A kind of am50a die-casting magnesium alloy with excellent corrosion resistance oxide film and its preparation method

Abstract

The invention relates to an AM50A die-casting magnesium alloy with excellent corrosion resistance oxide film and a preparation method thereof, belonging to the technical field of magnesium alloy preparation. The present invention sprays a release agent with a certain thickness on the mold during high-temperature die-casting, so that it reacts with the alloy melt to generate a uniform corrosion-resistant oxide film on the surface of the magnesium-manganese alloy AM50A (the composition of the oxide film is Al: 1.97~5.21at.%, Si: 11.54~16.99at.%, C: 14.7~14.92at.%, Ca: 0.94~1.33at.%, O: 39.93~54.16at.%, Mn: 0.07~0.08at.% %, the rest is Mg), this oxide film can greatly improve the corrosion resistance of AM50A die-casting magnesium alloy, slow down the corrosion rate, and further expand its application in industry on a large scale.

Description

technical field [0001] The invention belongs to the technical field of magnesium alloy material preparation, and in particular relates to an AM50A die-casting magnesium alloy with an excellent corrosion-resistant oxide film and a preparation method thereof. Background technique [0002] As the lightest metal structural material, magnesium alloy is widely used in the fields of automobile and aerospace due to its high specific strength and specific stiffness, excellent damping, shock absorption, noise reduction and cutting performance. However, due to the relatively active chemical properties of magnesium alloys, it is easy to react with oxygen in the air to form a loose and porous oxide film, which cannot protect the magnesium substrate from continuous corrosion, making the corrosion resistance of the alloy, especially in humid environments Corrosion resistance is poor, which limits its wide application to some extent. [0003] In order to solve the problem of poor corrosion...

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Problems solved by technology

Surface coating treatment is beneficial to improve the corrosion resistance of magnesium alloys, but the coating is generally thin (<1μm), has poor mechanical properties, weak binding ability with the body, and is easy to fall off. It can only be used to protect the metal for a short time and cannot be used For long-term protective coatings; chemical conversion coatings have good protective properties, among which chromate conversion coatings have the best anti-corrosion effect, but the existence of chromium compounds causes subsequent processing difficulties and environmental pollution problems, while chromium-free conversion coatings The biggest disadvantage is that the film layer is not dense enough, the film is thin, the protection performance is poor, and it cannot heal itself after damage; the corrosion resistance, wear resistance and hardness of the anodized film are generally higher than the chemical conversion film, but the disadvantage of this method is that It is difficult to obtain a uniform film layer for complex components, and the film is relatively brittle. However, the micro-arc oxidation developed on the basis of it requires large equipment investment and high energy consumption, which limits its application.

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