WO2004007787A1 - Layered system - Google Patents

Abstract

Layered systems in prior art often exhibit poor adhesion between the various layers. This causes the layers to separate and the underlying substrate is damaged. An inventive layered system (1) comprises a thermal insulation layer (10), at least sections of which contain material of the intermediate layer (7) lying below.

Description

S hich system

Field of the Invention

The invention relates to a layer system according to the preamble of claim 1.

In today's modern power generation plants, e.g. Gas turbine plants, the efficiency plays an important role because this reduces the costs for operating the gas turbine plant. One way to increase efficiency and thus reduce operating costs is to increase the inlet temperatures of a combustion gas within a gas turbine.

For this reason, ceramic thermal barrier coatings have been developed that are applied to thermally stressed components, for example made of superalloys, that cannot withstand the high inlet temperatures in the long run.

The ceramic thermal barrier coating offers the advantage of a high temperature / corrosion resistance due to its ceramic properties, and the metallic substrate offers the advantage of the good mechanical properties in this composite or layer system.

Typically, an adhesion promoting or corrosion protective layer of the composition MCrAlY as the main component is applied between the substrate and the ceramic thermal barrier layer, where M means that a metal from the group

Nickel, chrome or iron is used.

The composition of these MCrAlY layers can vary.

It often happens that the thermal barrier coating on the corrosion protection layer or MCrAlY layer does not adhere well and / or flake off during application or during operation need to be re-injected by operating personnel not melting.

It is therefore an object of the invention to overcome this problem.

The object is achieved by a layer system according to claim 1.

Further advantageous refinements of the layer system are listed in the subclaims.

Exemplary embodiments of the layer system according to the invention are shown in the figures.

Show it:

1 shows a first layer system according to the invention, FIG. 2 shows a second layer system according to the invention with a concentration gradient, FIG. 3 shows a further layer system according to the invention and

Figure 4 shows an application example for a layer system according to the invention.

FIG. 1 shows a layer system 1 according to the invention. The layer system 1 has a substrate 4. The substrate 4 is, for example, a nickel or cobalt-based superalloy.

At least one intermediate layer 7 is present on the substrate 4, which serves as a corrosion, oxidation or adhesion-promoting layer and consists of an intermediate layer material. A single intermediate layer 7 is used here. This is, for example, a so-called MCrAlY layer, where M is an element from the group iron, cobalt or nickel. A thermal insulation layer 10 is applied to the outermost interface of the intermediate layer 7. The thermal barrier coating 10 is, for example, ceramic and consists, for example, of partially or fully stabilized zirconium oxide with up to 8% yttrium oxide or other rare earth oxides. The thermal insulation layer 10 contains a total of 5-60 vol% of the material of the intermediate layer 7, which ensures good adhesion of the thermal insulation layer 10 to the intermediate layer 7. The heat insulation layer 10 begins at the interface at which the material of the heat insulation layer 10 forms the matrix.

The layers 7, 10 can be applied by various types of plasma spraying, in particular by atmospheric plasma spraying (APS), or by cold gas spraying. In cold gas spraying, the particles of the material of the layers 7, 10 to be applied, like the substrate 4, have a low temperature during manufacture, i.e. they do not form plasma.

In order to achieve welding or anchoring of the particles to one another, the applied particles are applied to the substrate 4 at high speeds of up to 1000 m / s, as a result of which they bond to one another. In order to achieve a weld, the addition of a metallic component is necessary. This green body layer produced in this way can also be sintered or heat-treated in order to enable improved resistance to external mechanical stress.

Other ceramic materials can also be used instead of zirconium oxide.

FIG. 2 shows a further layer system 1 according to the invention, in which the concentration of the intermediate layer material 7 in the thermal insulation layer 10 decreases continuously, for example, starting from an interface 8 between the intermediate layer 7 and the thermal insulation layer 10 up to an outer surface 11 of the thermal insulation layer 10. In an area 12 half of the outer surface 11 within a certain layer thickness, the proportion of the intermediate layer material 7 can also be constant at 0 vol%.

