Trivalent chromium electroplating solution of sulfate system and electroplating method thereof

An electroplating solution and technology of trivalent chromium, applied in the field of electroplating of the electroplating solution, can solve the problems of hexavalent chromium electroplating process, such as high toxicity, poor dispersion ability and covering ability, and inevitable pollution of the environment, so as to achieve bright appearance and maintain acidity , to ensure the effect of continuous thickening

Inactive Publication Date: 2010-03-10
NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The current traditional hexavalent chromium plating technology is still widely used, and there are many defects, such as poor dispersion and coverage, low current efficiency, high plating temperature, the most important problem is that the hexavalent chromium plating process has high toxicity, heavy pollution, and waste water. It is difficult to deal with and seriously pollutes our country's water, soil and atmospheric environment. Several major countries in the world have successively promulgated laws to restrict or prohibit electroplating processes related to hexavalent chromium. For example, the European Parliament and the Council issued the RoHS directive on January 23, 2003. Europe will completely prohibit the circulation of electronic and electrical equipment containing hexavalent chromium in the European market on July 1, 2006; the U.S. Environmental Protection Agency will completely ban the hexavalent chromium electroplating process before 2010; "Regulates to control the use of hexavalent chromium from March 2007
[0003] At present, the technology to replace hexavalent chromium electroplating mainly includes electrodeposition alloy coating and trivalent chromium electroplating. Among them, trivalent chromium electroplating has low toxicity, only one percent of hexavalent chromium, low energy consumption, good dispersion ability and covering perfo

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0050] Take 0.2mol of chromium sulfate, dissolve it in distilled water, and stir until completely dissolved; take 0.5mol of boric acid, dissolve it in distilled water at 60°C, and stir until dissolved; mix the above obtained chromium sulfate solution with boric acid solution, and stir; add 0.5mol of Ammonium formate and glycine, stirred at 60°C for 0.5 hours, then added 0.5mol potassium sulfate, 0.3mol sodium hypophosphite, 0.02mol ammonium bromide, 0.01mol ferrous sulfate, 0.01mol thickening agent, and stirred while adding , until completely dissolved, and stand still for 12 hours; add water to nearly 1L; then check and adjust the pH value of the plating solution to 1.0 with ammonia water or sulfuric acid solution; after constant volume, control the temperature at 30°C, and pretreat the workpiece according to the conventional pre-plating pretreatment After cleaning, rust removal and activation, at 10A / dm 2 Plating at current density for 20 minutes, take it out and rinse it wi...

Embodiment 2

[0052] Take 0.4mol of chromium sulfate, dissolve it in distilled water, and stir until completely dissolved; take 0.8mol of boric acid, dissolve it in distilled water at 65°C, and stir until dissolved; mix the above obtained chromium sulfate solution with boric acid solution, and stir; add 1.0mol of Sodium acetate and nitrilotriacetic acid were stirred at 55°C for 1 hour, and then 1.0mol potassium sulfate, 0.5mol sodium hypophosphite, 0.2mol ammonium bromide, 0.02mol ferrous sulfate, and 0.2mol thickening agent were added in sequence Stir until completely dissolved, then stir at a constant temperature of 60°C for 3 hours, and stand still for 18 hours; add water to nearly 1L; then check and adjust the pH of the plating solution to 1.5 with ammonia water or sulfuric acid solution; after constant volume, control the temperature at 40°C, and The workpiece is degreased, washed with water, acid-etched and washed with water in sequence, at 40A / dm 2 Electroplating under current densit...

Embodiment 3

[0054] Take 0.5mol of chromium sulfate, dissolve it in distilled water, and stir until completely dissolved; take 1.2mol of boric acid, dissolve it in 70°C distilled water, and stir until dissolved; mix the above obtained chromium sulfate solution with boric acid solution, and stir; add 1.5mol of Succinic acid and aminoacetic acid were stirred at 60°C for 1.5 hours, and then 1.2mol potassium sulfate, 0.04mol ferrous sulfate, 0.8mol sodium hypophosphite, 0.3mol ammonium bromide, 0.05mol ferrous sulfate, and 0.4mol Add thickener, stir while adding, then stir for 4 hours at a constant temperature of 60°C, and stand still for 24 hours; add water to nearly 1L; then check and adjust the pH of the plating solution to 2.5 with ammonia water or sulfuric acid solution; after constant volume, control the temperature at 35°C , the workpiece is degreased, washed with water, acid-etched and washed with water in sequence, at 30A / dm 2 Electroplate for 2 hours under current density, rinse with...

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PUM

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Abstract

The invention provides a trivalent chromium electroplating solution of a sulfate system. The trivalent chromium electroplating solution is characterized by comprising the following components in molarconcentration (mol/L): chromium sulfate0.2-0.6, potassium sulfate 0.5-1.5, ammonium bromide 0.02-0.5, boric acid 0.5-1.2, sodium hypophosphite 0.1-1, ferrous sulfate 0.01-0.1, complexing agent 0.2-2.0, thickening agent 0.01-0.5 and the balance of water. The invention also discloses an electroplating method for the electroplating solution. Compared with the prior art, the electroplating solution and the electroplating method have the advantages that: the electroplating solution is clean and pollution free, the thickness of the plating layer reaches 20 to 80mu m, the plating layer is smooth with few cracks and high bonding force, the source of raw materials is rich, the cost is lower, the performance-to-price ratio is good, the electroplating solution can be continuously used for electroplating for 0.5 to 5 hours, the hardness of the plating layer is 600 to 700HV, and after thermal treatment, the hardness of the plating layer can reach 1,200HV.

Description

technical field [0001] The invention relates to a trivalent chromium electroplating solution of a sulfate system, and also relates to an electroplating method of the electroplating solution. Background technique [0002] The existing chromium plating layer has high hardness, good wear resistance, corrosion resistance and decorative properties, and is one of the most widely used plating types in the electroplating industry. The current traditional hexavalent chromium plating technology is still widely used, and there are many defects, such as poor dispersion and coverage, low current efficiency, high plating temperature, the most important problem is that the hexavalent chromium plating process has high toxicity, heavy pollution, and waste water. It is difficult to deal with and seriously pollutes our country's water, soil and atmospheric environment. Several major countries in the world have successively promulgated laws to restrict or prohibit electroplating processes relat...

Claims

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Application Information

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IPC IPC(8): C25D3/06
Inventor 李保松倪浩明乌学东邵佳敏
Owner NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI
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