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Method for deposition of chromium layers as hard- chrome plating, electroplating bath and hard- chrome surfaces

A technology of electroplating solution and hard chrome, which is applied in the direction of electrolysis process, electrolysis components, transportation and packaging, etc. It can solve the problems that the chromium layer does not meet the known requirements of processing, cannot provide quality, and the hardness cannot reach the layer hardness.

Inactive Publication Date: 2009-08-19
FRAUNHOFER GESELLSCHAFT ZUR FOERDERUNG DER ANGEWANDTEN FORSCHUNG EV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] 1. Chromium layers deposited by previously known methods do not comply with the known requirements for hard chrome treatments with layer thicknesses above 5 μm
[0010] 2. The hardness of the layers that can be deposited from these electroplating solutions cannot reach the required layer hardness of at least 800HV above
[0011] 3. With regard to the reproducibility of the layers that can be deposited, known electroplating solutions do not provide the quality obtained from chromium(VI) containing electrolytes

Method used

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  • Method for deposition of chromium layers as hard- chrome plating, electroplating bath and hard- chrome surfaces
  • Method for deposition of chromium layers as hard- chrome plating, electroplating bath and hard- chrome surfaces
  • Method for deposition of chromium layers as hard- chrome plating, electroplating bath and hard- chrome surfaces

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0038] Coating from ammonium chrome alum using glycine

[0039] Composition of catholyte and anolyte

[0040] catholyte :

[0041] 400 g / l ammonium chromium alum, the chromium content corresponds to 10.6% by mass.

[0042] 40g / l boric acid

[0043] 80g / l glycine

[0044] 0.5g / l sodium lauryl sulfate

[0045] Anolyte :

[0046] 30% H soluble in water 2 SO 4

[0047] Preparation of catholyte :

[0048] Add deionized water to ammonium chromium alum (prepared according to N. Rempfer, H-W Lerner, M. Bolte, ActaCryst. (2004), E60, i80-i81) and heat at 80° C. for 2 hours. After cooling the ammonium chromium alum solution to 40°C, boric acid and glycine were added to the electrolyte. Subsequently, before the first coating, the pH was adjusted to pH 2.25 by adding ammonia water. The pH measurement equipment used was calibrated at 40 °C.

[0049] Electroplating chromium deposition was carried out in a coating chamber where the anolyte (30% sulfuric acid) was separated fr...

Embodiment 2

[0057] Coating from ammonium chrome alum using diethanolamine

[0058] Same as Example 1, replace glycine with diethanolamine

[0059] The electrolyte mixture and sample pretreatment were consistent with Example 1. Glycine was replaced by 1.1 mol / l diethanolamine as a complex forming agent.

[0060] During the test, the pH was maintained between pH 2.3 and pH 2.5.

[0061] Result: Layer thickness 58.5 μm, measured with an optical microscope (Zeiss-Axioplan)

[0062] Hardness measured on a microhardness tester (Anton Paar-MH-T4) is 855HV

[0063] The test load is 50p, 10s, 5p / s

Embodiment 3

[0065] Coating from chromium sulfate:

[0066] The test was the same as in Example 1, except that ammonium chromium alum was replaced by chromium (III) sulfate with a concentration of 40g Cr / l.

[0067] Result: layer thickness 39.8 μm; measured with an optical microscope (Zeiss-Axioplan)

[0068] Hardness measured on a microhardness tester (Anton Paar-MH-T4) to 901HV

[0069] The test load is 50p, 10s, 5p / s

[0070] (see Figure 5 )

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Abstract

The invention relates to a method for deposition of chromium layers as hard-chrome plating for protection against wear or corrosion and / or for decorative purposes and also an electroplating bath with which chromium layers of this type can be deposited. The invention also relates to hard-chrome surfaces produced accordingly.

Description

technical field [0001] The invention relates to a method for depositing a chromium layer as hard chromium plating for wear protection or corrosion protection and / or for decorative purposes, and also to an electroplating bath for depositing such a chromium layer. The invention also relates to the hard chrome surfaces thus produced. Background technique [0002] In the commercial processes for producing thick chromium coatings hitherto known from the prior art, practically only electrolytes are used in which the chromium to be deposited is present in the hexavalent state. [0003] Efforts have been made to study chromium since the beginning of electrolytic deposition of chromium with chromium(III) electrolyte instead of toxic chromium(VI) electrolyte. Attempts to replace chromium(VI) compounds with chromium(III) compounds began with the fact that chromium(VI) compounds entering the body can cause serious health problems. In addition to the health and environmental aspects, t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C25D3/06C25D21/12C25D17/00
CPCC25D21/12C25D3/06C25D17/002C25D17/00Y10T428/12847
Inventor 延斯·博纳特马丁·梅茨纳赫尔维希·克拉斯尼特兹卡尔·谢默尔曼斯
Owner FRAUNHOFER GESELLSCHAFT ZUR FOERDERUNG DER ANGEWANDTEN FORSCHUNG EV