A kind of magnesium alloy fluorine-free electroless nickel plating solution and its nickel plating process

Abstract

A magnesium alloy fluorine-free electroless nickel plating solution and nickel plating process thereof, the nickel plating solution includes an alkaline fluorine-free electroless nickel plating solution and an acidic fluorine-free electroless nickel plating solution; the pH of the alkaline fluorine-free electroless nickel plating solution Value is 10~12, and its composition is: nickel salt, sodium hypophosphite, citrate, sodium carbonate and thiourea; The pH value of described acidic fluorine-free electroless nickel plating solution is 4~6, and its composition is: nickel salt , sodium hypophosphite, citric acid and thiourea. The nickel plating process includes the following steps: polishing, degreasing and degreasing, alkali washing, pickling, activation, alkaline fluorine-free electroless nickel plating, acidic fluorine-free electroless nickel plating, and passivation. The plating solution of the present invention does not contain fluorine, is safe in composition, and does not pollute the environment. The outer layer of the composite coating obtained by nickel plating is an amorphous nickel-phosphorus alloy, and the composite coating has high compactness, good corrosion resistance, good bonding force, and good Industrial application prospects.

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 and environment-friendly electroless nickel-plating solution and a nickel-plating process on a magnesium alloy. Background technique [0002] Magnesium alloys have many unique advantages, such as low density, high specific strength and specific stiffness, and superior damping, machinability, and casting properties. They have been increasingly widely used in the automotive industry, aerospace industry, and electronics 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 solution in order to su...

AI Technical Summary

Problems solved by technology

Fluoride is used in two 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 of CN100476024C, so that the electroless plating speed, the appearance of the coating and the combination of the coating are all unsatisfactory

At present, some people have used alkaline plating solution for magnesium alloys, and have adopted the mode of secondary nickel plating, such as the public scheme of CN103215574A adopts the secondary nickel plating mode of alkaline and neutral nickel plating, but the price is used in the plating solution formula Expensive nickel acetate, added sodium fluoride or potassium fluoride in the alkaline plating solution, added ammonium bifluoride in the neutral plating solution, all introduced fluoride in the plating solution; CN100570000C public scheme adopts alkaline, acidic nickel plating Secondary nickel plating method, but ammonium bifluoride is added to the alkaline and acidic plating solutions, and fluoride is still used in the plating solution, which cannot achieve fluorine-free environmental protection nickel plating, and the corrosion resistance and compactness are not good

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