EP2122009A1

EP2122009A1 - Device for the protection of components having a flammable titanium alloy from titanium fire, and method for the production thereof

Info

Publication number: EP2122009A1
Application number: EP08706819A
Authority: EP
Inventors: Thomas Uihlein; Wolfgang Eichmann; Falko Heutling; Markus Uecker
Original assignee: MTU Aero Engines GmbH
Current assignee: MTU Aero Engines AG
Priority date: 2007-02-06
Filing date: 2008-01-29
Publication date: 2009-11-25
Also published as: WO2008095463A1; US20100143108A1; CA2675107A1; DE102007005755A1

Abstract

The present invention enables the use of titanium-based materials in gas turbine construction, especially in engine, and particularly in compressor, construction, in that a device is provided, which protects the components (guide vanes, guide vane steps, rotating vanes, rotating vane steps) stressed by the titanium fire and/or FOD by means of a layer system comprising at least two layers, wherein the system is located on the surface of the components to be protected and is firmly connected thereto, optionally with the aid of an adhesive layer. The outer layer is of ceramic, and the layer beneath the same is metal. Optionally, further layers may follow, wherein ceramic and metal layers alternate each other. The invention further provides a method for the production of the device according to the invention. By means of the at least partial use of titanium alloys, particularly for the guide vanes of gas turbines, the invention enables a significant weight reduction of compressors in that the nickel or steel-based materials utilized according to state of the art can be omitted in favor of lighter titanium alloys.

Description

Device for the protection of components with combustible titanium alloy from titanium fire and process for their production

The present invention is in the field of gas turbine technology, such as the power or power plant technology, settled, and in particular concerns occurring components. The invention proposes a device for protecting combustible titanium alloys from titanium fire and / or damage by foreign objects.

In order to optimize the efficiency of a gas turbine, which includes engines or, for example, power plant turbines, the mass should be as small as possible, in particular the rotating, in mobile units and the static (non-rotating) elements in order to change the rotational speed or the overall speed engine to cause the least possible changes in kinetic energy. In particular, in aircraft engines, a lower engine weight is desirable for the same performance, as this results in e.g. Fuel costs can be saved or a higher payload is enabled.

Due to the weight saving in modern compressors more and more often found lightweight construction leads to an increased use of components made of titanium alloys. In order to achieve the desired high outputs and efficiencies, the operating pressures and temperatures must be further increased. From a certain temperature and pressure level, however, a so-called Titan fire can arise. Since titanium burns very easily due to its high affinity to oxygen, such a fire is then no longer extinguishable and can within a short time - 8 to 10 seconds - and at temperatures up to 2500 ° C to major damage to the components, in extreme cases even to Total loss of the engine, drove. Possible causes of a titanium fire may include damage to blades, severe rubbing of the turbine blades on the housing, or even bearing damage.

In order to significantly reduce the possibility of a titanium fire - usually caused when blade tips rub against the housing - in the simplest case flammable (titanium-containing) mass can be removed from the critical area and replaced by steel or nickel alloys.

To protect the usually very highly stressed components and to increase the achievable precision coatings are often used in the art. For example, in an engine, these coatings typically include anti-wear, anti-corrosion, hot gas corrosion and oxidation, titanium fire, and layers to minimize the rotor-stator gap, as well as thermal insulation layers. In the area of the compressor layers are mainly used for protection against titanium fire and erosion protection.

In particular, in the area of the housing wall, this can be coated with several millimeters thick layers. These layers may include, for example, plasma sprayed oxide ceramic layers.

To minimize the damage caused by erosion, either very hard carbide layers in a metal matrix such as tungsten carbide cobalt or chromium carbide in nickel-chromium matrix are used, or the protection is due to the ability of the protective layer, the kinetic energy of the erosive particles mitigate by plastic deformation, as is possible for example by appropriate coatings.

The blades, in particular the guide vanes of the particularly heat-stressed high-pressure compressor themselves, are usually made of so-called "superalloys." Super alloys are high-alloy materials of complex composition (iron, nickel, platinum, chromium or cobalt-based with additions of the elements Co, Ni, Fe, Cr, Mo, W, Re, Ru, Ta, Nb, Al, Ti, Mn, Zr, C and B) for high-temperature applications. but in comparison with titanium, which is still used in forged form at least in low-pressure compressors, the density is approximately twice as high and therefore correspondingly heavy. Another way to use titanium in high-stress parts of the engine is to alloy it with aluminum (TiAl). This option is used primarily in the manufacture of the blades.

