Study on improving corrosion resistance of AZ31 magnesium alloy by composite film of polydopamine and magnesium hydroxide

As a lightweight and high-strength material, AZ31 magnesium alloy has wide application potential in many fields. However, its corrosion resistance limits its wider application. This study explored an effective method to improve its corrosion resistance by preparing a polydopamine film layer and a composite film layer with magnesium hydroxide on the surface of AZ31 magnesium alloy.

Characteristics of polydopamine film layer

Formation mechanism: Dopamine self-polymerizes in aqueous solution to form a polydopamine film.

Preparation method: A film layer is formed on the surface of AZ31 magnesium alloy by an immersion method.

Performance advantage: The corrosion resistance of magnesium alloy in simulated body fluid is significantly improved.

Magnesium hydroxide composite film layer

Composite effect: Magnesium hydroxide is deposited on the polydopamine film layer to form a composite film layer, which further improves the corrosion resistance.

Preparation technology: Chemical precipitation method is used to deposit magnesium hydroxide on the polydopamine film layer.

Main findings

Improved corrosion resistance: The composite film layer significantly improves the corrosion resistance of AZ31 magnesium alloy.

Surface morphology: The surface of the composite film layer shows a uniform disc-like crystal structure.

Crystallinity and thickness: The film has good crystallinity, a thickness of about 20 μm, and is tightly bonded to the substrate.

Research significance

Application expansion: Provides technical support for the application of AZ31 magnesium alloy in biomedicine and aerospace.

Technological innovation: Provides an innovative magnesium alloy surface treatment technology.

The preparation of polydopamine film layer and its composite film layer with magnesium hydroxide provides an effective way to improve the corrosion resistance of AZ31 magnesium alloy. This method can not only extend the service life of magnesium alloy parts, but also help broaden its application in multiple fields. In addition, the simplicity and ease of implementation of this technology have opened up new directions for magnesium alloy surface treatment.