EP2851455B1 - Method of electroplating wear-resistant coating - Google Patents

Description

BACKGROUND OF THE INVENTION FIELD OF THE INVENTION

The present invention relates to a galvanically produced wear protection coating and to a corresponding process for its production.

STATE OF THE ART

In turbomachines, such as stationary gas turbines or aircraft engines, certain components are exposed to high temperatures and aggressive media, which require appropriate protection of the components, for example by coatings. Accordingly, it is known to provide components in turbomachinery with various coatings serving different purposes, such as hot gas corrosion protection coatings, wear protection coatings, and the like.

Known high-temperature wear protection layers usually include hard materials that can withstand wear. Such high-temperature wear protection layers are applied according to the prior art by build-up welding or thermal spraying. However, by thermal spraying or build-up welding not all component areas of a component for the application of a corresponding high-temperature wear protection layer accessible and by locally different thermal stresses on the component during the thermal spraying or build-up welding can lead to undesirable inhomogeneities in the wear protection layers or the underlying base material.

From the documents EP 2 096 194 A2 . WO 82/00162 A1 . EP 1 408 197 A1 . DE 10 2006 016995 A1 and EP 0 484 115 A1 Various methods for the electrodeposition of a layer with embedded hard material particles are known.

In addition, be the documents US 2007/227299 A1 such as US2012 / 099971 A1 called.

DISCLOSURE OF THE INVENTION OBJECT OF THE INVENTION

It is therefore an object of the present invention to provide a method for producing a high-temperature wear protection layer, in particular for components of turbomachines, as well as corresponding wear protection layers, in which no inhomogeneous thermal stresses of the component to be coated are produced and in particular allows a coating of the component in hard to reach areas becomes. In addition, the corresponding method should enable a homogeneous wear protection coating with good adhesion to the component to be coated and be as simple and effective as possible.

TECHNICAL SOLUTION

This object is achieved by a method having the features of claim 1. Advantageous embodiments are the subject of the dependent claims.

The invention is based on the idea that a wear protection coating, which comprises hard material particles and / or lubricant particles, can be produced by a galvanic production method, wherein the hard material particles and lubricant particles can be dispersed in a corresponding electrolyte bath. The invention builds on the fact that it is already known to deposit hot gas corrosion layers galvanically, as for example in the documents EP 0 424 863 A1 . DE 38 15 976 A1 and the US 4,895,625 A is described. Accordingly, a wear protection coating is proposed with an MCrAl matrix in which M stands for Co and / or Ni, in which hard material particles and lubricant particles are embedded in the matrix.

The hard material particles and lubricant particles may be contained together in a proportion of 5% by volume to 40% by volume, in particular 10% by volume to 30% by volume, in the wear protection coating and the matrix of the wear protection coating may be 15% by weight to 50% by weight. %, in particular 20 wt.% to 40 wt.% Cobalt and / or 15 wt.% to 50 wt.%, in particular 20 wt.% to 40 wt.% Nickel, 10 wt.% to 30 wt.%, in particular 10 Wt.% To 25 wt.% Chromium and 1 wt.% To 10 wt.%, In particular 2 wt.% To 8 wt.% Aluminum. The data for the composition are to be understood in this case that the composition is of course always 100 wt.% Results, wherein the ingredients are to be selected within the specified ranges and possibly additional alloying ingredients must be added. Is for example in the matrix of wear protection coating provided both cobalt and nickel, the maximum values of the specified ranges, ie in each case 50 wt.%, Can not be realized, as further at least 10 wt.% Chromium and 1 wt.% Aluminum must be included. However, if, for example, only cobalt is contained in the matrix, then the cobalt content can be selected in the entire specified range, since in addition to the other specified constituents chromium and aluminum, additional alloying constituents may be present.

In order to achieve the respective constituents of the wear-resistant coating, the following components can be used in suitable concentrations or amounts in the process for producing a wear-resistant coating described below.

In order to produce the MCrAl matrix of the desired wear protection coating, according to the invention an electrolyte is provided which contains cobalt and / or nickel. In this electrolyte first particles are dispersed, wherein the first particles comprise hard material particles and Gleitstoffpartikel. In addition, second particles are dispersed in the electrolyte, the second particles comprising metal alloy particles in which the metal alloy comprises chromium and aluminum. The first particles serve to introduce the hard material particles and lubricant particles provided in the wear protection coating to be produced, while the second particles in the form of the metal alloy particles serve to form the MCrAl matrix together with the electrolytes containing cobalt and / or nickel.

A suitably prepared electrolyte, in which the first and second particles are dispersed, is used for the electrodeposition of a layer on a component to be coated. The electrodeposited layer thus comprises a matrix of cobalt and / or nickel corresponding to the composition of the electrolyte as well as embedded first and second particles.

The electrodeposited coating is subjected to a heat treatment in which the embedded metal alloy particles are dissolved and, together with the deposited matrix of cobalt and / or nickel, form a corresponding MCrAl matrix in which M is formed by cobalt and / or nickel.

