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Magnesium alloy surface conversion coating treating fluid and treating process thereof

A technology of conversion treatment and surface treatment, applied in the direction of metal material coating process, etc., can solve the problems of environmental pollution, non-compliance with environmental protection, etc., and achieve the effect of stable process, easy process control and few additives

Inactive Publication Date: 2010-09-08
JILIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The Dow7 process of Dow Chemical Company in the United States uses sodium chromate and magnesium fluoride to form chromium salts and metal colloids on the surface of magnesium alloys, which have certain corrosion resistance, but hexavalent chromium is a serious carcinogen and causes serious environmental pollution. , does not meet the requirements of environmental protection, the use of chromate has been banned all over the world

Method used

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  • Magnesium alloy surface conversion coating treating fluid and treating process thereof
  • Magnesium alloy surface conversion coating treating fluid and treating process thereof
  • Magnesium alloy surface conversion coating treating fluid and treating process thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0013] The AZ60 magnesium alloy extrusion samples were processed.

[0014] Prepare magnesium alloy treatment solution by following formula:

[0015] Calcium Oxide 1.2 g / liter of aqueous solution

[0016] Phosphoric acid 8ml / liter aqueous solution

[0017] Calcium nitrate 10 grams per liter of aqueous solution

[0018] Sodium m-nitrobenzene sulfonate 1.5 g / liter aqueous solution

[0019] Calcium nitrite 0.8 g / liter aqueous solution

[0020] Degrease the surface of the AZ60 magnesium alloy sample and remove the oxide film, wash it with water, then put it into and immerse it in the above-mentioned prepared treatment solution adjusted to a pH value of 3.2 with phosphoric acid or sodium hydroxide, and let it stand at 40°C for 40 minutes , and then rinse with water, then dry. At this time, after the electrochemical polarization curve test, the self-corrosion voltage increased from the original -1.5mV to -0.89mV, and the self-corrosion current increased from the original 3.2×10 ...

Embodiment 2

[0022] The AZ60 magnesium alloy extrusion sample was processed.

[0023] Prepare magnesium alloy treatment solution by following formula:

[0024] Calcium Oxide 0.8 g / liter aqueous solution

[0025] Phosphoric acid 6ml / liter aqueous solution

[0026] Calcium nitrate 4 grams per liter of aqueous solution

[0027] Sodium m-nitrobenzene sulfonate 0.5 g / liter aqueous solution

[0028] Degrease the surface of the AZ60 magnesium alloy sample and remove the oxide film, wash it with water, then put it into and immerse it in the above-mentioned prepared treatment solution adjusted to PH value of 2.9 with phosphoric acid or sodium hydroxide, and let it stand at 50°C for 30 minutes , then washed with water and dried. After the electrochemical polarization curve test, the self-corrosion voltage increased from -1.49mV to -0.67mV, and the self-corrosion current increased from the original 3.0×10 -3 A / cm 2 up to 2.90×10 -5 A / cm 2 .

[0029] It can be seen from the implementation exam...

Embodiment 3

[0031] The AZ91D magnesium alloy extrusion sample was processed.

[0032] Prepare magnesium alloy treatment solution by following formula:

[0033] Calcium Oxide 0.8 g / liter aqueous solution

[0034] Phosphoric acid 8ml / liter aqueous solution

[0035] Calcium nitrate 8 grams per liter of aqueous solution

[0036] Sodium m-nitrobenzene sulfonate 1.5 g / liter aqueous solution

[0037] Calcium nitrite 0.5 g / liter aqueous solution

[0038] Degrease the surface of the AZ91D magnesium alloy and remove the oxide film, wash it with water, then immerse it in the conversion solution prepared above to adjust the pH value to 3.1 with phosphoric acid or sodium hydroxide, let it stand at 40°C for 30 minutes, and then wash it with water After washing, tumble dry. After the electrochemical polarization curve test, the self-corrosion voltage rose from -1.47mV to -1.22mV, and the self-corrosion current increased from -0.25A / cm 2 up to 6.3×10 -4 A / cm 2 .

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Abstract

The invention provides a magnesium alloy surface conversion coating treating fluid and a treating process thereof. The treating fluid takes water as a solvent, and per liter of the treating fluid has 0.8-1.2g of calcium oxide, 6-10ml of phosphoric acid, 0-11g of accelerator calcium nitride, 0-1.5g of accelerator sodium metanitrobenzene sulfonate and 0-0.8g of solution stabilizer calcium nitrite. The process flow is as follows: degreasing, rinsing, converting, rinsing and drying, wherein the conversion temperature is 30-60 DEG C, and the conversion time is 20-40 min. Due to the treatment process, a delicate and uniform phosphate conversion coating with good protection performance can be formed on the magnetism alloy surface. The treating fluid takes calcium salts as the main component, has the advantages of safety, environment protection and wide application, can be used in independent protection (immersion oil, grease, wax, and the like), and can be used as protection among working procedures and base for organic coatings such as paint, doup and the like. The conversion coating formed by the treating fluid has strong adhesive force and stable components, and can improve anti-corrosion performance of magnetism alloy parts and prolong the service life thereof.

Description

technical field [0001] The invention relates to a magnesium alloy surface anticorrosion treatment technology, in particular to a magnesium alloy surface conversion coating treatment liquid and a treatment process thereof. Background technique [0002] Among metal materials, magnesium alloy has low specific gravity, high specific strength, good electromagnetic shielding, good shock absorption performance and is suitable for recycling. It is increasingly widely used in the aviation industry, automobile industry, home appliance industry, and electronic communication fields. However, the electrode potential of the magnesium alloy is extremely negative (-2.34KV), the chemical stability is poor, and the corrosion resistance is poor. In most media, the magnesium alloy is unstable and easily corroded. To solve the problem of corrosion protection of magnesium alloys, basically start with controlling the content of impurities, prepare high-purity alloys, and form an anti-corrosion fil...

Claims

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Application Information

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IPC IPC(8): C23C22/07
Inventor 李光玉胡晓丽连建设江中浩程仲基孙钰
Owner JILIN UNIV
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