailored to the given requirements of the manufacturing process and / or the finished Formkör ^¬ pers can be adjusted. Furthermore, one of the partial shells, in particular the inner part shell, a Ma ^¬ TERIAL may have at least that improves the wettability of the cores with the material of the outer shell part. For example, nickel as a material for the inner shell improves the wettability of tungsten (as material for the core) with silver (as material for the outer shell).

The subshells can generally have different materials. It may also be advantageous if the materials of the subshells gradually merge into one another in the manner of a radial concentration gradient. As in, for example, an outer shell part may be substantially hen completeness, ^¬ dig out comparatively easily melting material consist, while an inner part shell comprises a mixture of a relatively higher melting point material of the core and low melting material of the outer shell. For example, the relative concentrations of the two components may vary gradually depending on the radius.

In general, the shell may have at least two material components, even in those cases where the shell is not clearly subdivided into two individual subshells. It can advantageously vary a concentration of the two material components as a function of a distance to the center of the respective particle. Even in such a case, such, for example, gradual variation may be advantageous in order to set desired physical properties in a targeted manner, as already described above in connection with the discrete partial shells.

The particles can each have a multiplicity of internal cores within a common shell. The cores may be advantageous in each case individual nanoparticles. A particular advantage with this embodiment is that nanoparticles can then be embedded in the molded body by the method, which without such a cladding could not readily be used in such an additive manufacturing process, since their high surface area leads to an excessive affinity for agglomeration exhibit. As a result, the flow properties of such a substantially nanoparticulate powder are very poor, and the processing of the powder is difficult. Possible environmental and / or health-damaging effects of the nanoparticles can also be reduced by embedding them in a common shell prior to their processing. The nanoparticles can, for example, carbon-containing nanoparticles, in particular particles of graphite, carbon fibers or Koh ^¬ lenstoffnanoröhren.

An average outer circumference of such nanoparticles may be, for example, between 10 nm and 250 nm.

The individual nanoparticles can produce a variety differed ^¬ Licher shapes and sizes. Since they are embedded together in a larger particle, such Variatio ^¬ NEN be compensated by the envelope and then no longer complicates the processing in the additive manufacturing process. For example, the nanoparticles may be approximately spherical particles, rod-shaped particles, disc-shaped particles, entirely asymmetric. see particles and / or act on a mixture of different such types of particles. For example, the overall particle formed by the co-coating may have an approximately spherical shape to facilitate processing in the additive manufacturing process.

The cores of the particles may advantageously be cured, be ^¬ are coated with the shell in front of them. This can be beneficial to increase the strength of the cores. For example, the cores can be pretreated by precipitation hardening. As a result, in particular, the strength of an alloy as a material for the core can be increased.

Generally, in the majority of the particles, the cores may have a substantially aspherical shape, and the shells may have a substantially spherical shape. A substantially spherical shape is to be understood as meaning a shape in which the surface of the particle does not deviate at any point with more than 20% of the radius from a sphere which encloses the particle. Under said

Radius should also be understood accordingly the radius of this einhül ^¬ lenden ball. Similarly, an aspherical shape is to be understood as meaning a shape in which the surface deviates from the enveloping sphere by more than 20% of the radius, at least in a partial region.

With such an embedding of an aspherical particle in a spherical outer shell, it can be achieved that the resulting powder can be processed much better in the additive manufacturing process than the cores not so coated. This is an additional effect, based on an approximation of the shape and added to the said advantages with respect to the different shell and core material communities.

Similarly, a relatively large distribution in the outer diameters of the cores can be achieved by embedding them in a shell with a smaller diameter distribution of the resultant balancing total particles. It can therefore be generally advantageous if an absolute Halbwertsbrei ^¬ te for the diameter distribution of the total particles in the powder is at most half as large as an absolute half-width of the diameter distribution of the embedded in these total particulate cores.

A mean circumference of the coated total particles can generally advantageously be between 5 μm and 100 μm, in particular between 20 μm and 40 μm. The thickness of the shell can advantageously be between 50 nm and 50 μm.

