WO2008125497A1

WO2008125497A1 - Method for the production of high temperature components, and a component produced thereby

Info

Publication number: WO2008125497A1
Application number: PCT/EP2008/053946
Authority: WO
Inventors: Lluis Gimeno-Fabra; Johannes Vlcek
Original assignee: Eads Deutschland Gmbh
Priority date: 2007-04-16
Filing date: 2008-04-02
Publication date: 2008-10-23
Also published as: DE102007018126A1

Abstract

The invention relates to a method for the production of components, particularly for high temperature uses, made of a material which contains at least one metal with a melting point of over 2000°C. For this purpose, a starting material of a powder containing the desired material is melted selectively and subsequently permitted to solidify, wherein the component with the desired final contour is built up layer by layer, preferably by electron beam sintering.

Description

Production method for high-temperature components and component produced therewith

The invention relates to a method for producing components according to the preamble of claim 1 appended hereto, as known from US Pat. No. 5,352,538. This document will be discussed in more detail below.

Accordingly, the invention relates to a method for producing components, in particular for high temperature applications, from a material containing at least one metal having a melting point of above about 2000 ⁰ C. In a preferred embodiment, the invention relates to a production method for high temperature components made of an alloy, in particular of a binary alloy.

From the aforementioned US Pat. No. 5,352,538 A, a method for producing an aluminum component having a hardened surface is known, wherein powdered alloy material is melted by means of a laser to produce the surface to be hardened on an aluminum substrate. This process takes place in several layers. The powder may be a metal-aluminum mixture.

A method for producing components for high-temperature applications is known from DE 103 40 132 A1. This document relates to an oxidation-resistant, ductile CrRe alloy for high-temperature applications and a corresponding CrRe material. More specifically, the document DE 103 40 132 A1 describes a special high-temperature alloy which is suitable for applications where structural materials with very good oxidation and Corrosion resistance and good mechanical properties are required, which can work in temperature ranges above 1000 ⁰ C. For example, such components are suitable for use in satellite, aircraft or jet engines. Other exemplary uses are thermally highly stressed components of missiles and heating plants, to name just a few examples.

Due to desired mechanical properties, a component of high-temperature metals is advantageous for such fields of application. The prior art according to DE 103 40 132 A1 proposes a chromium-rhenium alloy for this purpose.

High temperature metals have a high melting point per se. The high melting point is also in the production of metal alloys from high temperature metals process engineering problems. In particular, there are considerable difficulties in processing by the common melt metallurgy. High process temperatures are required. The process options are limited due to the process conditions to be complied with. When the melt is heated at very high temperatures, there is a risk of contamination by the crucible material. These problems occur in particular in materials that should contain metals with a melting point above about 2000 ⁰ C.

Furthermore, such high-temperature metals and alloys formed therefrom have special material properties, which are characterized by the microstructure and high hardness and strength. This results in considerable difficulties in the machining, so that only specific cutting materials, such as hard metals or cutting ceramics, can be used. In addition, it is difficult to ensure the homogeneity of alloys or other composite materials containing the high-temperature metals.

The invention has therefore set itself the task of improving a method for producing components, in particular for high-temperature applications, from a material containing at least one metal having a melting point of above about 2000 ⁰ C, such that complicated components easier and cheaper and can be produced in improved quality.

This object is achieved by a method having the features of claim 1.

Advantageous embodiments of the invention are the subject of the dependent claims.

A thermally highly loadable component (e.g., an engine component or a Cr-Re component) manufacturable therewith is the subject of the subsidiary claims.

In the method according to the invention, a powder containing starting materials of the desired component material is selectively melted and then allowed to solidify, the component having the desired final contour being built up in layers. The starting material is here as a powder, which contains the constituents of the desired component material, and is locally melted and then solidifies again quickly. The location of the reflow is varied until a layer of the component is produced with corresponding outer contours. The next layer is then applied in a corresponding manner via this layer. In this way, the component with the desired final contour is built up in layers using 3D CAD data.

As a blueprint for the variation of the place of local warming or

Melting serve in particular data which corresponds to the desired final contour of the Correspond to components. This data can advantageously come from 3D CAD files.

Such processes for the "direct construction" of metallic structures with the desired final contour are known in the art under a variety of names or designations - "direct metal sintering" (DMS), "powder metal sintering", "laser assisted metal sintering,""fusing" or "near net shaping", "solid free form fabrication (SF ³ )" etc. - which can also be summarized under the term "rapid prototyping" or "rapid manufacturing". The term "rapid prototyping" is usually used in the production of individual prototypes and comes from the area of the production of prototypes made of plastics.When producing larger quantities, the term "rapid manufacturing" is often used in recent times, which is particularly expressed should bring that the process in the (vision) production is used together with the series material. As a heat source for melting or sintering of

Starting material typically uses lasers, electron beams or other suitable heat sources.