The heat treatment may be carried out at a temperature of 950 ° C to 1200 ° C, in particular 1000 ° C to 1150 ° C for 2 to 20 hours, in particular between 5 and 15 hours.

The heat treatment is carried out under vacuum, wherein component and electrodeposited layer can be homogeneously exposed to the corresponding temperature together. Alternatively, a local heating of the electrodeposited layer by a surface heating can be made.

The cobalt and / or nickel-containing electrolyte for electrodeposition may include nickel sulfate and / or cobalt sulfate. Further, sodium chloride and / or boric acid may be present in the electrolyte.

The metal alloy of the metal alloy particles may be formed by CrAl, CrAlY, CrAlHf, CrAlYHf, CrAlTa, CrAlYTa, CrAlSi, MoCrSiAl, CrCoAl, CrNiAl, and alloys of chromium and aluminum containing at least one or more elements selected from yttrium, hafnium, tantalum, silicon , Molybdenum, nickel and cobalt.

The first and second particles, ie the hard material particles and lubricant particles, and the metal alloy particles may each be provided in the electrolyte in a proportion of 50 g / l to 300 g / l, preferably a total amount of particles in the range 300 g / l to 400 g / l should not be exceeded.

The first particles may have a maximum or average particle size of less than or equal to 10 .mu.m, in particular between 1 .mu.m and 5 .mu.m, while the second particles may have a maximum or average particle size of less than or equal to 15 .mu.m, in particular between 1 .mu.m and 5 .mu.m.

The first particles in the form of hard material particles and lubricant particles have a metallic shell, in particular a shell which comprises or is formed from nickel and / or cobalt, in order to improve the introduction of the hard material particles and lubricant particles in the dispersed electrolyte process.

The first particles may include lubricant particles in the form of solid lubricants, particularly in the form of hexagonal boron nitride, to reduce wear through improved sliding movement of the coating with the wear components.

The first particles in the form of hard material particles can be formed by oxides, in particular chromium oxide or zirconium oxide, which protect the underlying component by its hardness and thus resistance to the wear partners.

Overall, the invention provides the possibility of creating a wear protection coating which is suitable in particular for turbomachinery and has an MCrAl matrix with embedded hard material particles and lubricant particles, which can be applied uniformly to a component even in hard-to-reach places without undue, in particular inhomogeneous temperature loads.

BRIEF DESCRIPTION OF THE FIGURES

• Fig. 1 eine Querschnittansicht eines erfindungsgemäß dispergierten Elektrolytbades;
• Fig. 2 eine Querschnittansicht eines erfindungsgemäß dispergierten Elektrolytbades bei der galvanischen Abscheidung einer Schicht auf einem zu beschichtenden Bauteil;
• Fig. 3 einen Querschnitt durch ein Bauteil mit einer erfindungsgemäß abgeschiedenen Schicht; und in
• Fig. 4 einen Querschnitt durch ein Bauteil mit einer erfindungsgemäß abgeschiedenen Verschleißschutzbeschichtung nach einer
  Wärmebehandlung.

The accompanying drawings show in a purely schematic manner in FIG

• Fig. 1 a cross-sectional view of an inventively dispersed electrolyte bath;
• Fig. 2 a cross-sectional view of an inventively dispersed electrolyte bath in the electrodeposition of a layer on a component to be coated;
• Fig. 3 a cross section through a component with a deposited according to the invention layer; and in
• Fig. 4 a cross section through a component with a deposited according to the invention wear protection coating according to a
  Heat treatment.

Embodiment

Further advantages, characteristics and features of the present invention will become apparent in the following detailed description of an embodiment. However, the invention is not limited to this embodiment.

The Fig. 1 shows an electrolyte 3 in an electrolyte bath in which first particles 1 and second particles 2 are dispersed.

The electrolyte is a mixture of cobalt sulfate, nickel sulfate, boric acid and sodium chloride, for example 240 g / l cobalt sulphate, 240 g / l nickel sulphate, 35 g / l boric acid and 20 g / l sodium chloride. The ph value of the electrolyte is set between 4.5 and 4.7.

The first particles 1 dispersed in the electrolyte 3 are hard particles and lubricant particles. The hard material particles may be formed by oxides and in the present preferred embodiment, the hard material particles are formed by chromium oxide or zirconium oxide, which are added in the form of particles having average particle sizes of 5 microns in an amount of 100 g / l to the electrolyte. Moreover, the first particles are formed by lubricant particles formed by a solid lubricant such as hexagonal boron nitride. The lubricant particles are also dispersed in the electrolyte with an average particle size of 5 μm at a concentration of 100 g / l.

The second particles 2 contained in the electrolyte 3 are metal alloy particles containing at least chromium and aluminum, especially predominantly chromium and aluminum. In this case, predominantly means that the sum of the proportions of chromium and aluminum form the largest alloy constituent of the metal alloy particles, in particular make up more than 50% by weight of the metal alloy of the metal alloy particles.