In general, the shell of the particles may have a mate rial ^¬ advantageous, which acts as a flux for a material of the core. Alternatively or additionally, in an embodiment with a plurality of partial shells, an outer partial shell may have a flux for a material of an inner partial shell. For example, phosphorus, silver, tin and zinc act as fluxes for copper, while copper, zinc and tin act as fluxes for silver.

The shaped body can have at least two material components for which there is a varying concentration gradient in at least one spatial direction in at least one part of the supporting element. In this way, the thermal and / or thermo-mechanical stability of the shaped body can advantageously be improved in ^comparison with a homogeneous composition. In particular, in the direction of a surface subjected to high thermal stress during use, a proportion of a component which melts at a higher level can be increased. Such a variation of the concentration may, for example, be gradual. However, it can also vary in discrete ranges between discrete concentration levels. The molded body may be an example of a supporting element of a switching contact of an electrical switch. Such a supporting element can either be the actual con ^¬ tact body of the switch contact or as a support body for serve the actual contact body, which is mechanically held by this. In any case, it is advantageous if such a bearing element of the switching contact at least ^¬ has a component of a high-melting material up because such switch contacts are exposed to high thermal loads during operation. In the column of a switching arc light ^¬ for example temperatures in the range between 5000 ° C and 10000 ° C may occur. At these temperatures, there is a melting of the surface of the switch contact. A melting of a larger volume fraction, however, should be prevented as possible, so that the switching contacts during

Closing such a switch does not irreversibly zusammenmel ^¬ merge. For this purpose, the load-bearing elements of such a switching contact should comprise a proportion of a refractory material.

Alternatively, the shaped body may be, for example, a turbine blade or an element of a turbine blade. Turbi ^¬ nenschaufeln, particularly gas turbine blades are exposed during operation high thermo-mechanical stresses and therefore have also advantageously has a relatively high proportion of high-melting material component. For example, the cores of the Pul ^¬ verpartikel used for such a component may comprise a superalloy or even essen- sentlichen be formed of a superalloy. Such a superalloy can be particularly advantageously a nickel-base superalloy.

Alternatively, the shaped article formed may be, for example, a filament or an electrode of a lamp. In particular, it may be a tungsten-containing electrode of a high-pressure gas discharge lamp. The tips of such electrodes are exposed during operation to high loads due to arc discharges and can therefore evaporate during operation. A complex shape of such components by an additive manufacturing method is advantageous when a high thermal resistance of the component can be achieved gleichzei ^¬ tig. The molded body formed by the manufacturing method described may generally advantageously have an internal cooling channel. Such a cooling channel can be used to cool the shaped body during a thermal load and, for example, to prevent melting. By the described additive manufacturing method, the at least one cooling channel can be easily manufactured. Insbeson ^¬ more complete and complex shapes can be produced, thus for example meandering structures and / or structures of several branched cooling channels. The integration of cooling channels is generally useful for the production of moldings for use in switch contacts, turbine blades, electrodes and / or filaments.

The shaped body can have at least two material components for which there is a concentration gradient in at least one spatial direction in at least one part of the shaped body. In this way the thermal and / or thermomechanical be advantageously improved stability of the shaped body compared to a homo ^¬ antigenic composition. ^¬ advantageous way, a proportion of a higher melting component can be increased in the direction of a thermally and / or mechanically heavily loaded in use of the molding surface. Within such a surface, a portion of a higher melting component may be increased, especially in the direction of a thermally and / or mechanically heavily loaded tip or edge of the molding. Such a variation of the concentration may, for example, be gradual. However, the concentration may also vary in discrete ranges between discrete concentration levels.

