Method for producing a component and/or a coating comprised of a vibration-damping alloy or intermetallic compound, and component produced using this method

Abstract

A method for producing a component and/or a coating from a vibration-damping alloy or intermetallic compound includes producing the component and/or the coating via thermal spraying.

Description

[0001] This application claims the priority of German application 102 08 868.3, filed Mar. 1, 2002, the disclosure of which is expressly incorporated by reference herein.

BACKGROUND AND SUMMARY OF THE INVENTION

[0002] The present invention relates to a method for producing a component and/or a coating comprised of a vibration-damping alloy or intermetallic compound. The invention also relates to a component produced using such a method.

[0003] Shape-memory alloys, as an example, are suitable for use in vibration damping, provided their structure is correspondingly designed.

[0004] Shape-memory alloys have long been known in the art. For example, German patent document DE 40 06 076 C1 describes a NiTi shape-memory alloy which, with a nearly stoichiometric composition, is characterized by an especially high degree of reversible deformation in one-way and two-way effects, high tensile strength and ductility, and a very high resistance to corrosion. Furthermore, this shape-memory alloy exhibits an outstanding degree of shape-memory effect stability with respect to thermal cycles. In addition, this alloy can be heated relatively far beyond the A1 temperature (temperature of the completion of austenite formation) without developing damaging irreversible structural changes which reduce the degree of shape-memory effect or undesirably shift the conversion temperature.

[0005] An iron-nickel-cobalt-titanium shape-memory alloy and a method for producing the alloy are known from German document DE 41 20 346 A1. According to this publication, the shape-memory alloy is produced via a casting method, after which it is deformed at temperatures of between 1,050° C. and 1,052° C., and then quenched; it is then subjected to a solution treatment over a period of 10 to 30 hours at temperatures of between 1,150° C. and 1,250° C. in an inert gas atmosphere, after which it is again quenched. To generate the shape-memory effect, the shape-memory alloy is exposed to temperatures of between 500° C. and 650° C. for a period of between 10 minutes and 150 hours, after which it is quenched for a third time and then subjected to training deformation involving one to fifty repetitions.

[0006] A method for producing Cu/Zn/Al-type shape-memory alloys via a powder-metallurgical process is known from WO 81/02587. In this method, the finished powder is encapsulated, cold-compressed, heat-compressed, and extruded. In practice, however, this method does not fulfill all necessary requirements, and the formed components often are inadequate in terms of their mechanical properties.

[0007] Another method known from this publication involves again producing the shape-memory alloy, via a powder-metallurgical process, as a fine-grained memory alloy of the Cu/Zn/Al type with a β-high temperature phase, and with dispersoids in the form of Y2O3 and/or TiO2 particles embedded in the matrix that serve to inhibit grain growth. The production process is accomplished with the help of mechanical alloying.

[0008] Further known shape-memory alloys are produced via a power-metallurgical process with a subsequent hot-isostatic pressure treatment, extrusion molding treatment, or forging treatment.

[0009] One object of this invention is to further develop a method for producing a component and/or a coating from a vibration-damping alloy or intermetallic compound such that the properties are improved, the range of application is expanded, and the production process is simplified.

[0010] This object is attained with respect to the method by producing the at least one of the compound and the coating via thermal spraying.

[0011] Further advantageous features of the invention are reflected in dependent claims.

[0012] Pursuant to the invention, a component and/or a coating are/is produced via a thermal spraying process. In this process, the metallic coating material is deposited on the surface of a carrier material or component in the form of heated and accelerated spray particles. Precise temperature control combined with a high particle speed results in formation of vibration-damping properties. In the thermal spraying process, for example, a solid object is coated with a heated and accelerated metallic material, which e.g. is fed into a thermal spray gun in the form of powder or wire. The surfaces of the solid object are not fused during the spray process. During spraying at temperatures >850° C., interdiffusion takes place between the component and the applied layer. Thus, at low coating temperatures, adhesion is preferably the result of physical interaction. A metallurgical linkage then occurs in conjunction with the coating process via diffusion annealing at temperatures >800° C. Precise temperature control during the coating process is essential for formation of a well-defined structure. This spraying process may also be used to spray materials that are not miscible with the base metal and/or that form brittle, intermetallic compounds.

[0013] According to one embodiment, plasma spraying within a vacuum is used as the spraying process. With plasma spraying in a vacuum, gas plasma is used as the heat source for heating and accelerating the material to be used. Spraying within a vacuum prevents the formation of oxide streaks as a result of the oxidation of the sprayed material during the coating process, and positively affects the structural formation.

[0014] Preferably, however, an RSPD (rapid solidification processing deposition, in which alloys are deposited on a carrier via atomization from the molten bath, with extremely rapid hardening) process can be used as the spray process for producing a coating or a component.

[0015] Alternatively, a high-speed powder or plasma spray process may be used as the spraying process. With high-speed powder spraying, combustion of a fuel gas-oxygen mixture takes place in a combustion chamber. The pressure that builds up within the chamber results in high particle speeds in a connected expansion nozzle. Both methods result in improved adhesion and coating density.

[0016] In accordance with another embodiment, a cold-kinetic compaction process can be used as the spraying method.

