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Chemical nickel-plating method on magnesium alloy surface

A technology of electroless nickel and magnesium alloy plating, applied in the field of electroless nickel plating on magnesium alloys, can solve the problems of poor bonding between the coating and the magnesium alloy substrate, failure to ensure high corrosion resistance of the coating, and affecting the quality of the electroless coating, so as to ensure the coating Thickness and quality, low cost, easy to control effect

Inactive Publication Date: 2007-03-14
INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, due to the high chemical activity of magnesium and its alloys, after the workpiece enters the electroless nickel plating solution, strong corrosion and replacement reactions occur, accompanied by a large amount of hydrogen evolution, resulting in poor bonding between the coating and the magnesium alloy substrate, resulting in local blistering Or convex peeling, these defects seriously affect the quality of the electroless plating layer and the quality of the subsequent electroplating layer, and cannot guarantee the high corrosion resistance of the plating layer
The pretreatment process of traditional electroless nickel plating on magnesium alloys is complicated, and generally requires steps such as zinc immersion, cyanide copper plating, etc., especially the cyanide copper plating solution contains cyanide, which is extremely toxic

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] Electroless Nickel Plating on Magnesium Alloy

[0028] The sample is an extruded AZ31D magnesium alloy, and the specific operation steps are as follows:

[0029] 1. Mechanical pretreatment: Grinding with sandblasting or sandpaper to remove burrs, firm oxides, lubricants for extrusion, release agents, casting sand, cutting oil and other foreign matter, reduce surface roughness; wash with water;

[0030] 2. Degreasing: wash with a compound solution of 10g / l sodium hydroxide, 15g / l sodium phosphate, and 15g / l sodium carbonate to remove general dirt, lubricants, cutting agents, etc. 5 minutes; wash with water;

[0031] 3. Pickling: wash with concentrated hydrofluoric acid and phosphoric acid in a volume ratio of 1:1 to remove scale, corrosion products, sintered and attached lubricants, lubricants that have not been removed during degreasing, Steel shot, foundry sand and other dirt; the temperature is 30°C, the time is 1 minute; wash with water;

[0032] 4. Activation or ...

Embodiment 2

[0039] The pretreatment method is the same as in Example 1.

[0040] The difference from Example 1 is: die-casting AZ91D magnesium alloy is used;

[0041] The degreasing temperature is controlled at 90°C and the time is 10 minutes; the pickling temperature is 20°C and the time is 5 minutes; the activation or finishing temperature is 30°C and the time is 2 minutes.

[0042] 1. Electroless plating pretreatment: immerse the pretreated magnesium alloy sample in the electroless plating pretreatment solution, the solution consists of hydrofluoric acid, potassium fluoride, ferrous nitrate and sodium tartrate (12% fluorosilicate, sodium fluoride 2g / l, ferrous nitrate 9g / l and sodium tartrate 10g / l). Control the temperature at 30°C and soak for 15 minutes to obtain a gray fluoride film; wash with water;

[0043] 2. One-step electroless nickel plating: immerse the pretreated workpiece in a solution containing basic nickel carbonate, sodium hypophosphite, citric acid, lactic acid, sodi...

Embodiment 3

[0047] The pretreatment method is the same as in Example 1.

[0048] The difference from Example 1 is that the sample is an extruded AM60 magnesium alloy;

[0049] The degreasing temperature is controlled at 70°C and the time is 7 minutes; the pickling temperature is 60°C and the time is 0.5 minutes; the activation or finishing temperature is 25°C and the time is 10 minutes;

[0050] 1. Electroless plating pretreatment: immerse the pretreated magnesium alloy sample in the described electroless plating pretreatment solution, solution is made up of fluosilicic acid, acidic ammonium fluoride, ammonium ferrous sulfate and tartaric acid (8% of fluosilicic acid, Acid ammonium fluoride 15g / l, ammonium ferrous sulfate 10g / l and tartaric acid 5g / l). Control the temperature at 30°C and soak for 12 minutes to obtain a gray-white fluoride film; wash with water;

[0051] 2. One-step electroless nickel plating: immerse the pretreated workpiece into nickel sulfate 20g / l, sodium hypophosphi...

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Abstract

The present invention relates to magnesium alloy surface treating technology, and is especially chemical nickel plating process for magnesium alloy. The operation process includes the following steps: activating or finishing magnesium alloy through polishing or grinding, degreasing and acid pickling with acid fluoride bearing solution at 20-60 deg.c for 0.5-5 min; pre-treating with water solution containing fluoride bearing compound, iron bearing compound and complex at 15-45 deg.c for 5-30 min; and chemically nickel plating. The said process can make chemical nickel coating with homogeneous thickness, firm combination with substrate, high corrosion resistance and metal appearance. The process of the present invention has low cost and less environmental pollution and is suitable for industrial production.

Description

technical field [0001] The invention relates to a magnesium alloy surface treatment technology, in particular to a method for electroless nickel plating on a magnesium alloy. Background technique [0002] Magnesium alloy has small specific gravity, high specific strength and specific stiffness, good thermal and electrical conductivity, good damping and shock absorption and electromagnetic shielding functions, plus abundant storage capacity, easy to recycle, used as electronic products, such as mobile communications, portable computers, etc. The shell structural parts can replace the plastics that are widely used at present, and meet the requirements of lightness, thinness, miniaturization and high integration of electronic products, and are increasingly widely used. In particular, the extensive application of magnesium alloys on automobile bodies can realize the lightweight of automobiles. According to calculations, the weight of the car is reduced by 10%, and its fuel effi...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C23C18/18C23C18/32
Inventor 单大勇周婉秋韩恩厚柯伟
Owner INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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