In the following, the invention will be described by means of some preferred embodiments with reference to the appended drawings, in which: FIG. 1 shows a schematic sectional view of a particle of a powder according to a first exemplary embodiment,

 FIG. 2 shows a schematic sectional view of a particle of a powder according to a second exemplary embodiment,

 FIG. 3 shows a schematic sectional view of a particle of a powder according to a third embodiment,

 FIG. 4 shows a schematic sectional view of a particle of a powder according to a fourth exemplary embodiment,

 Figure 5 is a schematic perspective view of a

 Shaped body according to a fifth embodiment shows

 Figure 6 is a schematic cross-sectional view of a

 Switching contact with two contact elements according to a sixth embodiment shows,

 FIG. 7 shows a schematic cross-sectional view of a turbine blade according to a seventh exemplary embodiment, and

 Figure 8 shows a schematic side view of a lamp filament according to an eighth embodiment.

1 shows a schematic sectional view of a particle of a powder 5 is shown according to a first Ausführungsbei ^¬ play of the invention. Shown is a substantially spherical particle 5 with an inner core 7 of the material A and an outer shell 9 of the material B. Here, material B has a lower melting point than material A, so that a powder of such particles 5 for producing individual sintered layers 3i can be used in an additive manufacturing process without the cores 7 of material A having to melt in this sintering process. For example, material A is carbon, tungsten, tungsten carbide, tin oxide and / or nickel may have Bezie ^¬ hung example be a majority of such material. The shell 9 may, for example, comprise silver and / or copper. Hung as the majority of such a material B ^¬ best hen. By additive sintering of such particles 5, a molded body 1 can be produced which, despite the relatively easy fusibility of the shell material B, can have a high thermal resistance overall.

2 shows a schematic sectional view of a particle of a powder 5 is shown according to a second Ausführungsbei ^¬ play of the invention. Shown again is a substantially spherical particle 5 with an internal one

Core 7 of the material A and an outer shell 9, where ^¬ in the case in this case, two partial shells 9a and 9b summarizes. The outer partial shell 9b may, for example, consist of a material M which melts more easily, and the inner shell may consist of a mixture of the materials A and B. As an alternative to the example shown here with discrete subshells, a concentration of the material A within the shell 9 or within a subshell 9a can continuously drop from the inside to the outside with the radius r, with a concentration of the more easily melting material B corresponding to the outside increases. Or, as described above, the inner shell may increase the wettability of the core with the outer shell material. 3 shows a similar sectional view of a Parti ^¬ kels 5 is shown according to a third embodiment of the invention. Shown is a plurality of cores 7i embedded in a common matrix 8. This matrix 8 already acts as the first envelope of the cores 7i. The matrix 8 is wrapped in the example shown of a further shell 9, wel ^¬ surface having a lower melting material at least in comparison to a material of the cores A B 7i. The material of the matrix 8 can in principle be higher, lower or equal to the same compared to the material B melting. It may speak for example, the material of the outer shell 9 ent ^¬ so that the matrix 8 and shell 9 may pass each other in ^¬ without an interface. But it can also be as in Figure 3 shown an interface and there may be ^¬ different materials for matrix and shell are used.

FIG. 4 shows a similar sectional view of a particle 5 according to a fourth exemplary embodiment of the invention. Shown is an aspherical core 7, the example ^¬ at a point pl has a distance rl to a center z of the core, which deviates by more than 20% from an enveloping ball 10a of the core. This aspheric core 7 is enveloped by a substantially spherical shell 9, the outer surface of which differs by no more than 20 ~ 6 from an enveloping sphere 10b of the shell 9 at any point. From the largest ^¬ deviation is given for the cross-section shown for example in the point p2, wherein the distance r2 from the center differs even only slightly from the radius of the enveloping ball 10b from ^¬.

FIG. 5 shows a schematic perspective illustration of a shaped body 1 according to a further exemplary embodiment of the invention. Shown is a cuboidal shaped body 1, which has a refractory and a lower melting Mate ^¬ rialkomponente, wherein the proportion of refractory ^¬ the component along the shown spatial direction x increases. The spatial direction x shown is also the direction in which the layers are applied 3i of the additive manufacturing process aufei ^¬ Nander here. In the example shown, the proportion of the high-melting component thus increases steadily from layer to layer and is essentially constant within the respective layer 3i. This can be easily achieved by adjusting the composition of the powder separately for each layer. The front shown in Figure 5

So here end face has the highest proportion of hochschmel ^¬ zendem material and may be advantageous in this example, be a thermally and / or mechanically particularly heavily loaded in use of the molding surface.

