Method for the production of electroplated components

Abstract

Disclosed is a method for the production of electroplated components. In the disclosed method, an edge layer of a component to be coated is subjected to a mechanical treatment in which the edge layer is deformed at least in portions, consequently the structure of the edge layer being modified at least in portions and hydrogen traps being produced in the modified portions of the edge layer.

Claims

1. A method for producing electroplated components, in which a) an edge layer of a component to be coated is subjected to a mechanical treatment, in which the edge layer is deformed at least in portions, consequently the structure of the edge layer being modified at least in portions and, in the modified portions of the edge layer, hydrogen traps being produced, and b) at least on a part of the surface of the mechanically treated edge layer of the component to be coated, a coating is electrodeposited, hydrogen being released during the electrodeposition which penetrates into the mechanically treated edge layer at least partially, the hydrogen traps produced in the modified portions of the edge layer essentially binding the totality of the hydrogen penetrating into the mechanically treated edge layer during the electrodeposition in step b); wherein it is determined or estimated before step a) what volume of hydrogen will penetrate into the mechanically treated edge layer during the electrodeposition in step b), and the mechanical treatment in step a) is effected such that the total volume of the hydrogen traps produced in the modified portions of the edge layer is greater than or equal to the volume of hydrogen determined or estimated before step a).

2. The method according to claim 1, wherein the mechanical treatment in step a) is effected by shot peening, by rolling, by hammering, by material-removing machining, or by a combination thereof.

3. The method according to claim 1, wherein the component to be coated comprises a crystalline material.

4. The method according to claim 3, wherein the crystalline material is selected from the group consisting of metals, semimetals, ceramics and mixtures thereof.

5. The method according to claim 1, wherein the coating is a coating made of a metal or of a metal alloy, the metal and/or the metal alloy being selected from the group consisting of gold, silver, iron, chromium, nickel, copper, cadmium, palladium, zinc, and mixtures and alloys thereof.

6. The method according to claim 1, wherein, during the mechanical treatment in step a), the structure of the edge layer is modified, at least in portions, to a depth of more than 0.01 mm, and hydrogen traps are produced in the modified portions of the edge layer.

7. The method according to claim 1, wherein it is determined or estimated, before step a), to what depth the hydrogen will penetrate into the mechanically treated edge layer during the electrodeposition in step b), and the mechanical treatment in step a) is effected such that the hydrogen traps produced in the edge layer are produced at least in the portions, the surface of which is intended to be coated in step b), to this depth determined or estimated before step a).

8. The method according to claim 7, wherein the determination of the depth is effected before step a) by the surface of the edge layer of a further component which consists of the same material as the component to be coated, being provided with an electroplating, at least in portions, which consists of the same material as the electroplating in step b) and, directly thereafter, by the depth course of the hydrogen content in the edge layer being analysed.

9. The method according to claim 1, wherein, after step a) and before step b), a chemical pre-treatment of the surface of the component to be coated is implemented, the chemical pre-treatment of the surface of the component to be coated being selected from the group consisting of de-greasing the surface, etching the surface, pickling the surface, activating the surface and a combination thereof.

10. A method for producing electroplated components, in which a) an edge layer of a component to be coated is subjected to a mechanical treatment, in which the edge layer is deformed at least in portions, consequently the structure of the edge layer being modified at least in portions and, in the modified portions of the edge layer, hydrogen traps being produced, and b) at least on a part of the surface of the mechanically treated edge layer of the component to be coated, a coating is electrodeposited, hydrogen being released during the electrodeposition which penetrates into the mechanically treated edge layer at least partially, the hydrogen traps produced in the modified portions of the edge layer essentially binding the totality of the hydrogen penetrating into the mechanically treated edge layer during the electrodeposition in step b); wherein it is determined or estimated, before step a), to what depth the hydrogen will penetrate into the mechanically treated edge layer during the electrodeposition in step b), and the mechanical treatment in step a) is effected such that the hydrogen traps produced in the edge layer are produced at least in the portions, the surface of which is intended to be coated in step b), to this depth determined or estimated before step a).

