Method for preparing composite coating by surface differential arc oxidation/chemical conversion of Mg-Li alloy

A technology of micro-arc oxidation and chemical conversion, applied in anodizing and other directions, can solve the problems of patents and literature reports on the surface of magnesium-lithium alloy surface micro-arc oxidation and micro-arc oxidation/chemical conversion composite coating.

Inactive Publication Date: 2009-04-29
HARBIN ENG UNIV
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  • Application Information

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Problems solved by technology

[0006] According to the latest literature search, there are no patents and literature reports on the research of micro-arc oxidat

Method used

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  • Method for preparing composite coating by surface differential arc oxidation/chemical conversion of Mg-Li alloy
  • Method for preparing composite coating by surface differential arc oxidation/chemical conversion of Mg-Li alloy
  • Method for preparing composite coating by surface differential arc oxidation/chemical conversion of Mg-Li alloy

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Experimental program
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specific Embodiment approach 1

[0029] (1) Pretreatment

[0030] In order to make the micro-arc oxide film have a good bonding force with the substrate, the pretreatment of the Mg-Li alloy surface is an important factor. The requirement of the surface pretreatment of the Mg-Li alloy is to remove the oxide on the surface of the Mg-Li alloy to obtain Clean surface, therefore, the Mg-Li alloy matrix must be surface pretreated before the reaction.

[0031] Combine figure 1 The specific process of pretreatment is:

[0032] Use 240#, 1000#, 2000# sandpaper to polish the Mg-Li alloy in sequence, and then rinse with distilled water; place the polished Mg-Li alloy in an acetone solution, ultrasonically clean for 5 minutes, and rinse with distilled water; finally, rinse and rinse with ethanol. Blow dry.

[0033] (2) Micro arc oxidation

[0034] Place the pre-treated Mg-Li alloy in figure 2 In the electrolyte of the micro-arc oxidation system shown, the composition of the system includes a DC / DC pulse / AC pulse multiplexi...

specific Embodiment approach 2

[0037] (1) Pretreatment of Mg-Li alloy surface

[0038] Carry out the pretreatment of the Mg-Li alloy surface, and immediately carry out the plasma electrolytic oxidation reaction after the pretreatment to avoid oxidation of the treated Mg-Li alloy in contact with air for too long.

[0039] (2) Micro arc oxidation

[0040] The pre-treated Mg-Li alloy is placed in an alkaline silicate electrolyte system; the alloy is subjected to micro-arc oxidation treatment by DC pulse electric output; constant current density: 5A / dm 2 , The output voltage changes continuously during the oxidation process. In this mode, the micro-arc oxidation time is 4 minutes, and the output voltage in the micro-arc oxidation stage is 400V-450V; the Mg-Li alloy sample after the micro-arc oxidation is washed with water and dried with cold air.

[0041] (3) Chemical transformation

[0042] Put the Mg-Li alloy treated by micro-arc oxidation completely into the chemical conversion solution; the reaction temperature...

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Abstract

The invention provides a method for preparing a micro-arc oxidized/chemically converted composite coating on the surface of Mg-Li alloy. The method comprises the following steps: in an electrolyte consisting of 3 to 30 grams of silicate per liter, 1 to 10 grams of sodium hydroxide per liter, 10- 30 milliliters of triethanolamine per liter and 1 to 3 liters of distilled water, pretreated Mg-Li alloy is subjected to micro-arc oxidation for 4 minutes by use of a constant-current micro-arc oxidation mode, at the pulse frequency of 2,000 Hz, with the duty cycle of 15 percent and the current density of 5 A/dm<2>; the Mg-Li alloy subjected to the micro-arc oxidation is completely placed in a chemical conversion solution; the conversion solution consists of 5 to 40 grams of molybdate per liter, 1 to 10 grams of sodium fluoride per liter and 1 to 15 milliliters of hydrogen peroxide with the concentration of 30 percent; the reaction temperature of chemical conversion is 45 DEG C; the reaction time of chemical conversion is 0.5 to 3 hours; and after the chemical conversion treatment, the film-covered Mg-Li alloy is taken out and dried with cold air. The method has the advantages of high efficiency, low cost, simple process and no pollution on environment, and can improve the corrosion resistance of the Mg-Li alloy and widen the application range of the Mg-Li alloy.

Description

(1) Technical field [0001] The invention relates to an alloy surface treatment method, in particular to a preparation method of a Mg-Li alloy surface composite coating. (2) Background technology [0002] Mg-Li alloy is currently the lightest metal structural material (density: 1.30~1.65g / m 3 ), has high specific strength, specific stiffness, better plastic degeneration ability, excellent vibration resistance and resistance to high-energy particle penetration. It has broad application prospects in aviation, aerospace, automobile and electronics. The wide application of Mg-Li alloy can meet the urgent demand for lightweight materials in the aviation, aerospace, automotive and electronics industries, improve energy utilization, reduce environmental pollution, and provide a strong guarantee for the country's sustainable development. It has long-term strategic significance for improving the country's aerospace technology, national defense capabilities, and the level of basic industrie...

Claims

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Application Information

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IPC IPC(8): C25D11/30
Inventor 袁艺卢一景晓燕马春香张密林
Owner HARBIN ENG UNIV
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