The second particles 2 can also be dispersed in the electrolyte 3 with an average particle size of 5 microns in an amount of 200 g / l.

The electrolyte is brought to a temperature of 30 ° C to 70 ° C and kept in motion by suitable stirrers or the like, so that the dispersed first and second particles 1, 2 are uniformly distributed in the electrolyte 3.

The Fig. 2 shows the electrolyte bath Fig. 1 in a galvanic deposition of a wear protection coating according to the invention on a component 4. In this case, the component is connected as a cathode to a power supply 6, while an additional anode 5 is arranged in the electrolyte bath.

The Fig. 3 shows the component 4 with the deposited layer 7, which has a NiCo matrix with embedded first particles 1 and second particles 2. The current density in the electrodeposition may be in the range of 1 to 10 A / dm ² .

The deposited layer 7 is heat-treated together with the component 4 in a temperature range of 1000 to 1150 ° C. for 5 to 15 hours under vacuum, so that the second particles 2 are made of a CrAl alloy together with the CoNi matrix of the deposited ones Layer form a CoNiCrAl matrix in which hard material particles 9a of chromium and / or zirconium oxide and lubricant particles 9b of hexagonal boron nitride are present in the CoNiCrAl matrix in order to form the wear protection coating 10 on the component 4.

If, for example, a CrAlY alloy is used for the second particles 2, then a CoNiCrAlY matrix 8 of the wear protection coating 10 is formed.

In the embodiment shown the Fig. 1 to 4 For example, the first particles 1 are provided with a metal shell of nickel and / or cobalt, which are in the heat treatment step between 3 and 4 dissolves in the matrix 8, so that the hard material particles 9a and the Gleitstoffpartikel 9b are present without surrounding casing in the wear-resistant coating 10.

Although the present invention has been described in detail with reference to the embodiment, in particular with respect to the materials used and the process parameters, it is obvious to the person skilled in the art that the invention is not limited to these materials and process parameters or generally the information in the embodiment, but rather Variations are possible in the way that other materials can be used and different process parameters can be used without departing from the scope of the appended claims. In particular, it is possible to omit individual introduced features or to make other types of combinations of features without departing from the scope of the appended claims. The disclosure of the present application includes all combinations of the featured individual features.

Claims (10)

1. Method for producing a wear-resistant coating (10) on a component, in particular a component of a turbomachine, wherein the method comprises the following steps:

   - providing an electrolyte (3), which contains Co and/or Ni,

   - dispersing first particles (1) in the electrolyte, wherein the first particles comprise hard material particles and slip material particles and have a metal covering, in particular a covering that comprises Ni and/or Co or is formed therefrom,

   - dispersing second particles (2) in the electrolyte, wherein the second particles comprise metal alloy particles in which the metal alloy has chromium and aluminum,

   - putting the component (4) to be coated in a bath of the electrolyte in which first and second particles have been dispersed,

   - applying a matrix of Co and/or Ni comprising embedded metal alloy particles (2) and embedded hard material particles and slip material particles (1) to the component by electrodeposition, and

   - subjecting the component to heat treatment under vacuum.
2. Method according to claim 1, characterized in that the heat treatment is carried out at a temperature of from 950°C to 1200°C, in particular from 1000°C to 1150°C, for 2 to 20 hours, in particular for between 5 and 15 hours.
3. Method according to either claim 1 or claim 2, characterized in that the electrolyte (3) comprises NiSO₄ and/or CoSO₄.
4. Method according to any of the preceding claims, characterized in that the electrolyte (3) comprises NaCl and/or H₃BO₃.
5. Method according to any of the preceding claims, characterized in that the metal alloy of the metal alloy particles (2) has a composition selected from the group comprising CrAI, CrAlY, CrAlHf, CrAlYHf, CrAITa, CrAlYTa, CrAlSi, MoCrSiAl, CrCoAl, CrNiAl and alloys comprising Cr and Al which comprise one or more elements selected from Y, Hf, Ta, Si, Mo, Ni and Co.
6. Method according to any of the preceding claims, characterized in that the first and second particles (1, 2) are each provided in the electrolyte in a proportion of from 50 g/l to 300 g/l.
7. Method according to any of the preceding claims, characterized in that the first particles (1) have a maximum or average particle size of less than or equal to 10 µm, in particular of between 1 µm and 5 µm.
8. Method according to any of the preceding claims, characterized in that the second particles (2) have a maximum or average particle size of less than or equal to 15 µm, in particular of between 1 µm and 5 µm.
9. Method according to any of the preceding claims, characterized in that the slip material particles (1) comprise solid lubricants, in particular hexagonal boron nitride.
10. Method according to any of the preceding claims, characterized in that the hard material particles (1) comprise oxides, in particular chromium oxide or zirconium oxide.

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