According to one embodiment of the invention, in the method according to the invention, a beam of high-energy radiation is passed over the powder, a powder mixture of alloying constituents, for example chromium and rhenium, and possibly one or more further constituents, in order to produce correspondingly 3D CAD data. Data build the component with desired final contour in layers.

With the method according to the invention can thus directly from a powder mixture as the starting material to produce a high-temperature alloy directly with the desired component contour.

The process may be carried out in vacuo (eg if an electron beam is used as the heat source) or under a special inert gas atmosphere or inert gas atmosphere, such as under an argon / helium atmosphere, for example. be performed. The latter occurs in particular when a laser is used as the heat source. The use of an inert gas or inert gas atmosphere under a pressure greater than 10 ⁵ Pa is particularly advantageous in the processing of chromium, since the chromium then does not evaporate so quickly.

Particularly preferred material used for the component to be produced is a high-temperature alloy which contains as an essential constituent at least one metal melting above 2000 ^° C. (eg niobium, molybdenum, tungsten, tantalum and / or rhenium), the powder of powder particles being more desirable Alloy components is mixed.

According to a further preferred embodiment, the pul verförmiger starting material a mixture of at least one of above about 2000 ⁰ C melting component (for example, niobium, molybdenum, tungsten, tantalum, and / or rhenium) and at least one melting at a lower temperature component (for example, copper , Iron, aluminum, chromium, nickel and / or cobalt).

Since the individual constituents of the pulverulent starting material have different melting temperatures, the low melting point constituents will first melt and the very high melting point constituents melt later, or possibly not at all, unless the melting temperature is reached by the heat source used. Consequently, in the method according to the invention, at least one component of the

However, the term "selective melting" does not exclude that all constituents of the starting material can reach the melting point, and thus a completely liquid Phase is present, which may be particularly advantageous for improving the structural homogeneity. In the case of selective melting, the low-melting constituent thus first becomes liquid. In the then forming solid-liquid mixture then the high-melting component can be distributed homogeneously. This is done, for example, by diffusion.

To aid in diffusion, a much lower melting point ingredient is advantageous. For example, the powder material could also be accompanied by a light metal.

It is advantageous to select powder mixtures of different constituents, powder particle sizes and process parameters, which achieve the most homogeneous possible melting.

For the production of chromium rhenium components, however, it has been shown that it is advantageous if both components - chromium and rhenium - melt, since then creates a particularly homogeneous structure. In this case, a powder mixture of chromium powder, rhenium powder and possibly one or more further constituents is used.

To produce tantalum-tungsten components, a powder mixture of tantalum powder, tungsten powder and possibly one or more further constituents is used.

For the production of molybdenum-rhenium components, a powder mixture of molybdenum powder, rhenium powder and possibly one or more further constituents is used.

Advantageously, the components produced according to the invention consist of a material with more than 40 wt .-% of a melt above 2000 ⁰ C metal. A powder is preferably used which contains 45-75% by weight of rhenium, 25-55% by weight of chromium and 0.05-5% by weight of at least one element from the group consisting of scandium, cerium and praseodymium. Optionally, the powder contains at least one of the following elements: magnesium with a maximum of 5% by weight, carbon with a maximum of 0.5% by weight and aluminum with a maximum of 8% by weight.

The advantages of the invention and / or its advantageous embodiments are as follows:

• Parts with a high machining ratio, such as lattice blades or large engines and large engine components, can be manufactured cost-effectively.

The selectively melted starting material undergoes rapid cooling in the process so that segregation, as occurs in casting processes, is prevented. This leads to better material properties.

• In the method according to the invention there are no impurities by crucibles or the like.

• Raw materials, such as metal powders shown in chemical precipitation reactions, can be processed directly.

Embodiments of the invention will be explained in more detail with reference to the accompanying drawings.

It shows

Figure 1 is a schematic overview of an apparatus for the direct construction of components made of high temperature metals and in particular of high temperature metal alloys.

FIG. 2 shows a sequence of images for illustrating the method principle; FIG. and 3 is a perspective view of a detail of the apparatus of FIG .. 1

In Fig. 1 a generally designated by reference numeral 10 device for carrying out the method according to the invention is shown schematically. The method according to the invention will be described below by way of example with reference to an electron beam sintering method. The apparatus 10 includes an electron gun 12 configured to direct an electron beam 14, controlled by a controller 16, such as a computer, to any predefined positions of a powder bed 18. This is indicated here by a schematically illustrated movement mechanism 20, which is the

Electron beam generating device 12 in both horizontal directions - x-direction and y-direction - can move. The movement mechanism 20 is shown only as an example. A scanning of the electron beam 14 over the entire surface of a parts platform 22, on which a component 24 is to be produced, can also be carried out, for example, advantageously by known electron beam optics with a fixed beam generating device. These techniques are known and will not be discussed further here.

