A method of preparing oxide film on the surface of magnesium alloy by micro-arc oxidation

Abstract

The invention provides a method of preparing an oxidation film on the surface of a magnesium alloy by utilizing micro-arc oxidation. The method comprises the following steps that the magnesium alloy is placed into an electrolytic tank filled with an alkaline electrolyte, the magnesium alloy serves as an electrolytic anode, the electrolytic tank serves as an electrolytic cathode, voltage is appliedto allow plasma discharge to be generated on the magnesium alloy, the oxidation film is formed on the surface of the magnesium alloy by utilizing the micro-arc oxidation, and the components of the alkaline electrolyte are 8-12 g / L of NaOH, 10-15 g / L of Na2SiO3, 6-8 g / L of KF, 2-3 mL / L of H2O2, 6-8 mL / L of glycerol, 1-2 g / L of sodium ethylenediamine teramethylene phosphonate and the balance water;and in the micro-arc oxidation process, zeolite powder and gamma-aluminum oxide nano micropowder are sequentially added into the electrolyte, and a micro-arc oxidation reaction is continued to be carried out until the preparation of the oxidation film is completed. The reaction process of the micro-arc oxidation is affected through the synthetic action of the components, the amount of microporeson the surface layer of the oxidation film is reduced, the compactness of the oxidation film is improved basically, and the corrosion-resistant performance is strengthened.

Description

technical field [0001] The invention relates to a processing method of a magnesium alloy, in particular to a method for preparing an oxide film on the surface of a magnesium alloy by micro-arc oxidation. Background technique [0002] Magnesium and magnesium alloys have the characteristics of low density, high specific strength and specific stiffness, good casting, welding, damping, cutting and dimensional stability, and are the most potential metals for lightweight, environmental protection and performance optimization. Structural materials are also one of the most promising metal materials in the 21st century. Since magnesium is a relatively active metal, magnesium and magnesium alloys are extremely prone to corrosion during its application, and its poor corrosion resistance severely limits their application in various fields. Therefore, the surface modification of magnesium and magnesium alloys become a research hotspot in recent years. [0003] Micro-arc oxidation is a ...

AI Technical Summary

Problems solved by technology

The practical application of phosphate is limited due to the different degrees of harm to the human body and the environment.

The silicate system has a higher film forming rate, and the resulting film has excellent hardness and wear resistance, but its corrosion resistance is slightly worse than that of the phosphate system

The film layer obtained by the aluminate system has better wear resistance, and the bonding force between the film and the substrate is relatively better, but the film forming speed and corrosion resistance are poor.

[0005] However, no matter which electrolyte is used, due to the micro-arc oxidation mechanism, during the formation of the oxide film, the initial oxide film is continuously broken down, and the resulting instantaneous high temperature causes a large amount of water vapor to be generated at the interface between the film layer and the solution. At the same time, the surface layer of the high-temperature melt is in direct contact with the solution and solidifies before the inner layer, so that the escape channel of the internal gas is closed, and the gas that is too late to escape escapes when the oxide film is broken down next time, forming holes.

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