EP2781622A1 - Generative method particularly for producing a coating, device for carrying out the method, coating and a component manufacturing method and a component - Google Patents

Abstract

The method involves providing solidification by a beam melting method, such as laser-beam or electron-beam sintering method. The powder material mixture is comprised with first powder (100) and second powder (200). The content of second powder is continuously increased from the initial layer (21) to the last layer (25). The second powder is comprised with high temperature properties such as wear resistance and/or oxidation resistance and/or a low coefficient of thermal expansion with respect to high temperatures. Independent claims are included for the following: (1) device for producing coating; (2) coating for manufacture or repair of component; and (3) component manufacturing method.

Description

The invention relates to a generative process, in particular for the production of a coating, to a device for carrying out the process and to a coating. Furthermore, the invention relates to a component manufacturing method and a component.

A rotor of a turbomachine, for example a rotor of a gas turbine or steam turbine, has a rotor main body and a plurality of blades mounted on the rotor main body. Each blade has a blade root and an airfoil and a tip and is mounted with the blade root in a corresponding recess of the rotor body. However, due to the high temperatures in a gas turbine, cooling is often insufficient, especially at the blade tip. Especially at the blade tip a temperature difference of about 100 ° Celsius is present. Therefore occurs in the blade tip by the thermal and mechanical stress, in particular by shrinkage in so-called counter-sealing surfaces, often wear on. Cracking on the blade tip is the result. So far, the worn and / or torn region in the region of the blade tip was mechanically removed locally and restored by build-up welding with a filler material. However, this is very costly and time consuming. A longer life of a blade or blade tip is therefore desirable.

From the DE 103 19 494 A1 For example, a method of repairing a nozzle of a gas turbine is known in which a damaged portion is cut out of the nozzle to be repaired and a spare part for the cut-out portion is manufactured by means of a rapid manufacturing process becomes. The spare part produced by the rapid manufacturing process is integrated into the guide vane to be repaired by welding or soldering.

A first object of the invention is therefore to specify a generative method with which the above-mentioned problem can be reduced or even avoided. A second object is the disclosure of a device for carrying out the method. A third task is to specify a coating that solves the above problem. A fourth and a fifth object are the specification of a component production method and a component which solves the above-mentioned problem.

• Auftragen einer ersten Schicht eines ersten Pulverwerkstoffgemisches und Verfestigen dieser ersten Schicht zu einem ersten Überzugsabschnitt;
• Auftragen einer zweiten Schicht eines zweiten Pulverwerkstoffgemisches auf den hergestellten ersten Überzugsabschnitt und Verfestigen dieser zweiten Schicht zu einem neuen Überzugsabschnitt;
• sukzessives Auftragen von weiteren Schichten aus Pulverwerkstoffgemischen auf den jeweils hergestellten neuen Überzugsabschnitt und sukzessives Verfestigen dieser weiteren Schichten zu einem jeweils neuen Überzugsabschnitt, bis zu einer vorbestimmten letzten Schicht mit einem letzten Pulverwerkstoffgemisch sowie Verfestigen der letzten Schicht zu einem Überzug, wobei das Verfestigen durch ein Strahlschmelzverfahren, vorzugsweise als ein Laser- oder Elektronenstrahlsinterverfahren, vorgesehen ist;
• wobei das Pulverwerkstoffgemisch zumindest ein erstes Pulver und ein zweites Pulver umfasst, wobei der Anteil des zweiten Pulvers von der ersten Schicht bis zur letzten Schicht kontinuierlich zunimmt;
• und wobei das zweite Pulver in Bezug auf hohe Temperaturen geeignete Eigenschaften, insbesondere Verschleißbeständigkeit und/oder Oxidationsbeständigkeit und/oder einen geringen Wärmeausdehnungskoeffizienten in Bezug auf hohe Temperaturen aufweist.

According to the invention, the first object is achieved by specifying a generative method with the following steps:

• Applying a first layer of a first powder material mixture and solidifying said first layer to a first coating section;
• Applying a second layer of a second powder material mixture to the prepared first coating section and solidifying this second layer to a new coating section;
• successive application of further layers of powder material mixtures to the respectively produced new coating section and successive solidification of these further layers to a respective new coating section, up to a predetermined last layer with a final powder material mixture and solidification of the last layer into a coating, the solidification by a jet melting process , preferably as a laser or electron beam sintering method;
• wherein the powder material mixture comprises at least a first powder and a second powder, wherein the proportion of the second powder continuously increases from the first layer to the last layer;
• and wherein the second powder has suitable properties with regard to high temperatures, in particular wear resistance and / or oxidation resistance and / or a low thermal expansion coefficient with respect to high temperatures.

