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

A cathodic electrodeposition, metal composite technology, applied in phosphating, electrolytic coatings, coatings, etc., can solve problems such as unfavorable industrialization promotion, batch processing difficulties, etc., to avoid concentrated hydrogen evolution holes, prolong solution life, and low free acid concentration. Effect

Inactive Publication Date: 2010-02-10
CHONGQING UNIVERSITY OF SCIENCE AND TECHNOLOGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] The required treatment solution of the present invention is prepared as follows:

[0024] Take 1.5g of zinc oxide and make a paste with water, dissolve it completely with 4ml of phosphoric acid, and then add the following reagents successively: 0.3g of sodium fluoride, 0.5g of molybdate, 0.1g of sodium dodecylsulfonate, 0.3g of tartaric acid , dilute to 1 liter with water.

[0025] The grade is AZ31 extruded magnesium alloy, and the surface treatment of the magnesium alloy product is carried out according to the following steps:

[0026] 1. Conventional mechanical decontamination: use sandblasting or sandpaper to polish, remove burrs, oxides, extrusion additives, processing oil and other foreign matter, and wash with water;

[0027] 2. Conventional alkali washing and degreasing: wash with 5g / l sodium hydroxide, 10g / l sodium phosphate, 10g / l sodium carbonate, 2g / l surfactant mixed solution, stir at room temperature for 1min; wash with water;

[0028] 3. Routine picklin...

Embodiment 2

[0032] The required treatment solution of the present invention is prepared as follows:

[0033] Phosphoric acid 2.5 ml / L, zinc dihydrogen phosphate 2 g / L, manganese carbonate 3 g / L, sodium fluoride 0.2 g / L, sodium dodecylsulfonate 0.05 g / L, sodium nitrate 0.1 g / L, sub Sodium nitrate 0.4 g / L, citric acid 0.1 g / L. Dissolve the reagents directly in water according to the above sequence to form the desired solution.

[0034] The grade is AZ31 extruded magnesium alloy, and the surface treatment of the magnesium alloy product is carried out according to the following steps:

[0035] 1. Conventional mechanical decontamination: use sandblasting or sandpaper to polish, remove burrs, oxides, extrusion additives, processing oil and other foreign matter, and wash with water;

[0036] 2. Conventional alkali washing and degreasing: wash with 5g / L sodium hydroxide, 10g / L sodium phosphate, 10g / L sodium carbonate, 2g / L surfactant mixed solution, stir at room temperature for 1min; wash with ...

Embodiment 3

[0041] The required treatment solution of the present invention is prepared as follows:

[0042] 2 grams of zinc dihydrogen phosphate, 0.3 grams of nickel nitrate, 0.3 grams of sodium fluoride, 0.2 grams of manganese dihydrogen phosphate, 0.1 grams of sodium dodecylsulfonate, 0.2 grams of sodium nitrate, 0.3 grams of sodium nitrite, 0.1 grams of citric acid , dissolved in 1 liter of water.

[0043] Take the grade as AZ31 extruded magnesium alloy, and follow the steps below to carry out surface treatment on the magnesium alloy product:

[0044] Conventional mechanical decontamination: use sandblasting or sandpaper to remove foreign matter such as burrs, oxides, extrusion additives, processing oil, etc., and wash with water;

[0045] Conventional alkali washing and degreasing: wash with 5g / L sodium hydroxide, 10g / L sodium phosphate, 10g / L sodium carbonate, 2g / L surfactant mixed solution, stir at room temperature for 1min; wash with water;

[0046] Conventional pickling activatio...

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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

technical field [0001] 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 [0002] 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 alloys, hinders Promotion and application of magnesium alloy materials. [0003] At pr...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C25D5/30C25D9/12C25D11/36
Inventor 兰伟
Owner CHONGQING UNIVERSITY OF SCIENCE AND TECHNOLOGY
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