COATED ABRASIVE PARTICLES, COATING METHOD USING SAME, COATING SYSTEM AND SEALING SYSTEM

Abstract

A soldering method in which abrasive particles, in particular cubic boron nitride, are applied in a matrix composed of a solder material and are intended to have better adhesion in the matrix material. The particle which includes an abrasive particle, in particular of cubic boron nitride, is coated with a metal. A method for producing a layer on a substrate, wherein a solder material is applied as metallic matrix material such with particles, in particular solder material in the form of a soldering paste, a soldering tape, a solder powder, by an application method, in particular by a welding process or a thermal spraying process.

Claims

1. A particle, comprising: an abrasive particle, and a coating of metal on the abrasive particle.

2. The particle as claimed in claim 1, wherein the coating of metal comprises titanium (Ti) and/or nickel (Ni).

3. The particle as claimed in claim 2, wherein only one coating of metal is present around the abrasive particle.

4. A method for producing a layer, comprising: using particles as claimed in claim 1.

5. The method as claimed in claim 4, wherein the particles are or have been mixed with a metallic matrix material and are applied.

6. A method for producing a layer on a substrate, comprising: applying a solder material as metallic matrix material with particles as claimed in claim 1 by an application method, wherein the melting point of the solder material is at least 10 K lower than that of the substrate.

7. A layer system, comprising: a substrate comprising a layer, wherein the layer comprises a solder material and particles as claimed in claim 1, wherein the solder material has a melting point which is 10 K lower than that of the material of the substrate.

8. A sealing system, comprising: a stator and rotating parts comprising a layer system as claimed in claim 7.

9. The particle as claimed in claim 1, wherein the abrasive particle comprises cubic boron nitride.

10. The particle as claimed in claim 3, wherein only one metal is present around the abrasive particle.

11. The method as claimed in claim 6, wherein the solder material is in the form of a soldering paste, a soldering tape, and/or a solder powder.

12. The method as claimed in claim 6, wherein the application method comprises a welding process or a thermal spraying process.

13. The method as claimed in claim 6, wherein the melting point of the solder material is at least 20 K lower than that of the substrate.

14. The layer system as claimed in claim 7, wherein the substrate comprises a metallic substrate.

15. The layer system as claimed in claim 7, wherein the melting point of the solder material is at least 20 K lower than that of the substrate.

16. The sealing system as claimed in claim 8, wherein the layer system is on the rotating part.

17. The sealing system as claimed in claim 8, wherein the layer system is on a rotor blade.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The figures and the description present only working examples of the invention.

[0017] FIG. 1 shows a coated abrasive particle,

[0018] FIG. 2 shows a layer system.

DETAILED DESCRIPTION OF INVENTION

[0019] The particle 1 comprises a core of an abrasive particle 4, in particular cubic boron nitride (cBN), in its interior and a surrounding layer 7 of a metal, advantageously titanium (Ti) or nickel (Ni), which leads to better bonding in a solder material.

[0020] The term metal is intended to refer to metallic materials, i.e. including metallic alloys.

[0021] FIG. 2 schematically depicts a layer system 10.

[0022] The layer system 10 is advantageously a turbine component of a sealing system which is to have an abrasive layer 22 at one end.

[0023] The component as layer system 10 has a substrate 13, in particular a metallic superalloy and very particularly advantageously a nickel- or cobalt-based superalloy.

[0024] An abrasive layer 22 or a material comprising abrasive particles, in particular cubic boron nitride (cBN), is to be applied to the substrate 13, in particular to its surface 16. This should occur by means of a soldering process.

[0025] A solder material 19 in the form of a plasma spraying process, HVOF or a soldering paste or in the form of tapes, which comprises the particles 1 as per FIG. 1, is used here.

[0026] The applied solder material 19 then forms the outer layer 22. The solder material 19 has, in particular, a melting point which is at least 10 K lower, in particular at least 20 K lower, than that of the material of the substrate 13.

[0027] As melting point reducers in the solder, advantage is given to using typical elements such as boron (B), silicon (Si), phosphorus (P), hafnium (Hf), zirconium (Zr) or else manganese (Mn) and/or germanium (Ge).

[0028] The particles 1 are both entirely present in the layer 22 and also project from the surface of the layer 22.

[0029] The layer 22 thus comprises three different materials, namely that of the abrasive particle 4, that of the layer 7 around the particle 4 and the solder material 19.

[0030] The layer 22 is then advantageously applied only to the blade tip of a turbine rotor blade in such a sealing system.

[0031] The turbine rotor blade can have, and in the case of gas turbines will generally likewise have, metallic and/or ceramic coatings on the blade airfoil and/or on the blade platform, but these coatings do not comprise the particles 1.

[0032] The stator or the housing of a turbine, in particular a gas turbine, also has a protective coating into which this abrasive layer 22 rubs. The coating on the housing or stator can be purely metallic, purely ceramic or comprise a layer system of a metallic bonding layer and an outer ceramic layer or a plurality of ceramic layers.

[0033] The layers or the layer system of the housing are made so that they are mechanically softer than the abrasive layer 22, so as to allow grinding-in. This can be achieved via the composition of the metallic or ceramic coating and/or also by setting of the porosities of the layer or the layers and also advantageously by means of longitudinal grooves introduced by way of a laser beam or water jet.