As an alternative to the example shown in FIG. 5, a concentration gradient can also be achieved in that the -

Composition of the starting material serving powder is changed within a layer after a predetermined spatial distribution. The composition of the powder can thus be varied within the layers and / or from layer to layer. In both directions, it can be varied either continuously or by leaps and bounds.

FIG. 6 shows a schematic cross-sectional illustration of a switching contact 13 for an electrical switch. The switching contact includes two contact elements 11, each ^¬ weils comprise a contact body and a contact carrier IIa IIb. The contact bodies IIa are formed from electrically conductive material and each have a contact surface 19, wherein these two contact surfaces 19 can be reversibly mitei ^¬ nander brought into electrical contact. By not shown here in detail mechanical elements of the Schaltkon ^¬ clock, the two contact elements 11 can thus be moved toward and away from each other. The two contact bodies IIa are each mechanically held by an associated contact carrier IIb. In this case, the contact carrier IIb may also be formed significantly larger in relation to the contact bodies IIa as shown in Figure 6. Ins ^¬ particular the contact carrier can each be larger than the contact body arranged thereon. The respective contact carrier can also be electrically conductive, but this is not absolutely necessary.

In the illustrated embodiment of Figure 1, the two contact bodies IIa as well as the two contact carrier IIb produced as a shaped body by the manufacturing method according to the invention. These parts of the two contact elements have been placed ^¬ builds thus in each case by layered application and solidification of powder by means of an additive manufacturing process. Alternatively, only the respective contact body IIa or only the respective contact carrier IIb may have been constructed with such an additive manufacturing method. Or it is also possible that only one of the two contact elements, so either only the lower or only the upper Contact element 11 is wholly or partially constructed by such addi ^¬ tive manufacturing method.

The contact surfaces 19 of the two contact bodies IIa each have a bent portion 21, wherein the curvatures in these portions are coordinated with each other so that the two contact bodies IIa can engage with each other. When the switch is closed, the largest possible and stable electrical contact is formed. Upon opening of the switch contact 13, a circuit ^¬ arc between the two contact surfaces 19 can be formed. In the left-hand area of FIG. 6, only the upper of the two contact bodies has an edge 20 at the edge of the contact surfaces 19. The contact body IIa shown below has in this area a rounded surface 21, whereby a formed in the area ^¬ sem switching arc can tear quickly. In general, the material of the two contact bodies IIa in the region of the contact surfaces 19 and in particular in the region of the edge 20 is particularly strongly thermally stressed by the formation of switching arcs. The contact bodies IIa are formed as ^¬ forth here so that, in the region of the contact surfaces 19 and especially in the region of the edges 20 a higher is present by ^¬-average concentration of a high-melting material component than in the more inner Berei- chen 23rd

Have the contact body IIa of the sixth embodiment Kgs ^¬ NEN silver or copper as the low melting point component and tungsten, tungsten carbide and / or chromium as a high melting point component. The average content of the high melting component ^¬ can thereby increase in the direction of the contact surfaces 19 of either approximately continuously or in discrete steps. Alternatively or additionally, it can continue to rise on the contact surface 19 in the direction of the edge 20. A structuring of the contact bodies 10a and 10b into individual layers applied in an additive manner is not shown in FIG. 6, since such layers may be visible on a macroscopic component only under microscopic observation are. The orientation of these layers may, for example, be parallel to the planar regions of the contact surfaces. However, the layers may also be perpendicular to these parts of the contact surfaces or include another angle with them.