11. The method according to claim 10, wherein the determination of the depth is effected before step a) by the surface of the edge layer of a further component which consists of the same material as the component to be coated, being provided with an electroplating, at least in portions, which consists of the same material as the electroplating in step b) and, directly thereafter, by the depth course of the hydrogen content in the edge layer being analysed.

12. The method according to claim 10, wherein the mechanical treatment in step a) is effected by shot peening, by rolling, by hammering, by material-removing machining, or by a combination thereof.

13. The method according to claim 10, wherein the component to be coated comprises a crystalline material.

14. The method according to claim 13, wherein the crystalline material is selected from the group consisting of metals, semimetals, ceramics and mixtures thereof.

15. The method according to claim 10, wherein the coating is a coating made of a metal or of a metal alloy, the metal and/or the metal alloy being selected from the group consisting of gold, silver, iron, chromium, nickel, copper, cadmium, palladium, zinc, and mixtures and alloys thereof.

Description

EMBODIMENT 1

(1) The first embodiment relates to the avoidance of hydrogen embrittlement of a hardened steel after electroplating by machining-caused increase in the trap density.

(2) In this case, the application of the present invention for embrittlement-proof electrodeposition of a thin (<50 μm) hard chromium layer on a hardened steel sample is illustrated. The steel sample was hard-turned with machining parameters which were chosen from the point of view of economic machining.

(3) Firstly, the edge layer state is characterised by means of X-ray analyses. Normal hard-machining parameters are associated with high heat effect and the formation of unfavourable intrinsic tensile stresses, the predominant heat influence does not lead to a significantly increased trap density.

(4) This sample is coated with hard chromium according to the state of the art, which leads to a hydrogen input.

(5) Directly after the coating, the hydrogen depth profile is determined by means of GDOES (Glow Discharge Emission Spectroscopy). Because of the low layer thickness and the short coating time, only a near-surface hydrogen input up to approx. 0.1 mm can be expected. Furthermore, the proportion of bound hydrogen is determined by TDS.

(6) As a result of changed parameters of the hard-turning on a further sample, the dislocation density and hence the trap density in the edge layer is increased.

(7) In a further coating test on this sample, the binding of the hydrogen in the edge layer treated according to the invention is examined by means of GDOES and, by means of TDS, the predominant binding of the hydrogen and the small degree of residual diffusible hydrogen is ensured.

EMBODIMENT 2

(8) The second embodiment relates to the avoidance of hydrogen embrittlement of a hardened steel after electroplating by increasing the trap density by means of hammering.

(9) In this case, the application of the invention for embrittlement-proof electrodeposition of a thick (>100 μm) hard chromium layer on a hardened steel sample is presented.

(10) Firstly, the edge layer state is characterised by means of X-ray analyses. Without a strengthening surface treatment, such as shot peening, hammering or deep rolling, increased dislocation- or trap densities can generally be attributed to the metal-removing end machining with effect depths<0.2 mm. A sample is coated according to the state of the art with a thick hard chromium layer, as is often used for wear-protection purposes, which leads to a significant and deep-reaching hydrogen input.

(11) A deep-reaching hydrogen input cannot be determined by means of GDOES, the analysis depth of GDOES is generally restricted to 0.1 mm. For this reason, thin sample strips are removed from the edge of the sample, below the coating, and the total hydrogen content is determined by means of hot extraction and the non-bound hydrogen component by means of TDS. As a result, a hydrogen input can also be demonstrated in greater depths.

(12) By hammering, a further sample is surface-treated. Increased dislocation densities up to several millimetres depth can thereby be achieved and demonstrated by means of X-ray diffraction.

(13) After the electroplating of this sample, the binding of the hydrogen in the edge layer treated according to the invention is tested by means of TDS and hot extraction.