Patent Application
20090269207
This application claims the priority of International Application No. PCT/DE2006/000379, filed Mar. 3, 2006, and German Patent Document No. 10 2005 011 011.8, filed Mar. 10, 2005, the disclosures of which are expressly incorporated by reference herein.
The invention relates to a component, specifically a component for a gas turbine.
Components for a gas turbine, such as the rotor blades, are given special wear protection coatings to provide oxidation resistance, corrosion resistance or erosion resistance. The components of gas turbines are subject to wear during operation or can be damaged in other ways. To repair damage it is usually necessary to remove or strip the wear protection coating from the component to be repaired in specific areas, partially or even completely. The removal or stripping of coatings is also called decoating. In the decoating processes a distinction is made between those in which the decoating is carried out by mechanical means, chemical means or electrochemical means.
With chemical or even electrochemical decoating of a component the risk exists that the basic material of the main body coated with the wear-protection coating will be attacked or removed. With some base materials, such as titanium alloys, this can result in a deterioration of the material properties. In the case of titanium alloys the HCF strength may be reduced. Consequently, in accordance with the prior art, expensive steps must be taken in the decoating of components to prevent the basic material of the main body from being attacked.
With this as the starting point, the problem underlying the present invention is to create a novel component, specifically a novel component for a gas turbine.
In accordance with the invention, a resistive layer is located between the main body and the wear protection coating to protect the main body during chemical or electrochemical decoating of the component.
Within the meaning of the present invention it is provided to locate a resistive layer between the main body and the wear protection coating for a coated component. The protection coating protects the main body of the component from attack from the decoating during chemical or electrochemical decoating. To this extent, there is no further risk during chemical or electrochemical decoating of such a component that the material properties of the base material are negatively affected. The protection coating is resistant to chemical and electrochemical decoating.
Preferably the barrier coating has a material composition matched to the material composition of the main body, where the material of the barrier coating is alloyed, or enriched with an element relative to the base material of the main body from the platinum group and/or with nickel and/or with molybdenum.
Preferred further developments of the invention emerge from the subsequent description. An embodiment of the invention, without being limited thereto, is described in more detail using the drawing.
Hereinafter the invention is described in greater detail with reference to
Within the meaning of the present invention, a barrier coat 16 is positioned between the wear protection coating 12 and the main body 11 of the component 10 in accordance with the invention. The barrier coat 16 is located between the main body 11 and the lowest, or innermost, layer 13 of the wear protection coating 12. The barrier coat 16 assumes the function of protecting the main body 11 during chemical or electrochemical decoating. The barrier coat 16 is therefore resistant to chemical or electrochemical decoating and is not attacked, or removed, during such a decoating so that the base material of the main body 11 is not attacked or removed.
The barrier coat 16 has a material composition which is matched to the material composition of the main body 11. Preferably both the main body 11 as well as the barrier coat 16 are made from a titanium-based alloy. The material of the barrier coat 16 is enriched or alloyed with at least one element from the platinum group and/or with nickel and/or molybdenum relative to the base material of the main body 11.
Thus the material of the barrier coat 16 may have platinum in a percentage of at least 0.05% by weight. Similarly, the material of the barrier coat 16 may have palladium in a percentage of at least 0.05% by weight. Similarly, the material of the barrier coat 16 may have nickel in a percentage of at least 0.50% by weight and/or molybdenum in a percentage of at least 4.00% by weight. One or even more of these elements may be present in the above specified proportions in the barrier coat 16.
As already mentioned, the barrier coat protects the base material of the main body against attack during chemical or electrochemical decoating of the component. This ensures that during decoating the material properties of the base material of the main body are not negatively affected. An additional advantage of the barrier coat is that it is relatively smooth. Thus, following decoating a newly applied wear protection coating is able to adhere better to the base body than would have been possible with decoating in the case of a main body attacked or etched during decoating from the state of the art. Since the barrier coat has a material composition matched to the material composition of the main body there are no matching problems for the wear protection coating.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2005 011 011.8 | Mar 2005 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/DE2006/000379 | 3/3/2006 | WO | 00 | 11/30/2007 |
