Magnesium alloy with zinc and nickel compound plating layers and preparation method thereof

Abstract

The invention discloses a magnesium alloy with zinc and nickel compound plating layers and a preparation method thereof. A zinc plating layer of the magnesium alloy is taken as a bottom layer with the width between 20 microns and 25 microns, a nickel plating layer is taken as a surface layer, and the total width of the zinc plating layer and the nickel plating layer is less than or equal to 40 microns. The method comprises the following steps: firstly, plating preliminary treatment, i.e. zinc is activated in an acid solution and then soaked in sulphate; secondly, zinc electrodeposition, i.e. after the zinc is soaked in the sulphate in the first step, the zinc layer of the magnesium alloy is electrodeposited; thirdly, nickel bright plating, i.e. the magnesium alloy which is nicely processed in the second step is brightly plated with nickel in a nickel plating solution; fourthly, sodium silicate water solution sealing. With the method, the obtained zinc plating layer is nicely combined with a base body, has uniform width and high corrosion resistance, can be taken as a protective plating layer to be singly used and can be also taken as a transition layer to carry out plating or chemical plating or other protective or decorative platings, and the nickel plating layer obtained from the zinc plating layer by plating is nicely combined with the zinc plating layer and is uniform, exquisite, bright and beautiful.

Description

technical field [0001] The invention relates to a method for electroplating zinc and nickel composite coatings on magnesium alloys, belonging to the technical field of metal corrosion and protection. Background technique [0002] Due to its small specific gravity, high electrical and thermal conductivity, good shock resistance, and good processing performance, magnesium alloys are widely used in electronic and electrical industries such as automobiles, motorcycles, computers, communications, instrumentation, home appliances, light industry, chemical industry, and metallurgy. , Aerospace, national defense and other sectors have been more widely used. In the past ten years, the market share of die-casting magnesium alloys has been growing rapidly at an annual rate of about 18%. It is estimated that by 2010, the output of magnesium alloys will reach 850,000 tons. [0003] The use of magnesium alloys as structural materials has broad prospects. However, so far, the application ...

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Problems solved by technology

[0005] At present, electroless nickel plating is the most researched metal coating on magnesium alloys. Generally, basic nickel carbonate or nickel acetate is used as the main salt. However, due to the high chemical activity of magnesium alloys, strong corrosion and replacement will occur after entering the electroless nickel plating solution. reaction, accompanied by a large amount of hydrogen evolution, resulting in poor bonding between the deposited nickel coating and the magnesium alloy substrate, local blistering or convex peeling, these defects cannot guarantee the high corrosion resistance of the coating, and it is difficult to achieve a satisfactory protective effect