[0017] In order to ensure a high resistance to corrosion, a nickel-titanium alloy—as described in German publication DE 197 41 019—is used. This alloy is formed into a component in accordance with the method described above, or is applied to a component as a coating. The disclosure of German publication DE 197 41 019 also applies in connection with this application.

[0018] The temperature during the spraying process preferably is between 1000° C. and 1,000° C.

[0019] According to one embodiment of the invention, the vibration-damping alloy is applied to a component as a coating. The advantage of this is that the material can be applied via the method indicated in the form of a coating of any desired thickness. With the process specified in the invention, components and semi-finished products can be produced, and components and machinery elements can also be coated in a simple manner. The vibration damping achieved via the application of a coating can be established locally at specific points on a component. In this way, high stability and rigidity of the component can be combined with good damping properties. For example, components, especially engine components and machine tool components, which are supplied with a vibration-damping coating in accordance with the invention, exhibit significantly improved vibration behavior, and thus improved operating results.

[0020] In contrast to current damping elements made of rubber or plastics, higher thermal stress on the coated components and machinery elements is possible. In addition, the coating and the component exhibit high bond strength.

[0021] Basically, coatings of any thickness and any geometry can be produced. Preferably, the vibration-damping alloy is applied to the component as a coating measuring 0.1 to 25 mm in thickness.

[0022] In order to increase the bond strength between the coating and the component, the surface of the component to be coated is prepared prior to coating, for example via an abrading process, such as an irradiation process, e.g. laser or arc exposure, or plasma etching.

[0023] Preferably, following the application of the coating, a diffusion-heat process is conducted in order to increase the adhesion of the coating to the component.

[0024] After the coating process, the layer applied to the component possesses vibration-damping properties.

[0025] To produce components, especially machinery elements, experiments were conducted using titanium and steel sheets, which were coated with a nickel-titanium shape-memory alloy. This coating was applied, via plasma spraying in a vacuum, to a thickness of up to 0.5 mm. To produce a connection to the material of the component that is metallurgically free from defects, the test samples were heated prior to coating and cleaned using an arc.

[0026] A metallographic evaluation shows a dense coating with a very secure connection to the carrier material that is metallurgically free from defects, with a porosity of <1%.

[0027] The damping properties were verified in the first stage using an acoustic sampling and attenuation measurements.

[0028] With the method specified, both semi-finished products and components can be produced from, and thus coated with, a vibration-damping alloy, e.g., a shape-memory alloy, or a vibration-damping intermetallic compound. A further application of the process specified in the invention involves components from the field of engines, such as housings, disks, and blades that are vibration-damped with a coating and thus are placed under reduced stress, resulting in a longer lifespan.

[0029] Application of the coating via the process specified to machinery elements for the purpose of passive vibration damping is especially advantageous for cutting machine tools, as it allows significantly improved processing results in the surface quality achieved, along with higher processing speeds with materials that are difficult to machine.

[0030] Further, any case in which the coatings are applied to machinery elements for the purpose of vibration damping, in accordance with the above-described process, is advantageous when a high degree of bond strength and high thermal and corrosion resistance are required.

[0031] The invention will be described below in greater detail with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG. 1 is a perspective view of a fixed blade segment of a gas turbine, and

[0033] FIG. 2 shows a tool-receiving socket with a tool.

DETAILED DESCRIPTION OF THE DRAWINGS

[0034] FIG. 1 shows a fixed blade segment 1 of a gas turbine that has been coated in accordance with the invention. The four fixed blades of the segment 1 that are bombarded by the operating gas are provided at least over a majority of their surfaces with a vibration-damping coating 2 comprised of a suitable alloy or intermetallic compound.

[0035] FIG. 2 shows a component in the form of a tool-receiving socket 3 for a milling cutter 4 or some comparable tool, wherein the tool-receiving socket 3 as a whole is made of a vibration-damping alloy or a vibration-damping, intermetallic compound.

[0036] The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.

Claims

1. A method for producing at least one of a compound and a coating comprised of a vibration-damping alloy or intermetallic compound, comprising producing the at least one of the compound and the coating via thermal spraying.

2. The method according to claim 1, wherein the thermal spraying is plasma spraying in a vacuum.

3. The method according to claim 1, wherein the thermal spraying is performed by rapid solidification processing deposition.

4. The method according to claim 1, wherein the thermal spraying is high-speed powder or plasma spraying.

5. The method according to claim 1, wherein the thermal spraying is a cold-kinetic compaction process.

6. The method according to claim 1, wherein the vibration-damping alloy is a nickel-titanium alloy.

7. The method according to claim 1, wherein a temperature during the thermal spraying is between 100° C. and 1,000° C.

8. The method according to claim 1, wherein the vibration-damping alloy is applied to a component as a coating having a thickness of 0.1 to 25 mm.

9. The method according to claim 1, wherein a surface of a component to be coated is prepared prior to application of the coating in order to increase bond strength between the coating and the component.

10. The method according to claim 9, wherein the surface is prepared via an abrading process.

11. The method according to claim 1, and further comprising subjecting the coating to thermal treatment following application of the coating to a component.

12. The method according to claim 10, wherein the abrading process is an irradiation process.

13. The method according to claim 12, wherein the irradiation process is performed by laser or arc exposure.

14. The method according to claim 9, wherein the surface is prepared via plasma etching.

15. A component produced in accordance with the method of any of claims 1-14.