According to the invention, it has been recognized that components which are exposed directly to hot gas have regions which have a high temperature difference during the operating stress. Therefore, there are various requirements for the base material of these components, especially in these areas. According to the invention, coatings can be produced with this process which, due to the increase in the second powder to the last layer, meet these thermal requirements. Thus, the second powder may be locally characterized by a high wear resistance and / or oxidation resistance and / or a low thermal expansion coefficient with respect to high temperatures. Since the proportion of the second powder in the powder material mixture was increased continuously with increasing number of layers, this means that the mechanical and / or thermal properties change continuously with increasing layer. This also means that the thermal expansion due to the higher temperature in, for example, the last layer is the same as on the first layer, although this layer is directly exposed to the hot gas or the higher temperatures. In the optimal case, this means a complete compensation of the thermo-mechanical stresses in the coating.

The proportion of the second powder in the first layer is preferably 0%. In a preferred embodiment, the proportion of the first powder in the last layer is 0%. Thus, the appropriate properties of the second powder are maximized with respect to high temperatures.

• zumindest ein erster Pulverförderer mit einem verfestigbaren Pulver vorgesehen ist,
• zumindest ein zweiter Pulverförderer mit einem verfestigbaren Pulver vorgesehen ist,
• wobei sich die zumindest zwei Pulverförderer separat ansteuern lassen, so dass sich die zumindest beiden, verfestigbaren Pulver in einem beliebigen Verhältnis mischen lassen.

According to the invention, the second object is achieved by specifying a device for carrying out the above method, wherein:

• at least one first powder conveyor with a solidifiable powder is provided,
• at least a second powder conveyor is provided with a solidifiable powder,
• wherein the at least two powder conveyors can be controlled separately so that the at least two solidifiable powders can be mixed in any ratio.

By the device according to the invention, the method described above can be carried out very easily and easily.

According to the invention, the third object is to specify a coating for producing or repairing a component, in particular that of a fluid-flow machine comprising at least a first layer with a first solidifiable powder material mixture and a last layer with a last solidifiable powder material mixture, wherein between the first and the last layer a defined number of further layers of solidifiable powder material mixtures is provided, solved. In this case, the solidifiable powder material mixture of at least a first powder and a second powder, wherein the proportion of the second powder from the first layer to the last layer increases continuously and wherein the second powder with respect to high temperatures suitable properties, in particular wear resistance and / or oxidation resistance and / or a low thermal expansion coefficient with respect to high temperatures.

According to the invention, therefore, a coating is created which has different properties due to the different powder composition in different areas. By a continuous increase of the second powder, the change Properties also not abrupt, but slowly merge into each other or change continuously. In power plant technology, in particular when used in a gas turbine, the coating is thus adapted, for example, to the different thermal expansion coefficients or to the expected temperature gradients. This means that the thermal expansion due to the higher temperature in, for example, the last layer is the same as the first layer, although this layer is directly exposed to the hot gas or the higher temperatures. In the optimal case, this means a complete compensation of the thermo-mechanical stresses. Due to the properties such as wear resistance and / or oxidation resistance, such a coating is therefore particularly suitable for use in power plants.

Preferably, the proportion of the second powder in the first layer is 0%. In particular, the proportion of the first powder in the last layer is 0%. Thus, the appropriate properties of the second powder are maximized with respect to high temperatures.

The coating is preferably produced by the above-mentioned generative process and / or the above-mentioned device. As a result, the coating can be produced particularly easily.

• Zuschnitt des Überzugs auf das Basisbauteil,
• Verbinden des Überzugs und des Basisbauteils zu einem Endbauteil,
• Rekonturierung des Endbauteils durch Nachbearbeitung.

According to the invention, the third object is achieved by specifying a component production method, in particular for repairing a component, comprising a base component and an abovementioned coating, characterized by the following steps:

• Cutting the coating onto the base component,
• Bonding the cover and the base member to an end member,
• Re-contouring of the final component by post-processing.

