Trivalent chromium electroplating liquid and electroplating method

A technology of electroplating solution and trivalent chromium, which is applied in the field of electroplating, can solve the problems of poor stability of the plating solution, achieve the effects of refining the coating grain, enhancing the bonding strength, and eliminating internal stress

Active Publication Date: 2016-11-09
WUHAN DESYTEK ENVIRONMENTAL PROTECTION NEW MATERIAL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Compared with the existing trivalent chromium electroplating method and technique, the electroplating solution of the present invention adopts a novel electroplating complexing agent, which overcomes the problem of using a small molecular carboxylic acid or its salt as a complexing agent in the existing trivalent chromium electroplating to cause the plating solution to The disadvantage of poor stability

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] Plating solution formula

[0026] Chromium sulfate 20g, acrylic acid-itaconic acid copolymer 4g (molecular weight 20,000), polyurea 1.0g, neodymium sulfate 0.4g, potassium sulfate 60g, mix well.

[0027] Electroplating process

[0028] Electroplating substrate 65Mn steel, using soft start, current density: 65 A / dm 2 , with iridium-tantalum-coated titanium as the anode, the area ratio of the cathode to the anode is 1:3, the working temperature is 25°C, the pH of the plating solution is 2.4, and the plating time is 2 hours.

[0029] Plating index:

[0030] Bright and dense coating, coating thickness 50μm, hardness 850HV at room temperature, after 5min, 200℃ heat treatment, hardness 1600HV, no cracking in 300℃ thermal shock test.

Embodiment 2

[0032] Plating solution formula

[0033] Chromium sulfate 40g, acrylic acid-itaconic acid-methacrylic acid-2-hydroxyethyl ester copolymer 1g (molecular weight 5000), urea 2.0g, neodymium sulfate 0.1g, potassium sulfate 30g, mix well.

[0034] Electroplating process

[0035] Electroplating substrate 65Mn steel, using soft start, current density: 15 A / dm 2 , with iridium-tantalum-coated titanium as the anode, the area ratio of the cathode to the anode is 1:1, the working temperature is 65°C, the pH of the plating solution is 3.0, and the plating time is 2 hours.

[0036] Plating index:

[0037] Bright and dense coating, coating thickness 75μm, hardness 900HV at room temperature, after 5min, 200℃ heat treatment, hardness 1750HV, no cracking in 300℃ thermal shock test.

Embodiment 3

[0039] Plating solution formula

[0040] Chromium sulfate 50g, acrylic acid-maleic acid copolymer 4g (molecular weight 10000), 0.5g polyethylene glycol (molecular weight 1000), 0.5g neodymium sulfate, 100g potassium sulfate, mix well.

[0041] Electroplating process

[0042] Electroplating substrate 65Mn steel, using soft start, current density: 35 A / dm 2 , with iridium-tantalum-coated titanium as the anode, the area ratio of the cathode and the anode is 1:2, the working temperature is 35°C, the pH of the plating solution is 2.8, and the plating time is 2.5 hours.

[0043] Plating index:

[0044] Bright and dense coating, coating thickness 90μm, hardness 950HV at room temperature, after 5min heat treatment at 200℃, hardness 1850HV, no cracking in thermal shock test at 300℃.

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Abstract

The invention relates to trivalent chromium electroplating liquid and an electroplating method, and belongs to the field of electroplating. Each liter of electroplating liquid comprises the following components: any one or several of chromium potassium sulfate, chromium sulfate and alkaline chromium sulfate of 20-80 g, complexing agent of 1-10 g, wetting agent of 0.5-5.0 g, stress eliminating agent of 0.1-0.5 g, and electric conducting salt of 30-150 g; and the complexing agent is polycarboxylic acid or polycarboxylic acid containing hydroxyl. When the electroplating liquid is used for electroplating trivalent chromium, the defect of cracking of a plating layer above 35 microns can be prevented. The uniform and compact plating layer of 50-150 microns can be obtained; and the hardness of the plating layer is 850-1000 HV. After the plating layer is heated by 5 min at 200 DEG C, the hardness reaches 1600-2000 HV.

Description

technical field [0001] The invention relates to a trivalent chromium electroplating solution and an electroplating method, belonging to the field of electroplating. Background technique [0002] Depositing metal chromium coating on the metal surface by electroplating can significantly improve the corrosion resistance, wear resistance, surface hardness and decoration of the metal substrate, so electroplating chromium is widely used in the electroplating industry. At present, except for decorative chromium plating, hexavalent chromium plating is basically used to enhance the corrosion resistance, wear resistance and surface hardness of the substrate. However, hexavalent chromium is highly toxic and pollutes the environment seriously, and the waste liquid of hexavalent chromium electroplating is difficult to deal with. Developed countries such as Europe and the United States have made strict regulations on the discharge of hexavalent chromium. For these reasons, people are loo...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C25D3/06
CPCC25D3/06
Inventor 陆飚李家柱
Owner WUHAN DESYTEK ENVIRONMENTAL PROTECTION NEW MATERIAL CO LTD
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