Method for electrodepositing phosphate/metal composite film on cathode of surface of magnesium alloy

Abstract

The invention relates to a method for electrodepositing phosphate / metal composite film on cathode of surface of magnesium alloy, comprising the following steps: 1) taking magnesium alloy, cleaning surface of the magnesium alloy according to the sequence of mechanically removing dirt, alkaline washing and degreasing, acid washing and activating color temperature, and the cleaning quickly with water; 2) electrifying the magnesium alloy cleaned in step one, and then transferring into phosphate treatment solution to dip with electricity under voltage of 3-5 V, hanging the magnesium alloy on cathode of electrolytic bath, taking zinc as anode, wherein the current density range is between 1 A and 10 A / D2 (ampere / decimeter square), electrifying for 2-10 minutes; 3) taking out the magnesium alloy,blowing with 50-90 DEG C of hot air, forming phosphate / metal composite film on surface of magnesium alloy material, and completing surface treatment of magnesium alloy material. The method of the invention is used to cover phosphate / metal composite film on surface of the magnesium alloy material, and the film has more compact structure than the general phosphating film, thereby having good adhesive force and stronger protection capability; the treatment process has less substrate loss, the treatment solution has wider range, and the solution is convenient to maintain.

Description

Method for Cathodic Electrodeposition of Phosphate / Metal Composite Film on Magnesium Alloy Surface technical field The invention relates to a method for surface treatment of metal materials, in particular to a method for cathodic electrodeposition of a phosphate / metal composite film on the surface of a magnesium alloy. Background technique Magnesium alloys have high specific strength, specific stiffness and good casting, shock absorption, cutting, dimensional stability and excellent electromagnetic shielding properties. However, the surface structure of magnesium alloys is prone to corrosion, and the surface often needs to be treated to increase the protective performance of the magnesium alloy surface. Since the electrochemical potential of magnesium metal is about -2.37v, it is very easy to oxidize in the ordinary atmospheric environment. This layer of oxide film is loose and not firm, which cannot protect the substrate, and hinders the surface treatment of magnesium all...

AI Technical Summary

Problems solved by technology

One is that the microscopic anodes of magnesium alloys cause corrosion deep grooves during the phosphating reaction; the other is that the composition of the solution changes rapidly because of the intense reaction, especially the consumption of hydrogen ions and zinc ions and the accumulation of magnesium ions, which will make batch processing Difficult, not conducive to industrialization promotion