The component manufacturing process according to the invention now makes repair of e.g. High-temperature loaded components with a suitable coating possible. The coating can be manufactured separately and on / in-place of the component to be repaired on / in this. Of course, an application to the new part is possible; For example, a blade can be cast without a tip and the tip made from a coating. As a result, a particularly temperature-resistant blade can be manufactured with a long service life.

The joining preferably takes place by joining, in particular friction welding. But it can also be used any other welding / joining process.

In a preferred embodiment, abrasion occurs by the connection by friction welding of the coating and the base component. The recontouring of the end component includes the post-processing of the abrasion by mechanical processing, in particular by turning or milling. This can be done very easily.

In a preferred embodiment, the coating is heat treated prior to bonding to the base member. This can be, for example, a hot isostatic pressing (HIP process) to set the optimum mechanical properties and, where appropriate, to eliminate hot cracks. Preferably, the final component is heat-treated, so that the structure gets the optimal properties.

According to the invention, the fourth object is achieved by specifying a component which is repaired or manufactured according to the above component manufacturing method.

This may in particular be a component of a gas turbine, for example a blade. In this case, the blade at its tip, which is formed by the last layer, a large proportion of the second powder, which, for example, a thermal is highly resilient material. For example, the thermal expansion coefficient at the tip of the component or the coating can be adapted to the expected temperature gradients. Of course, the second powder may also have other or additional properties.

Preferably, the first powder has similar or the same material properties as the base component. If the thermal expansion is chosen as the material property, then it can be adjusted by means of this combination that the thermal expansion due to the higher temperature at the last layer (top) of the coating is just as great as in the first layer of the coating, although between the tip and the first Layer of the coating is a large temperature gradient. This means a complete compensation of the thermo-mechanical stresses.

FIG 1:

eine Turbinenschaufel mit Riss,

FIG 2:

einen erfindungsgemäßen Überzug und einen Basisflügel,

FIG 3:

Verbinden des erfindungsgemäßen Überzugs mit einem Basisflügel,

FIG 4:

zwei Pulverförderer mit Mischdüse.

Further features, properties and advantages of the present invention will become apparent from the following description with reference to the accompanying figures. In it show schematically:

FIG. 1:

a turbine blade with crack,

2:

a coating according to the invention and a base wing,

3

Bonding the coating according to the invention to a base wing,

4:

two powder conveyors with mixing nozzle.

FIG. 1 shows a turbine blade 1 with a wing profile 3 according to the prior art. This has a blade root 2. In addition, the blade 1 comprises a tip 4, which has a crown 5 with an inner crown bottom 6 and an outer crown edge 7. The turbine blade 1 is designed to rotate within a housing (not shown). It is important that the blade tip 4 fits precisely into the housing (not shown) so as to prevent an outward flow of the combustion gases on the blade tip 4 as far as possible, since the gases taking this bypass no energy transferred to the airfoil 3 of the blade 1.

The blade 1 may have a thermal barrier coating at its tip. Nevertheless, one or more cracks 10 may occur in the crown 5 of the turbine bucket 1, due to material fatigue at low load cycles occurring during operation of the turbine and acting on the bucket tip 4. If a crack 10 exceeds a critical length, the turbine blade 1 must be taken out of service and / or repaired. So far, cracks 10, unless they exceed a critical length, have been laser-deposited, e.g. with the filler or by e.g. Tungsten inert gas welding (TIG welding) repaired.

Due to the temperature difference between the crown bottom 6 and the crown edge 7 during the operating stress resulting for the blade repair or a new part production different requirements for the material. According to the invention, it has been recognized that the material on the crown bottom 6, that is to say at the transition from the airfoil 3 to the crown 5, should be approximately identical to the material of the airfoil 3, so that different thermal expansion coefficients do not lead to critical loads during the heating phase or cooling phase during operation of the turbine blade 1 lead. At the crown edge 7 of the tip 4 a high resistance to wear and oxidation resistance is required locally, which can not be reconciled with the chemical / metallurgical composition of the airfoil 3.

FIG. 2 shows a coating 35 according to the invention, which can be used to repair the blade tip 4. For this purpose, the blade tip 4 can first be completely removed, so that a base wing 15, which may be identical to the wing profile 3, remains. The coating 35 comprises at least a first layer 21 with a first solidified powder material mixture and a last layer 25 comprising a last consolidated powder material mixture, and between the first and the last layer 25 a defined number of further layers 22-24, wherein the number is not fixed here to three. Of course, the number can be zero, of course; ie no further layer can be provided.

