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Method of pulse chromium plating with trivalent chromium

A trivalent chromium and pulse technology, applied in the field of electrochemistry, can solve the unfavorable problems of clean production in the electroplating industry, and achieve the effect of improving wear resistance

Inactive Publication Date: 2010-07-21
SHANGHAI INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The chloride solution system and the sulfate-chloride mixed solution system are used for chrome plating, and the anode will affect the environment due to the generation of chlorine gas, which is not conducive to the clean production of the electroplating industry.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] Weigh 2.9258g of praseodymium oxide in a 100mL small beaker, add 15mL of concentrated nitric acid under stirring, heat to dissolve it, after cooling, transfer to a 50mL volumetric flask, dilute to the mark with water, the concentration of praseodymium in this solution is 50g / L.

[0027] In a 1L beaker, add 200g of chromium sulfate, 150g of aluminum sulfate, 30g of sodium fluoride, 30g of urea, 30g of malic acid, add 985mL of water to dissolve, add 3mL of the above solution of praseodymium concentration of 50g / L, stir well, and use sodium bicarbonate Adjust the pH of the solution to 1, transfer it into a 1L volumetric flask, and dilute to the mark with water to prepare a plating solution.

[0028] Transfer the above electroplating solution into a 1L beaker, put the 80mm×80mm×0.5mm steel plate to be plated into the electroplating solution and serve as the cathode. The anode is a 150mm×100mm×2mm Ir-Ta oxide-coated Ti plate, magnetically stirred , The stirring speed is 100rpm, ...

Embodiment 2

[0032] Weigh 2.2870g of erbium oxide in a 100mL small beaker, add 12mL of concentrated nitric acid under stirring, heat to dissolve it, after cooling, transfer to a 50mL volumetric flask, dilute to the mark with water, the concentration of erbium in the solution is 20g / L.

[0033] Add 400g of potassium chromium sulfate, 300g of aluminum sulfate, 50g of sodium fluoride, 300g of urea, 50g of acetic acid, 50g of lactic acid in a 1L beaker, add 935mL of water to dissolve, add 50mL of the above-mentioned erbium concentration of 20g / L solution, stir well, use Adjust the pH of the solution with sodium bicarbonate solution to 2.5, transfer it into a 1L volumetric flask, and dilute to the mark with water to prepare an electroplating solution.

[0034] Transfer the above electroplating solution into a 1L beaker, put the 80mm×80mm×0.5mm steel plate to be plated into the electroplating solution and serve as the cathode. The anode is a 150mm×100mm×2mm Ir-Ta oxide-coated Ti plate, magnetically s...

Embodiment 3

[0038] Weigh 2.8775g of terbium oxide in a 100mL small beaker, add 15mL of concentrated nitric acid under stirring, heat to dissolve it, after cooling, transfer to a 50mL volumetric flask, dilute with water to the mark, the concentration of terbium in the solution is 50g / L;

[0039] Weigh 2.8816g gadolinium oxide in a 100mL small beaker, add 15mL concentrated nitric acid under stirring, heat to dissolve it, after cooling, transfer to a 50mL volumetric flask, dilute to the mark with water, the concentration of gadolinium in the solution is 50g / L.

[0040] Add 300g of potassium chromium sulfate, 200g of aluminum sulfate, 40g of sodium fluoride, 200g of urea, 30g of glycine, 30g of succinic acid in a 1L beaker, add 865mL of water to dissolve, add 25mL of the solution of terbium concentration of 50g / L and the above 35mL of a solution with a gadolinium concentration of 50g / L, stir evenly, adjust the pH of the solution to 3 with sodium bicarbonate solution, transfer it into a 1L volumet...

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Abstract

The invention discloses a method of pulse chromium plating with trivalent chromium, which comprises the following steps: dissolving an rare-earth oxide in an acid to prepare a rare-earth salt solution; dissolving chromium sulfate salt, aluminum sulfate, sodium fluoride, urea and a complexing agent in water, and then adding the rare-earth salt solution to prepare an electroplating solution containing the chromium sulfate salt, the aluminum sulfate, the sodium fluoride, the urea, the complexing agent and the rare-earth salt; putting a part to be plated in the electroplating solution for electroplating, and controlling the electroplating process conditions as follows: the current density is 28-90A / dm<2>, the pH value of the electroplating solution is 1-4, the temperature is 25-60 DEG C, the agitating speed is 100-600 rpm, the plating time is 30-90 min, the duty ratio is 5-100%, and the pulse frequency is 100-5000 Hz; and after electroplating, washing the plated part with water and drying with air, thereby finishing pulse chromium plating with trivalent chromium of the part to be plated. The hardness and wear resistance of the obtained chromium coating are obviously improved, wherein the hardness is larger than or equal to 960HV, and the mass loss during wear is less than or equal to 0.03mg.

Description

Technical field [0001] The invention relates to a method for pulse chromium plating with trivalent chromium, which belongs to the technical field of electrochemistry. Background technique [0002] The chromium plating layer has good hardness, wear resistance, corrosion resistance and decorative appearance. It is not only used for decorative plating, but also widely used for functional plating, so it is listed as one of the three major plating types. The chromic acid in the traditional hexavalent chromium solution is highly toxic, is a strong carcinogen, and pollutes the environment. In order to replace the hexavalent chromium electroplating process, people have conducted a lot of research on trivalent chromium electroplating. The current trivalent chromium plating system mainly includes sulfate solution system, chloride solution system and sulfate-chloride mixed solution system. Chloride solution system and sulfate-chloride mixed solution system are used for chromium plating. T...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C25D3/06C25D5/18
Inventor 刘小珍李昕
Owner SHANGHAI INST OF TECH
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