Figure 7 shows a further embodiment of the invention, in which the molded body produced by this invention is a door ^¬ binenschaufel 31 of a gas turbine. Shown is a cross-sectional view of a ^¬ such a turbine blade having a plurality of cavities 33 in its interior. Such a ^turbine blade having such or may also significant more complex shape can be produced advantageously by a method of additive manufacturing. The material of the turbine blade 31 may in this case comprise a high proportion of a nickel-based alloy. By means of the method according to the invention, it can be achieved that a turbine blade 31 with a high proportion of such a thermally stable alloy can nevertheless be built up additively as a complex-shaped and mechanically strong component.

Figure 8 shows a further embodiment of the invention, in which the shaped body according to the invention produced a Fila ^¬ ment 41 is a lamp. In addition to the actual filament 41, two contacts 43 are shown, between which an electric current can flow. The filament advantageously has a comparatively high proportion of tungsten in order to ensure high thermal stability during operation. By the inventive manufacturing method ER may be sufficient that such a filament having a high proportion of such a high melting point component can be built as a complex shaped and mechanically resistant component additively on ^¬ still 41st

Claims

claims 1. A process for producing a shaped body (1), in which - Several superimposed material layers (3i) of Formed body (1) by means of an additive Fertigungsverfah ^¬ rens in a plurality of successive and mutually similar sub-steps,  - In each sub-step, a powder to a solid  Layer (3i) is solidified - And wherein the powder comprises a plurality of particles (5), each having at least one inner core (7) and a core substantially enclosing shell (9). 2. The method of claim 1, wherein the shells (9) of the Particles (5) have an average volume fraction of we ^¬ nigstens 10% of the average total volume of a ^¬ individual particles. 3. The method according to any one of the preceding claims, wherein the cores (7) of the particles (5) comprise at least one material (A), which as such at a process temperature of 1400 ° C is not sintered. 4. The method of claim 3, wherein the material (A) of the cores (7) is present at a process temperature of 1400 ° C in solid form and / or decomposes and / or reacts with air. 5. The method according to any one of the preceding claims, wherein the cores (7) of the particles (5) comprise at least one above 1700 ° C melting material (A), in particular a material (A) from the group of refractory metals, ceramics, glasses , Carbon fibers, borides or carbides. 6. The method according to any one of the preceding claims, wherein the shells (9) of the particles (5) comprise a below 1400 ° C melting material. 7. The method according to any one of the preceding claims, wherein the shells (9) of the particles (5) melt at a lower temperature Tempe ^¬ than the cores (7). 8. The method according to any one of the preceding claims, wherein the additive manufacturing method comprising a process step of La ^¬ serstrahlschweißens, laser melting, Laserstrahlsin- terns, the laser metal deposition, laser cladding, electron beam welding and / or electron beam ^¬ melting. 9. The method according to any one of the preceding claims, wherein the shells (9) of the particles each have at least two koncentric, the core (7) substantially enclosing Teilscha ^¬ len (9a, 9b). 10. The method according to any one of the preceding claims, wherein the shell (9) has at least two material components (A, B), wherein in particular a concentration of the two material components (A, B) in dependence on a distance (r) to the center (z ) of the respective particle (5) varies. 11. The method according to any one of the preceding claims, wherein the particles (5) each have a plurality of internal Ker ^¬ ne (7i) within a common shell (9), wherein the cores (7i) are each individual nanoparticles. 12. The method according to any one of the preceding claims, wherein for a plurality of the particles (5) of the core (7) has an im Has substantially aspherical shape and the shell has a substantially spherical shape. 13. powder of a plurality of particles (5) for producing a molded article (1) by a method according to one of Claims 1 to 12, - Wherein the particles (5) each have at least one innenlie ^¬ ing core (7) and the core (7) substantially enclosing shell (9),  - wherein the shells (9) of the particles (5) comprise a below 1400 ° C melting material (B) - and wherein the cores of the particles at least one material (A) which which is not sinterable as such at a process Tempe ^¬ temperature of 1400 ° C. 14. Shaped body (1), which is produced by a method according to one of claims 1 to 12. 15. Shaped body (1) according to claim 14, which has at least two material components (A, B) for which there is a concentration gradient in at least one spatial direction (x) in at least one part of the shaped body (1).