WO2008031373A1

WO2008031373A1 - Method for coating machine components and method for producing a block from a coating material

Info

Publication number: WO2008031373A1
Application number: PCT/DE2006/001656
Authority: WO
Inventors: Rene Jabado; Jens Dahl Jensen; Ursus KRÜGER; Daniel Körtvelyessy; Ralph Reiche; Michael Rindler; Gabriele Winkler
Original assignee: Siemens Aktiengesellschaft
Priority date: 2006-09-15
Filing date: 2006-09-15
Publication date: 2008-03-20
Also published as: DE112006004133A5

Abstract

The invention relates to a method for coating machine components (10), especially compressor components, with a coating material (9). The coating material is provided in the form of a block (7) and is rubbed onto the surface (4) to be coated by means of said block (7). The coating material used is a material which comprises monomers that undergo a polycondensation reaction when heat-treated. Once the coating material is rubbed onto the surface, the machine component (10) is subjected to a heat treatment. The invention also relates to method for producing a block (7) from a coating material (9), comprising the steps of: mixing the components of the coating material with a binder which comprises monomers or is capable of forming them, said components undergoing a polycondensation reaction when heat-treated, forming the mixture to give a block (7), sintering the formed mixture.

Description

description

A method of coating machine components and methods of making a block of coating material

The present invention relates to a method for coating machine components with a coating material and to a method for producing a block of coating material.

To protect component surfaces, for example for the protection of compressor blade surfaces from corrosion and wear, they are provided with a corrosion-inhibiting and / or oxidation-inhibiting coating and optionally also with a thermal barrier coating (TBC). The coatings are applied by means of classical painting and spraying techniques. In this case, solid particles such as metal particles, ceramic particles, oxide particles, pigment particles, etc. with particle sizes in the micrometer and nanometer range (micro- and nanoparticles) are suspended or dispersed in a binder and then applied to the component surface by means of the mentioned coating and / or spraying techniques , Subsequently, the applied layer is subjected to a heat treatment to crosslink it. However, the painting and / or spraying techniques used lead to the formation of acidic aerosols, which makes elaborate safety measures, such as in the form of a closed spray booth, necessary when carrying out the painting and / or spraying techniques.

JP 09279057 A describes a method for repairing a coating. There, a scratch in a coating is repaired by passing a pencil over the scratch with a repair material, with material in the coating Scratches deposited. Excess material is then wiped off with a cloth and finally a resin is applied over the repair site.

The preparation of such pins can be done, for example, by compacting and sintering powder suspensions. The behavior of aluminum powder suspensions with three different average particle sizes in the nanometer range in compacting and sintering is described, for example, in the article by Jian-Lin Shi and J.D. Zhang, "Compaction and Sintering Behavior of Bimodal Alumina Powder Suspensions by Pressure Filtration", J. Am. Ceram. Soc., 83 (4), 737-42 (2000).

The object of the present invention is to provide an advantageous method for coating machine components using a block. It is a further object of the present invention to provide a method of making a block suitable for use in the process of coating engine components.

These objects are achieved by a method for coating machine components, in particular compressor components, according to claim 1 and a method for producing a block of coating material according to claim 8. The dependent claims contain advantageous embodiments of the invention.

In the method according to the invention for coating machine components, in particular for coating compressor components, such as compressor blades, with a coating material, the coating material is provided in the form of a block, for example as a pin. The coating material is applied to the coating material by means of the block. de surface rubbed. The coating material used is a material which has monomers which undergo a polycondensation reaction under the action of heat. After the coating material has been applied to a machine component, it is subjected to a heat treatment.

The method according to the invention makes it possible to produce a coating, in particular a corrosion and / or oxidation-inhibiting coating on machine components, with only one application step. In contrast, in the above-cited method, a second application step, namely the application of the liquid resin is necessary. At the beginning of the heating step, there is also a flow of the rubbed coating material, which compensates for unevenness arising during reaming. Wiping the surface after the application of the coating material is therefore not necessary in contrast to the prior art.

The method according to the invention also offers the advantages over painting and spraying methods for applying coatings which are resistant to corrosion and / or oxidation to machine components that no expensive securing measures, such as closed spray booths, are necessary. The reaming of the coating material is therefore economically more favorable. In addition, the rubbing offers the possibility of applying the coating on site, for example when repairing corrosion and / or wear protection layers. Removing and transporting the machine component to a coating plant is therefore not necessary.

In particular, on site, the heat treatment by means of heating elements, such as heating cables or heating mats, are performed. These become at least after application of the coating material to the machine component applied where the surface to be coated is located. Alternatively, the heating can also be done without contact by means of radiant heaters.