US Pat. No. 5,114,797 (Uihlein et al.) Proposes a three-layer coating for protection against titanium fire, which comprises a metallic adhesion-promoting layer, a heat-insulating intermediate layer of an oxidic nature, and a titanium-fire-retardant metallic coating. In particular, a nickel-aluminum alloy is proposed as the metallic adhesion-promoting layer, a zirconium oxide layer as the intermediate layer, and aluminum and / or aluminum oxide as the protective coating.

US 5,006,419 (Grunke et al.) Also proposes aluminum as a protective layer for the structural components. The protective mechanism is achieved here by the evaporation of aluminum.

US Pat. No. 5,114,797 cited from the prior art uses exactly three layers, the bonding layer being mandatory. A particularly wear or corrosion inhibiting effect of the coating is not known.

The aluminum coating proposed in US Pat. No. 5,006,419 is also locally removed, in particular in the case of locally acting thermal stresses, resulting in the possibility of premature damage (recrystallization, ignition) of the base material.

Due to the high strength and the low specific gravity of titanium, it is desirable to use the material titanium as extensively as possible in the production of movable and fixed elements of gas turbines, especially in the area of the compressor, and especially in the area of the guide vanes. It would be particularly good, if care is taken to ensure that the material neither through so-called erosion and / or FODs (Foreign Object Damage, damage by foreign objects), nor by so-called Titanium fire, which occurs, for example, as a result of rubbing on moving parts that are stationary and made of titanium, can be damaged or best protected.

It is therefore the object of the present invention to provide a device for the protection of components with combustible titanium alloy from titanium fire and / or from damage by foreign objects available, which is simple and inexpensive but still reproducible and process reliable to produce.

This object is achieved by a device according to claim 1 or in accordance with claim 2 or according to claim 3. A erfmdungsgemäßes system is the subject of claim 11. A erfmdungsgemäßes method is the subject of claim 12. Advantageous developments of the invention are set forth in the dependent claims.

In the design according to claim 1, the outer layer of the layer system or the ceramic layer is preferably a titanium-free or Niedrigtitanlialtiges multicomponent system. It is particularly preferred that the underlying layer consists of a titanium-free or low titanium-containing metallic layer.

The device according to the invention serves to protect highly stressed components, in particular turbine components such as guide vanes or moving blades, from external influences, in particular from titanium fire and damage by foreign objects, by means of a layer system comprising at least two layers firmly connected to the component.

The layer system is preferably high-melting and / or non-combustible. In a particularly advantageous design, the layer system is also erosion-inhibiting, in particular as a supplement.

A significant advantage of the invention lies in the fact that it makes it possible to use lighter, titanium-based materials in the area of highly stressed components, in particular in the field of gas turbine construction, and above all in the area of the guide vanes of the compressor. This results in a significant reduction in the weight of compressors. Due to the combination of metallic and ceramic layers provided in a preferred design, an expansion-adapted adaptation of the ceramic layers to the metallic base material is achieved. Furthermore, the metallic layers prevent propagation of cracks possibly occurring in the ceramic layers. The ceramic layers in turn protect the entire system from damage caused by excessive temperatures. Also, these layers provide protection against metallic contact of the base material in FODs.

By using a plurality of successive combinations of a respective ceramic and a metallic layer, the possible removal volume that can be damaged in the event of damage can be further increased.

Even with complete, local removal of the protective layer, the remaining coated surfaces hinder propagation of heat-induced ignition or burn-up of titanium-based base material, i. a so-called titan fire.

Since the coating can be very thin, it does not or only insignificantly influences the weight, the aerodynamics and the vibration resistance of the components protected by it.

The invention relates to a device for protecting combustible titanium alloys from titanium fire and / or damage caused by foreign objects (FODs). This is achieved by providing, in accordance with the invention, a protective layer system which encloses the entire component or parts thereof and which consists of at least two layers. In this case, the component may be a guide or moving blade of an axial turbomachine, for example a guide or moving blade of a compressor stage.

The most important properties of these layers are their lack of flammability and their high or very high melting point. In addition there is an erosion-inhibiting effect of at least the outermost layer of the layer system according to the invention. This outermost layer advantageously consists of a ceramic layer, in particular of a non-titanium-based multicomponent system. Particularly preferred embodiments of the ceramic layer are a chromium nitride layer or an aluminum nitride layer, a chromium-aluminum nitride layer. The layer following and concealing the ceramic layer consists in particular of a metallic layer, in particular of a non-titanium-based metal or metal alloy layer. Particularly preferred embodiments of the metallic layer are, for example, a chromium or nickel or alumium layer, or alloys thereof.

