Method for preparing micro-arc oxidation ceramic film layer on surface of magnesium alloy

Abstract

The invention relates to a method for preparing a micro-arc oxidation ceramic film layer on the surface of a magnesium alloy. By controlling the duty cycle and the frequency of a micro-arc oxidation power supply, the pore content and the pore size of the micro-arc oxidation ceramic film layer can be effectively adjusted, and furthermore the hardness of the micro-arc oxidation ceramic film layer is controlled; in addition, the heat in the micro-arc oxidation process can be dissipated through a compressed air stirring system, and a solution is prevented from being partially overheated. The method ensures that the appearance of the micro-arc oxidation ceramic film layer is uniform, continuous and consistent, the hardness of a film layer is controlled to be more than HV400, the salt mist resistance time is longer than 1,000 hours, and meanwhile the binding force of the film layer and a substrate is higher than 40MPa.

Description

technical field [0001] The invention relates to a method for preparing a protective film layer on the surface of a magnesium alloy, in particular to a method for preparing a micro-arc oxidation ceramic film layer on the surface of a magnesium alloy. Background technique [0002] Due to its low density and high specific strength, magnesium alloys are widely used in the aviation field, and a large number of magnesium alloys are used in aero-engine parts. However, due to the active electrochemical properties and low material hardness of magnesium alloys, the parts are prone to electrochemical corrosion and abrasion corrosion during use. At present, the protection methods currently used in China are fluoridation, chromate treatment, etc. Although these traditional surface treatment methods can improve the corrosion resistance of magnesium alloys, the process requirements are strict, and the film layer is relatively thin, poor in density, and not resistant to corrosion. Wear and...

AI Technical Summary

Problems solved by technology

However, due to the active electrochemical properties and low hardness of the magnesium alloy, the parts are prone to electrochemical corrosion and wear corrosion during use.

At present, the protection methods currently used in China are fluoridation, chromate treatment, etc. Although these traditional surface treatment methods can improve the corrosion resistance of magnesium alloys, the process requirements are strict, and the film layer is relatively thin, poor in density, and not resistant to corrosion. Wear and tear; Micro-arc oxidation technology is an advanced surface treatment technology that uses the micro-plasma discharge phenomenon that occurs at the interface between the electrode and the solution to grow a ceramic film on the surface of light metal. The ceramic film prepared by it is both corrosion-resistant and hard. and higher

In aviation products, the technical requirements for this film layer are relatively high, including the surface hardness of magnesium alloys above HV400, the salt spray resistance time of 1000 hours, and the bonding strength with the substrate above 40 MPa. At present, the existing domestic micro-arc oxidation methods cannot meet the above requirements. Require