If the surface to be coated is the surface of a cracked coating, such as occurs in the case of reprocessing a worn and / or corroded coating, the block of coating material is preferably rubbed across the surface to be coated, transverse to the direction of expansion of the cracks. As a result, more material is deposited in the region of the rear crack edge in the direction of movement than elsewhere. In other words, where more coating material is needed (to fill the cracks) more material is deposited. In the heat treatment then the deposited material in the

Cracks flow, resulting in a substantially flat surface of the coating.

Advantageously, the coating material may comprise particle sizes in the micrometer range and particle sizes in the nanometer range. The use of at least two very different particle sizes allows for a stronger compaction of the applied coating. In this case, particle sizes are to be understood as meaning in each case the mean particle size, since the particles generally have a size distribution. A coating material which comprises particles having two particle sizes therefore has a particle size distribution with two pronounced maxima in the range of the respective average particle size. In the present case, therefore, at least a maximum in the nanometer range and at least a maximum in the micrometer range are present.

Advantageously, the heat treatment includes a temperature step at a temperature above 300 ⁰ C. Such a tem- can, for example in the case of diphosphoric acid as monomers, cause a polycondensation of the monomers.

The coating material used can be, in particular, a coating material having at least one color pigment. This makes it possible to give the coating material a different color than the material of the surface to be coated. On the one hand, this makes it possible to identify where coating material has already been wiped, and, on the other hand, it is possible to detect in the finished coating where coating material has been removed due to wear and / or corrosion down to the underlying substrate material.

The quality of the abraded coating is determined on the one hand by the bonding forces within the block and the roughness of the workpiece surface and on the other by the pressure and speed of the block against the surface during application. It is therefore of advantage if the block for reaming the coating is guided over the surface to be coated at a defined speed and / or pressure.

The method of making a block of coating material according to the invention comprises the steps of mixing the constituents of the coating material with a binder comprising monomers which undergo a polycondensation reaction under heat treatment, forming the mixture into a block and sintering the formed mixture.

A block of coating material produced by the method according to the invention can be used for carrying out the method according to the invention. The hardness of the Blocks can be adjusted by the type and amount of the binder added. Thus, for example, the strength of the block can be adapted to the roughness of the surfaces to be coated as well as the rubbing of the coating material as usual friction pressures and friction speeds.

As a suitable binder such as phosphoric acid and / or chromic acid may be used. The phosphoric acid can be converted into an annealing below 200 ⁰ C, which can be carried out, for example, as part of the sintering acid in diphosphoric. The diphosphonic acid is a monomer having a temperature above 300 ⁰ C undergoes Polykondensationsreak- tion in a later suitable heat treatment.

The mixture of the constituents of the coating material may also be admixed with at least one color pigment. The advantages of color pigments in the coating material have already been described with reference to the process for coating machine components.

Further features, properties and advantages of the present invention will become apparent from the following description of embodiments with reference to the accompanying figures.

Fig. 1 shows a highly schematic of a machine component with a cracked coating.

Fig. 2 shows the component of Fig. 1 when rubbed by the coating material. Fig. 3 shows the coated component after performing a heat treatment.

The method according to the invention for coating a machine component is described below with reference to FIGS. 1 to 3 in connection with the repair of a cracked corrosion-inhibiting coating on a compressor blade as an example of a machine component.

Fig. 1 shows a highly schematic representation of a section through the wall of a compressor blade 10. It can be seen the base material 1 of the wall and the existing on the wall corrosion-inhibiting coating 3. The coating 3 has cracks 5 due to an operational stress. The inventive method is in the present embodiment in the context of a reprocessing process for the compressor blade 10, ie in the context of a so-called refurbishment performed.

By means of a block in the form of a pin 7, which consists of pressed and sintered coating material, a layer 9 of fresh coating material is rubbed onto the old coating 3. Due to adhesion forces and frictional forces between the surface of the worn layer 3 and the pin 7, coating material 9 deposits from the pin 7 on the surface 4. The stroke of the pin 7 in this case takes place so that the cracks 5 are swept by the pin 7 transversely to its direction of extension. As a result, more material is applied to the cracks 5 than undamaged surface areas. The additional material

11 forms a material depot, which fills the cracks 5 in the further course of the process. The layer thickness and the layer quality of the material layer 9 are determined by the binding forces within the pin 7, the roughness of the surface 4 to be coated, the pressure exerted on the block 7 when rubbed, and the speed of the pin 7 relative to the surface 4 certainly. By a suitable choice of parameters, therefore, a variation of the thickness of the material layer 9 and its quality is possible.