These two layers form in their common combination the simplest execution of the device according to the invention, hereinafter referred to as "basic composite".

In a further advantageous embodiment of the invention, the layer system comprises a sequence of at least two base groups. A significant advantage of such a structure is the provision of an increased abrasive mass, resulting in increased security against burn-through or breakdown of the layer system.

In a further embodiment of the invention, an adhesion-promoting layer is additionally present between the protective layer system and the base material.

In a further preferred embodiment, instead of an abrupt transition between some or all the layers of the layer system, a graded transition may be provided, for example in the form CrAl - (CrAl) N ₁ -x-CrAlN.

In a particularly preferred embodiment of the device according to the invention, in particular, the ceramic layer (s) is or are dimensioned such that they hinder the on and melting of the underlying titanium alloy of the base material for the duration of at least one titanium fire.

In a further, particularly preferred embodiment of the device according to the invention, the layer thicknesses of the layers are dimensioned so that the total thickness of the layer system does not exceed some, in particular three, millimeters, and in a particularly preferred embodiment is less than one millimeter, particularly preferably less than 3 / 10 mm, more preferably less than 2/10 mm, more preferably less than 1/10 millimeter. All versions of the layer system can cover either a component in its entirety or only parts of a component. Combinations of different designs, for example those of a basic composite with those of several base composites, with or without an adhesion-promoting layer, are likewise possible. If an entire assembly is in an area that requires protection from titanium fire and / or FODs, then all parts of the assembly, some parts, only a part, or only areas of a part can be protected with the device according to the invention. Any combination of protected parts or part areas is possible. If, for example, the assembly is a compressor, then either the guide vanes, the individual guide blade stages, the rotor blades, or the individual rotor blade stages and / or areas thereof can be protected by the device according to the invention.

All described embodiments have in common that the aerodynamics and the fatigue strength of the protected by means of the device according to the invention components is not or only slightly affected.

In a particularly preferred embodiment of the device according to the invention, this offers the possibility of being able to be renewed in case of repair.

Furthermore, a corresponding method for applying a layer system according to the invention to the surfaces to be protected is proposed according to the invention. It can be provided, for example, that the layer system by means of thermal spraying and / or by means of flame spraying and / or by means of vacuum plasma spraying and / or by means of EB-PVD (Electron Beam Physical Vapor Deposition, and / or by means of an electrochemical process and / or by sputtering and / or by vapor deposition (PVD) and / or by PVD (Physical Vapor Deposition) and / or by arc vapor deposition (CARC) is applied.

Further measures improving the invention will be described in more detail below together with the description of preferred embodiments of the invention with reference to the figures.

Show it: Figure 1 shows a structure of a layer system 1, which is composed of a ceramic outer layer Ia and an underlying metallic connection layer Ib ("basic composite"), which is located on a base material 2;

Figure 2 shows a structure of a layer system 1 of FIG. 1, which additionally a

Adhesive layer 3, which is located between the inner layer of the layer system of Figure 1 and the base material 2;

FIG. 3 shows a structure of a layer system 1 according to FIG. 1, which is composed of a plurality of mutually alternating ceramic layers Ia and metallic layers Ib (two basic composites); and

4 shows a layer system according to FIG. 3, which has been damaged by the impact of foreign objects or by contact with liquid titanium on the outer layers and has cracks 4 and 5, but the innermost layer is undamaged and thus the base material is protected.

Figure 1 shows the cross section through a layer system 1, which is composed of an outer ceramic layer Ia and an underlying metallic layer Ib. This composite, which is referred to below as the "basic composite", is in turn applied to and firmly bonded to a base material 2, of which only the near-surface part is shown, The base composite has the task of preventing the base material 2 from external influences, in particular from To protect high temperatures and FODs, as well as a risk of titanium fire to prevent or at least obstruct this, if titanium or a titanium alloy is used as base material 2.

This is achieved by virtue of the fact that the outer ceramic layer 1a has poor heat conduction and an extremely high melting point. It therefore keeps the heat from the underlying metallic layer Ib and prevents melting or melting of the same or of the base material 2 at least for the duration of a titanium fire. Furthermore it offers a particularly good erosion resistance. Finally, it prevents a first metallic contact with the base material 2 when metallic FODs occur.

Since the ceramic layer Ia may have a significantly different expansion coefficient from the base material 2, it is not directly on the base material 2, from where it could easily flake off, but it is by the metallic layer Ib, with which it is firmly connected, and which functions inter alia as a temperature expansion compensation layer held.

