Magnesium

Magnesium anodizing forms a hard oxide/ceramic-like conversion layer on magnesium alloys to boost corrosion resistance, paint adhesion, and electrical insulation.

Overview

Magnesium anodizing is an electrochemical surface treatment that converts the outer surface of magnesium into a protective oxide/ceramic-like layer (common specs include HAE, Dow 17, and proprietary processes). It’s used to control rapid corrosion, improve wear resistance versus bare Mg, and provide a stable base for primer/paint or powder coat.

Choose it for lightweight magnesium parts that will see humidity, salt exposure, handling, or where you need better electrical insulation and adhesion than chemical conversion alone. Tradeoffs: cosmetic appearance is usually matte/gray and can vary by alloy and casting quality; thickness and porosity require sealing and often a topcoat for harsh environments. Not all magnesium alloys anodize equally, and process availability is narrower than aluminum, so lead times and spec compliance can drive cost.

Common Materials

  • AZ31B
  • AZ91D
  • AM60B
  • WE43
  • Elektron 21

Tolerances

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Applications

  • Aerospace gearbox housings
  • UAV airframe brackets
  • Handheld electronics housings
  • Camera gimbal components
  • Motorsport transmission covers
  • Medical device chassis

When to Choose Magnesium

Use magnesium anodizing on Mg parts that must survive corrosion exposure while staying lightweight, especially when you need a robust base for paint or powder coat. It fits low-to-medium volumes where performance and reliability matter more than purely cosmetic finish. It’s most effective when the design allows masking and post-seal/topcoat requirements.

vs Aluminum

Choose magnesium anodizing when mass reduction is driving the design and you’re already committed to Mg alloys. The anodize layer primarily enables corrosion control and coating adhesion on magnesium rather than the broad decorative/functional finish options typical on aluminum.

vs Titanium

Choose magnesium anodizing when you need the lightest structural metal and the service environment can be managed with sealing and topcoat systems. Titanium anodizing is often selected for color ID and naturally strong corrosion resistance; magnesium anodizing is more about making a corrosion-prone substrate viable.

vs Zinc

Choose magnesium anodizing for lightweight structural parts where zinc’s density and typical use as plating/coating doesn’t meet weight targets. Zinc finishes are commonly used for fasteners and steel protection; magnesium anodizing targets base-magnesium parts that need a protective/paintable surface.

vs Niobium

Choose magnesium anodizing when the requirement is lightweight mechanical hardware rather than specialized biomedical/electronic applications. Niobium anodizing is typically driven by stable oxide behavior and coloration; magnesium anodizing is driven by corrosion mitigation on Mg alloys.

vs Tantalum

Choose magnesium anodizing for weight-sensitive housings and brackets where cost and machinability matter. Tantalum anodizing is usually tied to extreme corrosion resistance and capacitor/chemical environments; magnesium anodizing addresses everyday corrosion challenges on Mg substrates with sealing/topcoat systems.

Design Considerations

  • Call out the exact process/spec (e.g., HAE, Dow 17, MIL/AMS) plus sealing requirements and any paint/powder topcoat
  • Mask critical fits, threads, and ground points; specify allowable contact marks from racking
  • Avoid sharp edges and thin fins where coating can thin out or burn; add small edge breaks and uniform wall sections
  • Select anodize-compatible magnesium alloys early; some cast alloys and high-impurity lots show appearance and corrosion variability
  • Specify target coating thickness (or performance requirement like salt spray) and whether dimensional change is acceptable
  • Control galvanic couples in the assembly (isolation washers, primers) because anodize damage exposes highly active magnesium