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Magnesium alloy surface zinc-calcium series phosphating solution and conversion treatment process thereof

A magnesium alloy and solution technology is applied in the field of zinc-calcium phosphating solution and its conversion treatment process on the surface of magnesium alloy, which can solve the problems of high cost, difficult operation, weak adhesion of protective film and the like, and achieves low cost and high protection. Good performance and strong adhesion

Inactive Publication Date: 2011-02-02
CHONGQING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the above-mentioned solutions for treating the surface of magnesium alloys have disadvantages such as weak adhesion of the protective film, high cost, and difficult operation control. However, there is no report on the zinc-calcium phosphating film

Method used

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  • Magnesium alloy surface zinc-calcium series phosphating solution and conversion treatment process thereof
  • Magnesium alloy surface zinc-calcium series phosphating solution and conversion treatment process thereof
  • Magnesium alloy surface zinc-calcium series phosphating solution and conversion treatment process thereof

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Effect test

Embodiment 1

[0027] Embodiment one: every liter of aqueous solution contains 15 grams of disodium hydrogen phosphate, 4 grams of zinc nitrate, 2 grams of sodium nitrite, 0.5 grams of sodium fluoride, and 0.5 grams of calcium nitrate; and / or sodium hydroxide to adjust the pH.

[0028] Degrease the surface of the magnesium alloy sample and remove the scale (surface activation treatment), wash it with water, and then immerse it in the phosphating solution prepared above to adjust the pH value to 2.5 with phosphoric acid and / or sodium hydroxide. Let stand for 20 minutes, then wash and dry. The film obtained by the present invention is black, and the corrosion current density of the conversion film obtained on the surface of the extruded AZ31 in 3.5% NaCl solution is 23 μA / cm 2 about. The SEM photo of the phosphating film obtained by the present embodiment is shown in the attached figure 1 And the composition analysis of the film layer is shown in the appendix figure 2 .

Embodiment 2

[0029] Embodiment 2: Each liter of aqueous solution contains 20 grams of disodium hydrogen phosphate, 5 grams of zinc nitrate, 3 grams of sodium nitrite, 1 gram of sodium fluoride, and 1 gram of calcium nitrate; the pH value of the phosphating solution is 2.5.

Embodiment 3

[0030] Embodiment three: every liter of aqueous solution contains 30 grams of disodium hydrogen phosphate, 6 grams of zinc nitrate, 4 grams of sodium nitrite, 2 grams of sodium fluoride, and 2 grams of calcium nitrate; the pH value of the phosphating solution is 3.

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Abstract

The invention discloses magnesium alloy surface zinc-calcium series phosphating solution and a conversion treatment process thereof; the magnesium alloy surface phosphating solution is aqueous solution formed by the following constituents, namely, every liter solution contains: 10-30g of disodium hydrogen phosphate, 4-6g of zinc nitrate, 2-4g of sodium nitrite, s0.5-2g of sodium fluoride, and 0.-2g of calcium nitrate; the process for carrying out surface conversion treatment to the phosphating solution comprises the following process flows: alkaline washing and degreasing->rinsing->acidity activation->rinsing->surface activation->rinsing->phosphating->rinsing->drying; the working temperature is 40-70 DEG C, and the time is 5-60 minutes. The conversion treatment process can obtain phosphate conversion coating on the surface of the magnesium alloy, wherein the conversion coating has good protectiveness, is fine and uniform and stable, and has strong adhesive force, and can improve the corrosion-resisting property of magnesium alloy parts; the conversion treatment process is stable and easy to control, and has low cost.

Description

technical field [0001] The invention relates to a magnesium alloy surface anticorrosion treatment technology, in particular to a magnesium alloy surface zinc-calcium phosphating solution and a conversion treatment process thereof. Background technique [0002] Magnesium alloy is the lightest metal material for engineering structures. It has the characteristics of low density, high specific strength, good electrical conductivity and electromagnetic shielding performance, good vibration reduction and damping performance, and easy recycling. Magnesium alloys can be used in automobiles, aerospace, and 3C products (household appliances, computers, communication electronic devices) and other fields. However, the electrode potential of magnesium is very low (-2.37V), its chemical properties are active, and its corrosion resistance is poor. Usually, it can be used only after a protective film is formed on its surface through conversion treatment. [0003] The chromate conversion te...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C23C22/36
Inventor 曾荣昌兰自栋
Owner CHONGQING UNIV OF TECH