Magnesium alloy chromium-free fluorine-free phosphorization solution and phosphorization method

A magnesium alloy and solution technology, applied in the direction of metal material coating process, etc., can solve the problems of poor corrosion resistance, poor corrosion resistance of the film layer, endangering the environment and human health, etc., to improve adhesion, protective performance, and good corrosion resistance. , The effect of high corrosion resistance

Inactive Publication Date: 2010-10-06
NEW MATERIAL INST OF SHANDONG ACADEMY OF SCI
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Problems solved by technology

However, the hexavalent chromium produced by this process is highly toxic and seriously endangers the environment and human health.
[0004] In the chromium-free phosphating process, the main problems are: (1) The phosphating treatment technology contains a large amount of heavy metals such as nickel, lead, nitrite, fluorine, and carcinogens, which do not meet the national requirements for the coating industry. Environmental protection requirements; (2) There are many ingredients (more than 4 kinds) in the phosphating formula, and the influencing factors are complex. Compared with chromate treatment, the corrosion resistance of the film layer is poor, and the corrosion resistance without fluoride is even worse
The Chinese patent with publication number CN 101096761A mentions the formula of magnesium alloy surface phosphating solution, which contains manganese, zinc, fluorine and other substances, and potassium permanganate and zinc dihydrogen phosphate are used, but it contains neither fluoride corrosion resistance nor High; the Chinese patent with publication number CN1598055A mentions the formula of magnesium alloy phosphating solution, which contains corrosion inhibitor sodium fluoride, the existence of fluoride is easy to produce harmful substances to pollute the environment
The literature "Research on Phosphating Process of AZ31 Magnesium Alloy" (Gao Huanfang et al. Surface Technology, 2008, 37(4): 37-39) prepared a corrosion-resistant film on the surface of magnesium alloy AZ31, but the phosphating formula contains nickel, fluorine In addition to nitrite substances, there are more components (9 components), and the corrosion resistance of the film layer is worse than that of chromate treatment

Method used

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  • Magnesium alloy chromium-free fluorine-free phosphorization solution and phosphorization method
  • Magnesium alloy chromium-free fluorine-free phosphorization solution and phosphorization method
  • Magnesium alloy chromium-free fluorine-free phosphorization solution and phosphorization method

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Experimental program
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Effect test

Embodiment 1

[0039] Prepare the phosphating solution according to the following formula:

[0040] Manganese dihydrogen phosphate 40 g / L

[0041] Zinc nitrate 10 g / L

[0042] Citric acid 1 g / L

[0043] Sodium molybdate 1 g / L

[0044] The corrosion resistance of the phosphating film prepared by using the above formula phosphating solution was detected by pitting corrosion of copper sulfate solution. The specific treatment and performance are shown in Table 1.

[0045] Table 1

[0046]

[0047]

[0048] 5% (wt%) NaCl neutral salt spray test (NSS) and adhesion test (cross-hatch method) were carried out on the samples treated above with sprayed and unsprayed amino drying varnish. The test results are shown in Table 2.

[0049] Table 2

[0050]

Embodiment 2

[0052] Prepare the phosphating solution according to the following formula:

[0053] Zinc dihydrogen phosphate 20 g / L

[0054] Manganese nitrate 25 g / L

[0055] Sodium tartrate 3 g / L

[0056] Phytic acid 1 g / L

[0057] The corrosion resistance of the phosphating film prepared by using the above formula phosphating solution was detected by pitting corrosion of copper sulfate solution. The specific treatment and performance are shown in Table 3.

[0058] table 3

[0059]

[0060]

Embodiment 3

[0062] Prepare the phosphating solution according to the following formula:

[0063] Manganese dihydrogen phosphate 15 g / L

[0064] Citric acid 5 g / L

[0065] Sodium molybdate 5 g / L

[0066] The corrosion resistance of the phosphating film prepared by using the above formula phosphating solution was detected by pitting corrosion of copper sulfate solution. The specific treatment and performance are shown in Table 4.

[0067] Table 4

[0068]

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Abstract

The invention relates to magnesium alloy chromium-free fluorine-free phosphorization solution and a phosphorization method. Each liter of the magnesium alloy chromium-free fluorine-free phosphorization solution comprises 1 to 50 g of dihydric phosphate, 0 to 30 g of nitrate and 0.1 to 5 g of additive. The processed magnesium alloy workpiece is soaked and stood in the phosphorization solution of which the pH value is adjusted to be 2.0 to 5.0 by using phosphoric acid and ammonia water and is subjected to phosphating treatment at the temperature of between 30 and 100 DEG C for 1 to 60 minutes to form a phosphate coating. The magnesium alloy is phosphated by the phosphorization solution and the process, a uniform phosphate conversion coating with high corrosion resistance can be obtained on the surface of the magnesium alloy and the phosphate coating can effectively improve the adhesion and the protective property of the subsequent coatings. The phosphorization solution on the surface ofthe magnesium alloy has the advantages of few components and simple preparation. The phosphorization method of the phosphorization solution has the advantages of easy control, stable process, low cost and little sediment.

Description

technical field [0001] The invention relates to a corrosion-resistant chromium-free and fluorine-free phosphating solution formula and a phosphating method on the surface of a magnesium alloy, belonging to the technical field of magnesium alloy surface anticorrosion treatment. Background technique [0002] Magnesium alloy is known as "the most potential and promising green engineering material in the 21st century", and its density is small (1.8g / cm 3 Left and right), high specific strength, large elastic modulus, good shock absorption, and greater impact load capacity than aluminum alloys, it is more and more widely used in aviation, electronic communication, and automotive fields. However, due to the active chemical properties of magnesium, the electrode potential is very low (-2.34KV), resulting in poor corrosion resistance of magnesium alloys, which seriously hinders its promotion and application. Improving the corrosion resistance of magnesium alloys can be achieved by ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C22/42C23C22/18C23C22/13
Inventor 崔学军王修春卢俊峰潘喜庆李庆刚
Owner NEW MATERIAL INST OF SHANDONG ACADEMY OF SCI
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