The powder bed 18 is formed by the part platform 22, which is movable in the z-direction by the controller 16 controlled by a motor 26, and by a frame 28 in which the part platform 22 is guided so that in the frame 28 above the parts platform a loose powder 30 is received.

Furthermore, a coating device 32 is provided, which can be moved over the powder bed 18 in order to apply a new layer of powder 30.

The powder bed 18 with the coating device 32 is located in a space 34, which can be evacuated and / or via a supply line 36 with valve 40 with certain gas atmospheres, for example, with an argon / helium atmosphere, can be filled. The vorerläuterten actuators of the device 10 are controlled by the controller 16 based on data for the construction of the component 24. The data is provided by a CAD system 42 as 3D CAD data of the component 24 to be manufactured.

With the device 10, a direct structure of the component 24 can be carried out with the desired final contour, wherein the component 24 is constructed layer by layer or layer by layer. In this case, powdery starting material - powder 30 - locally heated by the electron beam 14 or other suitable heat source and selectively melted depending on the melting temperature of the powder components; i.e. at least the powder components with a low melting point pass into the liquid phase, and then quickly solidify again. In this way, the resulting material is built up in layers on the parts platform 22, so as to build a component 24 with the desired final contour.

In this case, with the present data information of the 3D CAD model 44 from the CAD system 42, the component 24 is generated step by step in the powder bed 18. The data control the electron beam 14 along the component cross-section. Layer by layer, the processing takes place by a certain thickness, for example by a thickness of 0.02 to 0.2 mm.

After a layer is completed, the part platform 22 is lowered by the motor 26. The coating device 32 travels over the powder bed 18 and provides a quantity of powder for a further layer.

The energy supplied by the electron beam 14 is absorbed by the powder 30. Thereby, the powder is heated, whereby first a connection (ie fixing) of the powder particles is created and then the powder, as already described above, is selectively melted. Subsequently, the material solidifies again, which leads to a local solidification of the material. This method is shown in Fig. 2 in more detail. Reference numeral 46 designates the image of a computer monitor, for example of the monitor 48 shown in FIG. 1, with the 3D CAD model 44 of a component 24. The device 10 then builds the component 24 as described above (see step 50). The rightmost partial view of Fig. 2 shows the finished component 24th

FIG. 3 shows a perspective view of the powder bed 18 with the layered structure of a region of the component 24. As shown, the component cross section is scanned in one layer by methods in the x-direction and in the overlying layer by a method in the y-direction ,

With the reference numeral 52, the diameter of the electron beam 14 is illustrated. The scanning is performed such that the individual scanning tracks 55 overlap by a certain amount 54. Reference numeral 56 denotes the thickness of the individual layers 58. The Abtastspuren run in mutually adjacent layers 58 crosswise to each other, d. H. in a layer is a sampling z. B. in the x direction, in the following in the y direction, in the third layer then again in the x direction, u.s.w.

When an electron beam is used as the heat source, the process typically occurs under vacuum. With the electron beam 14, metals with high melting points are very easy to process. It is possible to generate higher process temperatures and / or higher component temperatures than with a laser. If the process is carried out with the aid of a laser, work is typically carried out in an argon and / or helium atmosphere.

By means of the method according to the invention, components of a chromium-rhenium alloy, for example, can be produced very well, the chromium content being, for example, 35% by weight and the rhenium content, for example, 65% by weight. Advantageously, components are made of alloys, as they are explained in DE 103 40 132 A1 closer. Reference is made expressly to DE 103 40 132 A1 for further details of the composition of these alloys as well as advantageous uses of the components 24 produced therewith.

Exemplary alloy compositions for corresponding Cr-Re alloys are shown in Table 1.

Element weight%

Re 45 - 75 55 - 70 60 - 70

Cr 55 - 25 45 - 30 40 - 30

AI 4 - 8

Sc, Ce, Pr 0.05 - 5 in total

Mg 0.1-5

C 0.05-0.5

Table 1

Further examples of high-temperature components produced according to the invention are those which consist of tantalum-tungsten alloys or molybdenum-rhenium alloys. It is particularly advantageous if the melting above 2000 ⁰ C component is at least 40 wt .-%.

The manufacturing method shown here for producing components 24 from high-temperature metals or high-temperature metal alloys has a number of advantages.

Thus, even with large components, homogeneity of the material over the entire component can be achieved with this method.

There is no segregation, as with slow cooling. There is a special variety of geometry achievable. It is also geometries that are not achievable by machining processes, unfavorable transitions from thick to very thin, such as on a grid wing, and also produce very filigree structures.