Since both layers Ia and Ib are non-flammable and high-melting according to the invention, they can not ignite and burn and / or melt at normal or elevated operating temperatures.

According to the invention, the thickness and composition of the layers can be dimensioned such that the layer composite offers effective protection against titanium fire and FODs, while at the same time not having a negative effect on the vibration resistance of the protected component.

Figure 2 shows an inventive layer system 1 of FIG. 1 consisting of a ceramic layer Ia and a metallic layer Ib, which is additionally underlaid with an adhesive layer 3 and firmly connected thereto. The adhesion-promoting layer 3 has the task of improving the adhesion between the metallic layer 1b and the base material 2 if the metallic layer 1b otherwise does not adhere sufficiently firmly to the base material 2.

FIG. 3 shows a layer system 1 according to the invention, which is constructed from two base composites from FIG. It therefore consists of an outer ceramic layer Ia, followed by a metallic layer Ib, another ceramic layer Ia, and finally a last metallic layer Ib. All layers are according to the invention firmly together and connected to the base material 2. Such a multi-layer construction increases the protective effect by providing a correspondingly higher volume, which can be removed in case of damage or titanium fire. FIG. 4 shows a layer system according to FIG. 3 and discloses a further object of the metallic layers 1b. In addition to the above-mentioned functions, it has the task of preventing the propagation of cracks 4 and 5, which occur, for example, as a result of the thermal shock-like stress when titanium fire occurs during contact with liquid titanium melt. Other causes of such cracks may be, for example, the vibration load of the components, or the occurrence of FODs on the components.

Even in the case of a complete local abrasion of the layer system 1, not shown in FIG. 4, the still intact areas of the layer system 1 obstruct or hinder the propagation of a titanium fire.

The present invention is not limited in its execution to the above-mentioned preferred embodiment. Rather, a number of variants is conceivable, which makes use of the illustrated solution even with fundamentally different types of use.

Claims

1. A device for the protection of components with combustible titanium alloy from titanium fire and / or damage by foreign objects, in particular for the protection of blades of a turbomachine, characterized in that the device for protecting the components comprises at least two layers exhibiting layer system and the outer layer of the layer system consists of a ceramic layer and the underlying layer of a metallic layer.

2. Device for protecting components with combustible titanium alloy from titanium fire and / or damage by foreign objects, in particular for protecting blades of a turbomachine, characterized in that the device for protecting the components layer system having at least one layer, wherein the layer of this layer system or the outer layer of this layer system comprises ceramic and metal and is formed as a graded layer, in such a way that in this (outer) layer, the proportion of ceramic increases from the inside to the outside and the proportion of metal decreases from the inside to the outside.

3. A device for the protection of components with combustible titanium alloy from titanium fire and / or damage by foreign objects, in particular for the protection of blades of a turbomachine, in particular according to one of claims 1 and 2, characterized in that the components are protected with a layer system having at least two layers , wherein the layer system is high-melting, non-combustible and erosion-inhibiting.

4. Device according to one of claims 1 and 3, characterized in that in a layer system comprising more than two layers in each case a ceramic alternates with a respective metallic layer.

5. Device according to one of the preceding claims, characterized in that there is additionally an adhesion-promoting layer between the innermost layer of the layer system and the base material.

6. Device according to claim 1 or one of claims 3 to 5, characterized in that the transition between some or all layers is graded.

7. Device according to one of the preceding claims, characterized in that the ceramic layer or the ceramic layers hindered or hinder the on and melting of the underlying titanium alloys for the duration of at least one titanium fire.

8. Device according to one of the preceding claims, characterized in that the

Layer system has a maximum thickness which is smaller than 0.1 mm.

A device according to any one of the preceding claims, characterized in that the layer system is located on some or all of the components or areas thereof comprising the group of vanes, the individual vane stages, the blades, or the individual blade stages of a compressor.

10. Device according to one of the preceding claims, characterized in that the

Layer system does not affect the fatigue strength of the primitive, and that the layer system is renewable in case of repair.

11. A system comprising at least one titanium or titanium alloy or titanium component, in particular a compressor blade or vane of a gas turbine, and a device for protecting said at least one component from titanium fire and / or damage from foreign objects, characterized in that Device according to one of the preceding claims is formed, and the layer system, which is comprised by this device or is formed, is applied to this component, wherein the outer layer of the layer system consists of a ceramic layer.

12. A method for producing the device according to one of claims 0 to 10 or of

System according to claim 11, characterized in that the application of the layer system by means of a coating method, in particular by means of vapor deposition and / or sputtering, takes place.