In this case, the solidified powder material mixture consists of at least a first powder 100 and a second powder 200, wherein the proportion of the second powder 200 from the first layer 21 to the last layer 25 increases. This can be a continuous steady increase for very fine layers 21-25. Of course, the powder material mixture can also consist of several powders. Here, the first layer 21, which is later connected to a base member here a base wing 15, initially only a first powder 100. This first powder 100 is later or when applied to a first, solidified powder 100. The powder 100 or solidified powder 100 is similar or equal to the material and / or has similar or the same properties as the base wing 15. In this case is to be mentioned as a similar or identical property, especially the thermal expansion coefficient. For example, the powder 100 is applied to a mold 50 (FIG. FIG. 4 ) and then solidified into a first coating section 31. Also, the mold 50 ( FIG. 4 ) Of course, the base wing 15 itself.

In the subsequent layers 22-24, at least one second powder 200 is added to the first powder 100 to form a second powder material mixture. By applying the second powder material mixture to the produced first coating section 31, a second layer 22 is generated, which subsequently solidifies with the first coating section 31 to form a new coating section 32. The subsequent layers 23 and 24 are successively applied to the coating sections 32 and 33 produced analogously thereto. The last layer 25 is therefore applied to a coating section 34.

The powder 200 now has properties which are required in particular for high temperatures. According to the invention, the proportion of powder 200 in the powder material mixture is increased as the number of layers increases. The last layer 25, ie the layer which is exposed directly to the hot temperature, in particular by hot gas, consists essentially only of the powder 200, which is subsequently solidified or applied. The solidified powder 200 is later exposed directly to the hot gas or the hot temperatures. The solidified powder 200 of the last layer 25 represents the crown edge 7, so to speak later. In this case, the solidified powder 200 now has properties which are required in particular for high temperatures. These are mainly wear resistance and oxidation resistance and a low coefficient of thermal expansion. Since the proportion of powder 200 in the powder material mixture was continuously increased with increasing number of layers, this means that the mechanical and / or thermal properties change continuously with increasing layer. The blade tip 4 is therefore made graduated.

Of course, more than two powders 100 and 200 can be mixed together. The mixture of the at least two powders 100 and powders 200 can be effected by two separately controllable powder conveyors 101 and 201 and a coaxial mixing nozzle 70 ( FIG. 4 ). By the separate driving of the powder conveyors 101 and 201 ( FIG. 4 ), the powder material mixture can be mixed in any ratio. Subsequently, the mixture is applied to a mold 50 (FIG. FIG. 4 ) applied and solidified.

Since the last layer 25 is directly exposed to the hot gas or temperatures, the last solidified powder 200 also requires a low coefficient of thermal expansion than the layer 21 of the first solidified powder 100 and the base wing 15 in such a way that the thermal expansion at the last layer 25 is the same as at the first layer 21. This, and the continuous change of the mechanical and / or thermal properties with increasing layer ideally lead to an almost complete Compensation of the thermal stresses in the operation of the blade 1 and reduced cracking.

The solidification of the layer can be done for example by welding. This can be, for example, a build-up welding or laser sintering / laser melting by means of a heat source 60 (FIG. FIG. 4 ) or another generative manufacturing process. The layers 21-25 are thus connected to one another in a material-locking manner and thereby ultimately form the desired coating 35.

Subsequently, the coating 35 is cut to fit the base blade 15, for example, the blank of the coating 35 can be used as a replacement blade tip 30 (FIG. FIG. 3 ) be. Of course, the coating 35 can be tailored to any other component, such as heat shields or other parts in the power plant. An application is also conceivable outside of power plant technology. After cutting, the replacement blade tip 30 (FIG. FIG. 3 ), eg by hot isostatic pressing (HIP), to eliminate joining defects and to produce the optimum mechanical properties. Subsequently, the replacement blade tip 30 (FIG. FIG. 3 ) to the base bucket 15 ( FIG. 3 ) to a replacement vane 41 ( FIG. 3 In this case, the joining 12, for example by means of friction welding ( FIG. 3 ) or other known joining methods.

The resulting from the joining 12 abrasion or burrs or seams are remedied by a post-processing (re-contouring) by means of mechanical processing, such as milling or grinding. Subsequently, the replacement blade 41 (FIG. FIG. 3 ) are heat treated again.

