Nickel plating process method of magnesium alloy

A process method, magnesium alloy technology, applied in metal material coating process, liquid chemical plating, anodic oxidation, etc., can solve the limited improvement of magnesium alloy corrosion resistance and wear resistance, magnesium alloy substrate corrosion, substrate and Coating galvanic corrosion and other problems to achieve the effect of avoiding galvanic corrosion, preventing damage, and overcoming uniformity and adhesion

Inactive Publication Date: 2011-08-03
HARBIN ENG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

So far, the protection of magnesium alloys by a single protection process either has fatal flaws, or the improvement of the corrosion resistance and wear resistance of magnesium alloys is relatively limited.
Using the existing nickel plating process for magnesium alloys, the electroless nickel plating layer is an amorphous protective layer, which has excellent wear resistance, corrosion resistance, etc., but is prepared directly on the surface of magnesium alloys. When coating, it is easy to cause galvanic corrosion of the substrate and the coating
Moreover, SO 4 2- , Cl - Corrosion of magnesium alloy substrate

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0013] A nickel plating process for magnesium alloys, comprising the following steps:

[0014] (1) Perform plasma electrolytic oxidation on the pretreated magnesium alloy; the oxidation is controlled by constant current, and the current density is 0.5A / dm 2 , the solution temperature is 20°C, the oxidation time is 50 minutes; the solution ratio: 18g / L Na 2 SiO 3 , 6.8g / L of sodium citrate, 6g / L of KaF and 15g / L of NaAlO 2 .

[0015] After step (1), the thermal shock test results show that the bonding force between the oxide layer and the substrate is excellent.

[0016] (2) activation and reduction; the PdCl of 0.5g / L 2 , 1g / L NaCl and 4g / L EDTA to make an activation solution, use a water bath to heat the solution to 35°C, immerse the sample that has been oxidized and cleaned by plasma electrolysis into the above activation solution, and the activation time is 10 minutes ; Rinse with deionized water after activation. Then carry out reduction treatment with 2.5wt% sodium ...

Embodiment 2

[0026] A nickel plating process for magnesium alloys, comprising the following steps:

[0027] (1) Perform plasma electrolytic oxidation on the pretreated magnesium alloy; the oxidation is controlled by constant current, and the current density is 1.2A / dm 2 , the solution temperature is 40°C, the oxidation time is 35 minutes; the solution ratio: 25g / L Na 2 SiO 3 , 10.5g / L sodium citrate, 9g / L KaF and 18g / L NaAlO 2 .

[0028] (2) Activation and reduction; the PdCl of 1g / L 2 , 3g / L NaCl and 6g / L EDTA to make an activation solution, use a water bath to heat the solution to 30°C, immerse the sample that has been oxidized and cleaned by plasma electrolysis into the above activation solution, and the activation time is 5 minutes ; Rinse with deionized water after activation. Then carry out reduction treatment with 3wt% sodium hypophosphite solution to reduce palladium ions to obtain the catalytic center of electroless nickel plating.

[0029] (3) Nickel plating on the surface; t...

Embodiment 3

[0031] A nickel plating process for magnesium alloys, comprising the following steps:

[0032] (1) Perform plasma electrolytic oxidation on the pretreated magnesium alloy; the oxidation is controlled by constant current, and the current density is 0.8A / dm 2 , the solution temperature is 30°C, the oxidation time is 45 minutes; the solution ratio: 20g / L Na 2 SiO 3 , 8.2g / L of sodium citrate, 7.5g / L of KaF and 16g / L of NaAlO 2 .

[0033] (2) activation and reduction; the PdCl of 0.8g / L 2 , 2g / L NaCl and 5g / L EDTA to make an activation solution, use a water bath to heat the solution to 32°C, immerse the sample that has been oxidized and cleaned by plasma electrolysis into the above activation solution, and the activation time is 8 minutes ; Rinse with deionized water after activation. Then carry out reduction treatment with 2.7wt% sodium hypophosphite solution to reduce palladium ions to obtain the catalytic center of electroless nickel plating.

[0034] (3) Nickel plating o...

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Abstract

The invention provides a nickel plating process method of magnesium alloy, which comprises the following steps: (1) plasma electrolytic oxidation for the magnesium alloy after being pre-treated; (2) activation and reduction, in which 0.5-1g / L of PdCl2, 1-3g / L of NaCl and 4-6g / L of EDTA (ethylenediaminetetraacetic acid) are prepared into an activation solution, heated up to 30 DEG C 35 DEG Cbelow zero and activated for 5 to 10 minutes; cleaning with deionized water after the completion of activation; and then carrying out the reduction treatment with 2.5wt%-3wt% of sodium hypophosphite solution and obtaining the catalytic center of electroless nickel plating; and (3) surface nickel plating. The invention adopts the plasma electrolytic oxidation process before electroless nickel plating so as to prevent the galvanic corrosion of a substrate and a coating; nickel acetate is used to prepare a plating solution of the electroless nickel plating, and the pH value of the solution is 6.2 to 6.5, so that the defects that SO4<2-> and Cl<-> cause corrosion to the magnesium alloy substrate when nickel sulfate and nickel chloride are used to prepare the plating solution in the ordinary electroless plating process can be overcome.

Description

technical field [0001] The invention relates to a surface treatment method for a magnesium alloy, in particular to a nickel plating process for a magnesium alloy. Background technique [0002] The density of magnesium is 1.74g / cm 3 , Magnesium alloy is the lightest among metal structural materials, its specific strength is higher than some high-strength steel and aluminum alloy, and it also has good castability, electric shielding, shock resistance and shock absorption, non-toxic and recyclable, etc. , known as "21st century green engineering metal". In order to reduce the energy consumption of automobiles and reduce exhaust emissions, it is an inevitable choice to replace steel components on automobiles with magnesium alloys. Magnesium alloys are receiving more and more attention in the automobile industry. Magnesium alloys have been applied to components such as intake manifolds and camshaft covers. Some experts believe that the magnesium alloy used in each car may reac...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C23F17/00C25D11/06C23C18/36
Inventor 曾立云王俊一杨世伟郭亚欢施月杰
Owner HARBIN ENG UNIV
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