The heat insulation layer 10 begins at the interface at which the material of the heat insulation layer 10 forms the matrix.

The gradient of the material composition in the thermal insulation layer can be created in various ways. During plasma spraying, an initial mixture of the different materials of the layers 7, 10 continuously and more or more material of the thermal insulation layer 10 and / or continuously or discontinuously less material of the intermediate layer 7 is added to the plasma jet, which directs the particles onto the substrate 4 added. It is also possible to use two burners, ie two separate plasma jets or one plasma jet and one cold gas jet for the two different materials.

FIG. 3 shows a further exemplary embodiment of a layer system 1 according to the invention.

The layer system 1 according to the invention is constructed, for example, according to FIG. 1 or 2, a first partial layer 13 of the thermal insulation layer 10 being applied by cold gas spraying. A second partial layer 16 of the thermal insulation layer 10 of the same material or with a different composition is applied to this cold gas-sprayed partial layer 13 of the thermal insulation layer 10 by means of atmospheric plasma spraying or by means of other types of plasma spraying (in a vacuum, ..).

It is also possible, for example, if the concentration of the metallic material in the thermal insulation layer 10 is to decrease towards the outside, during the application with the increasing coating time, to continuously increase the temperature of the particle beam until, for example, a plasma is generated. The arrangement of intermediate layer material 7 in the thermal insulation layer 10 aligns the expansion coefficients of the layers 7, 10 with one another, so that there is little or no thermal stress between the layers 7, 10 when heated, which prevents chipping.

This applies in particular if there is a graded or continuous transition of the layers 7, 10. In particular, porous layers 7, 10 are also produced in order to achieve an elongation tolerance because one

Porosity from 5 vol% can influence the expansion coefficient and the E-module.

FIG. 4 shows a rotor blade in a perspective view as an example of a layer system 1, which extends along a longitudinal axis 19.

The rotor blade 1 has, in succession along the longitudinal axis 19, a fastening area 22, an adjoining blade platform 25 and an airfoil area 28.

In the fastening area 9, a blade root 31 is formed, which serves to fasten the rotor blade 1 to a shaft of a turbomachine, also not shown. The turbine blade 1 with its blade area 28 is exposed to high temperatures within a gas turbine and is therefore protected against oxidation and heat by a layer system 1 according to the invention.

Claims

Patent claims 1. Schi cht sy s t em, in particular turbine blade, which has a substrate, at least one intermediate layer lying thereon made of an intermediate layer material and an outer thermal insulation layer, the intermediate layer material being partially present in the thermal insulation layer, d a d u r c h g e k e n n z e i c h n e t that at least one layer (7, 10) has been applied by cold gas spraying. 2. Layer system according to claim 1, so that the intermediate layer (7) is an anti-corrosion layer. 3. Layer system according to claim 1, d a d u r c h g e k e n n z e i c h n e t that the thermal insulation layer (10) is made of ceramic. 4. Layer system according to claim 1 or 2, so that the corrosion protection layer (7) has a layer of the composition MCrAlY, where M stands for an element from the group iron, cobalt or nickel. 5. Layer system according to claim 1 or 3, characterized in that the thermal barrier coating (10) has zirconium oxide as the matrix material. 6. Scilichtsystem according to one or more of the ^~ orher! Gene claims, characterized in that at least one layer (7, 10) has been applied by cold gas spraying. 7. Layer system according to claim 1, 3 or 5, so that the thermal insulation layer (10) has been applied at least partially by atmospheric plasma spraying. 8. Layer system according to claim 1, so that the concentration of the material of the intermediate layer (7) in the thermal insulation layer (10) decreases continuously. 9. Layer system according to claim 1, so that the intermediate layer material (7) is at least partially metallic. 10. Layer system according to one of the claims 1 - 9, d a d u r c h g e k e n n z e i c h n e t that the proportion of the intermediate layer material (7) present in the thermal insulation layer (10) is in the range of 5-60 vol%. 11. Layer system according to one of claims 1-9, d a d u r c h g e k e n n z e i c h n e t that the thermal insulation layer (10) or the at least one Intermediate layer (7) have a porosity of more than 5 vol%.