Of course, it is also possible by means of the invention to produce new blades. For this purpose, the base blade 15 can be produced and continued as described above, or the complete blade 1 (FIG. FIG. 1 ) graduated as described above. Of course, other components such as burners, heat shields, etc. can be manufactured or repaired with the invention. By means of the invention, it is possible to avoid or at least reduce the thermo-mechanical stress during operation in the case of components subject to high temperatures. Cracking or degradation can thus be avoided. The components thus have a much longer life.

Claims (15)

Generative process, in particular for producing a coating (35), comprising the following steps: - Applying a first layer (21) of a first powder material mixture and solidifying this first layer to a first coating portion (31); - applying a second layer (22) of a second powder material mixture on the prepared first coating section (31) and solidifying this second layer (22) to a new coating section (32); - Successive application of further layers (23-24) of powder material mixtures on each prepared new coating section (32-33) and successive solidification of these further layers (23-24) to a respective new coating section (33-34), up to a predetermined last layer (25) with a last powder material mixture and solidifying the last layer (25) into a coating (35), the solidification being provided by a jet melting process, preferably as a laser or electron beam sintering process; - And wherein the powder material mixture comprises at least a first powder (100) and a second powder (200), wherein the proportion of the second powder (200) from the first layer (21) to the last layer (25) increases continuously; - And wherein the second powder (200) with respect to high temperatures suitable properties, in particular wear resistance and / or oxidation resistance and / or has a low coefficient of thermal expansion with respect to high temperatures. Generative process for producing a coating (35) according to claim 1,
characterized in that the proportion of the second powder (200) in the first layer (21) is 0%. A generative process for producing a coating (35) according to claim 1 or 2,
characterized in that the proportion of the first powder (100) in the last layer (25) is 0%. Device for carrying out the method according to one of claims 1 to 3,
characterized in that t at least one first powder conveyor (101) with a solidifiable powder (100) is provided, at least one second powder conveyor (201) with a solidifiable powder (200) is provided, - Where the at least two powder conveyors (101,201) can be controlled separately, so that the at least two solidifiable powders (100, 200) can be mixed in any ratio. Coating (35) for producing or repairing a component, in particular that of a flow engine comprising at least a first layer (21) with a first solidifiable powder material mixture and a last layer (25) with a last solidifiable powder material mixture, wherein between the first (21) and the Last layer (25) is provided a defined number of further layers (22-24) of solidifiable powder material mixtures,
characterized in that the solidifiable powder material mixture consists of at least a first powder (100) and a second powder (200), wherein the proportion of the second powder (200) from the first layer (21) to the last layer (25) increases continuously and wherein the second powder (200) has suitable properties with respect to high temperatures, in particular wear resistance and / or oxidation resistance and / or a low thermal expansion coefficient with respect to high temperatures. Cover (35) according to claim 5,
Characterized t that the proportion of the second powder (200) in the first layer (21) is 0%. A cover (35) according to claim 5 or 6,
Characterized t that the proportion of the first powder (100) in the last layer (25) is 0%. A coating (35) according to any one of claims 5 to 7, which is manufactured by the additive method according to claims 1 and 3 and / or the device according to claim 4. Component manufacturing method, in particular for repairing a component, comprising a base component (15) and a coating (35) according to one of claims 5 to 8, characterized by
following steps: Cutting the coating (35) onto the base component (15), Bonding the coating (35) and the base component (15) to an end component, - Rekonturierung of the final component by reworking. Component manufacturing method according to claim 9, in particular for repairing a component,
characterized in that the joining takes place by joining (12), in particular friction welding. Component manufacturing method according to claim 10,
characterized in that by joining the coating (35) and the base member (15) by friction welding abrasion occurs and the recontouring of the end component, the post-processing of the Abrasion by mechanical processing, in particular by turning or milling, includes. Component manufacturing method according to one of claims 9 to 11,
characterized in that the coating (35) is heat treated prior to bonding to the base member (15). Component manufacturing method according to one of claims 9 to 12,
characterized in that the end member is heat treated. Component which is repaired or manufactured according to a component manufacturing method according to at least one of claims 9 to 13. Component according to claim 14,
characterized in that the first powder (100) has similar or the same material properties as the base member (15).

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