Several intermediate steps in the processing are avoided; For example, can be dispensed with the programming of NC programs or the production of EDM electrodes. A cleaning can be done after the process by blasting with similar powder or corundum.

It can generate so-called net-shape geometics; the components can be produced after only minor reworking. The lead times are very short.

The components 24 can be produced very quickly compared to previous manufacturing methods for such components.

Due to the use of a CAD-based system, design modifications can be implemented very quickly in production.

Particularly large components 24 were previously only limited production, since they were cast only conditionally. With the manufacturing process shown here, components with a size up to about DINA4 can be manufactured according to the plant development. The material consumption can ultimately be minimized. Especially with the very expensive materials to be used here, a substantial saving can be achieved.

In the case of the components produced by this process, the dispersoids are distributed very homogeneously.

Finally, it should be mentioned that for erfindungemäßen production of a high-temperature component and a method can be used in which a Powder jet is heated in a laser nozzle by means of a laser, and is generated in this way, layer by layer of the desired component with final contour. In other words, the present invention is not limited to the above-described embodiment.

LIST OF REFERENCE NUMBERS

10 Device for selective electron beam sintering

12 electron gun

14 electron beam

16 control

18 powder bed

20 movement mechanics

22 parts platform

24 component

26 engine

28 frame

30 powders

32 Coating device with powder

34 room

36 supply line

40 valve

42 CAD system

44 3D CAD model

46 Image of a computer monitor

48 monitor

50 electron beam sintering

52 pressure gauge of the jet

54 Measure of the overlap of the sintered tracks

55 scanning tracks (sinter traces)

56 thickness

58 layer

X x direction y y direction

Z z direction

Claims

New claims

A method of making components (24), particularly for high temperature applications, from a material containing at least one metal having a melting point above 2000 ^° C, wherein a powder (30) containing a source of the desired material is selectively melted and then solidified in that the component (24) having the desired final contour is built up in layers, characterized in that the component (24) is built up in layers on the basis of 3D CAD data (44).

2. The method according to claim 1, characterized in that the material is a high-temperature alloy containing as an essential ingredient at least one above 2000 ⁰ C melting metal, wherein the powder (30) is mixed with powder particles of desired alloying constituents.

3. The method according to claim 1 or 2, characterized in that the powder (30) is a mixture of at least one above 2000 ⁰ C melting component and at least one melting at a lower temperature component is used.

4. The method according to claim 2 or 3, characterized in that as

Component that melts above 2000 ⁰ C, niobium, molybdenum, tungsten, tantalum, and / or rhenium is used.

5. The method according to claim 3, characterized in that as a component which melts below 2000 ⁰ C, copper, iron, aluminum, chromium, nickel and / or cobalt is used.

6. The method according to any one of the preceding claims, characterized in that as a powder (30) A powder mixture of chromium powder, rhenium powder and possibly one or more further constituents is used to produce a Cr-Re alloy component;

A powder mixture of tantalum powder, tungsten powder and possibly one or more further constituents is used to produce a component of a Ta-W alloy, or

A powder mixture of molybdenum powder, rhenium powder and possibly one or more further constituents is used to produce a component of a Mo-Re alloy.

7. The method according to any one of the preceding claims, characterized in that thus components (24) are made of a material having more than 40% by weight of a melt above 2000 ⁰ C metal.

8. The method according to any one of the preceding claims, characterized in that the powder (30) contains:

45-75% by weight rhenium (Re),

• 25-55 wt.% Chromium (Cr) as well

0.05 to 5% by weight of at least one element of the group consisting of scandium (Sc), cerium (Ce) and praseodymium (Pr).

9. The method according to claim 7, characterized in that the powder (30) further contains at least one of the following elements:

Magnesium (Mg) with a maximum of 5% by weight,

• Carbon (C) with a maximum of 0.5 wt .-% and

• Aluminum (AI) with a maximum of 8 wt .-%.

10. The method according to any one of the preceding claims, characterized in that the selective melting is carried out under vacuum or a noble gas atmosphere.

11. The method according to any one of the preceding claims, characterized in that the powder (30) in layers over the cross section of a desired contour with at least one beam (14) of a selective Melting of the powdered latex material is scanned suitable high-energy radiation.

12. The method according to claim 10, characterized in that the scanning is carried out in subsequently produced layers (58) in different scanning directions (x, y).

13. The method according to any one of claims 10 or 11, characterized in that the scanning of the individual layers (58) takes place with overlapping Abtastspuren (55).

14. The method according to any one of the preceding claims, characterized in that the powder (30) is selectively melted by a laser or an electron beam.

15. Thermally highly resilient component, in particular engine component or lattice blade, for an aircraft or spacecraft or a device to be used outside the earth's atmosphere, produced by a method according to one of claims 1 - 14.

16. Chromium rhenium component, produced by a method according to one of claims 1-14.