The production of the pin 7 is carried out in the present embodiment by mixing the constituents of the coating material with a binder which comprises monomers undergoing a polycondensation reaction under heat treatment. In the present embodiment, phosphoric acid is used as a binder. However, other binders which comprise such monomers can also be used in principle. Alternatively or in addition to the phosphoric acid, chromic acid may be present. Other constituents of the coating material in the present exemplary embodiment are water, pulverulent chromium (III) compounds and (optionally) pulverulent pigments.

The pulverulent coating constituents, in particular at least the aluminum, have a particle size distribution which has at least two maxima with distinctly different particle sizes. In particular, a maximum in the case of particle sizes in the nanometer range, ie particle sizes below one micrometer, and preferably below 100 nanometers, whereas the second maximum is above one micrometer for particle sizes.

After mixing the solid and liquid components and the phosphoric acid, the mixture is poured into a mold and pressed into a pin. In addition, a sintering process at temperatures wherein the phosphoric acid that was present above as mono phosphoric acid (H ₃ PO _4), pyrophosphoric acid (H ₄ P ₂ O ₇₎ is converted up to 200 ⁰ C, but not above. The diphosphoric acid later serves as the basis for polycondensation. The hardness of the pencil to be produced can be adjusted by suitable choice of a binder. After pressing and sintering, the pin can be used for coating.

After the layer 9 of coating material has been applied to the surface 4 of the worn coating 3, an annealing takes place which has at least one temperature step above 300 ^° C. During annealing, the material from the material depots 11 fills the cracks. In addition takes place in the at least one annealing over 300 ⁰ C, the polycondensation of the diphosphoric acid, so that a network of Metapolyphosphorsäure (H _{n + 2} P _n O _{3n +} I) = (H ₃ PO ₃₎ _n forms.

The heat treatment may be carried out either by placing the entire compressor blade 10 in an oven, or by covering the blade with heating mats or by wrapping heating cables. Heating mats and heating cables are particularly suitable if the reprocessing on site and place, as the compressor, takes place. Instead of heating mats or heating cables but also devices for radiant heating, such as radiant heaters, can be used.

Since the application of the coating material by means of a pin no acidic aerosols, no expensive safety measures are necessary. The application of the coating material is thereby simpler and less expensive. In addition, the application can be done on site, which in particular simplifies the repair of corrosion and wear protection layers, for example, when cracking. By A special coloring of the applied coating material by adding color pigments to the pen can mark the coating.

Finally, it should be noted that although the layer 9 has been applied to an already existing worn coating in the exemplary embodiment described, the worn coating is not a prerequisite for carrying out the coating method according to the invention. Instead of being worn on a worn coating, the layer 9 can also be wiped directly onto the surface of the base material of the machine component.

Claims

claims

1. A method for coating machine components (10), in particular compressor components, with a coating material (9) in which the coating material is provided in the form of a block (7) in which the coating material (9) by means of the block (7 ) is rubbed onto the surface (4) to be coated, characterized in that a material is used as the coating material, which has monomers which undergo a polycondensation reaction under heat treatment and the machine component (10) is subjected to a heat treatment after the coating material has been applied.

2. The method according to claim 1, characterized in that after the application of the coating material (9) heating elements are applied to the machine component (10) at least where the surface to be coated (4) is located and the heat treatment by means of the heating elements is carried out.

3. The method according to claim 1, characterized in that the heating takes place by means of radiant heaters.

4. Method according to one of the preceding claims, in which the surface (4) to be coated is the surface of a crack (5) having coating (3) and the block (7) with coating material (9) transversely to the direction of extension of the cracks ( 5) is rubbed over the surface to be coated (4).

5. The method according to any one of the preceding claims, in which the coating material (9) with particle sizes in the micrometer range and particle sizes in the nanometer range comprises.

6. The method according to any one of claims 1 to 5, wherein the monomers comprise diphosphoric acid and the heat treatment comprises a temperature step having a temperature above 300 ⁰ C.

7. The method according to any one of the preceding claims, in which a coating material (9) is used with at least one color pigment.

8. The method according to any one of the preceding claims, in which the block (7) for reaming the coating material (9) with a defined speed and / or a defined pressure on the surface to be coated (4) is guided.

9. A method of manufacturing a block (7) of coating material (9), comprising the steps of:

Mixing the constituents of the coating material with a binder which has or can form monomers which, upon heat treatment, undergo a polycondensation reaction,

Forming the mixture into a block (7), sintering the shaped mixture.

10. The method according to claim 9, wherein the hardness of the block (7) is adjusted by the type and amount of the admixed binder.

11. The method according to claim 9 or 10, in which phosphoric acid and / or chromic acid is used or come as a binder.

12. The method of claim 11, wherein the phosphoric acid is converted by an annealing step in diphosphoric acid.

13. The method according to any one of claims 9 to 12, in which the mixture is admixed at least one color pigment.