Magnesium alloy fluoride-free hydrazine chemical nickel plating solution and nickel plating process thereof

Abstract

The invention discloses a magnesium alloy fluoride-free hydrazine chemical nickel plating solution and a nickel plating process thereof. The nickel plating solution comprises an alkaline fluoride-free hydrazine chemical nickel plating solution and an acidic fluoride-free hydrazine chemical nickel plating solution; the pH value of the alkaline fluoride-free hydrazine chemical nickel plating solution is greater than or equal to 13, and the alkaline fluoride-free hydrazine chemical nickel plating solution consists of nickel chloride, hydrazine, a complexing agent, sodium hydroxide or potassium hydroxide, boric acid or thiourea; the pH value of the acid fluoride-free hydrazine chemical nickel plating solution is 4-6, and the acidic fluoride-free hydrazine chemical nickel plating solution consists of a nickel salt, sodium hypophosphite, citric acid and thiourea. The nickel plating process comprises the following steps: polishing, removing oil and grease, carrying out alkaline washing, pickling, activating, carrying out alkaline fluoride-free hydrazine chemical nickel plating, carrying out acidic fluoride-free hydrazine chemical nickel plating, and passivating. The plating solution is free of fluorine in component, safe in composition, and does not pollute the environment; the service life of the alkaline fluoride-free hydrazine chemical nickel plating solution is long; an outer layer of a composite coating obtained by nickel plating is an amorphous-state nickel phosphorus alloy; and the compact coating is high in compactness, relatively good in corrosion resistance and high in binding force, and has a good industrial application prospect.

Description

technical field [0001] The invention relates to an electroless nickel plating solution and a nickel plating process thereof, in particular to a fluorine-free, environmentally friendly and long-life hydrazine electroless nickel plating solution and a nickel plating process for magnesium alloys. Background technique [0002] Magnesium alloy is known as the green metal structural material in the 21st century. It has many unique advantages, such as low density, high specific strength and specific stiffness, and excellent damping, machinability, and casting performance. It has been widely used in industry. Although magnesium is rich in raw materials and ranks eighth among natural resources, its poor corrosion resistance as a structural material restricts its wider use. [0003] In the electroless nickel plating of magnesium alloys, it is necessary to avoid the strong corrosion reaction and displacement reaction between the magnesium substrate and the components of the plating so...

AI Technical Summary

Problems solved by technology

Fluoride is used in the three commonly used plating solutions, and the existence of fluoride ions not only restricts the material of the plating tank, but also is harmful to the human body and will accelerate the degeneration of teeth. The biggest problem is that fluoride ion wastewater is very Difficult to treat, the cost of wastewater treatment is very high, and it cannot be discharged into the environment in large quantities, otherwise it will cause serious environmental pollution

No buffering agent is added in the alkaline plating solution formula disclosed by CN100476024C, so that the electroless plating speed, the appearance of the coating and the combination of the coating are all unsatisfactory

[0007] At present, some people have used alkaline plating solution for magnesium alloys, and have adopted the mode of secondary nickel plating, such as the disclosed technical scheme of CN103215574A, which adopts the secondary nickel plating mode of alkaline and neutral nickel plating, but in the plating solution formula Expensive nickel acetate is used, sodium fluoride or potassium fluoride are added in the alkaline plating solution, ammonium bifluoride is added in the neutral plating solution, and fluoride is all introduced in the plating solution; the disclosed technical scheme of CN100570000C adopts Alkaline and acidic nickel plating are secondary nickel plating methods, but ammonium bifluoride is added to the alkaline and acidic pl

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