Galvanizing of Aircraft Parts

Galvanizing is a process used to protect steel and iron components from corrosion by coating them with a layer of zinc. While galvanizing is commonly used in construction and automotive industries, it is not widely used in aerospace because aircraft primarily use aluminum, titanium, and composites, which do not benefit from traditional galvanizing. However, some ground support equipment (GSE), hangar structures, and certain non-critical aircraft parts may be galvanized for corrosion protection.

Types of Galvanizing

1. Hot-Dip Galvanizing (HDG)

• Process: The steel part is dipped into molten zinc, forming a thick, durable protective coating.
• Advantages: Excellent corrosion protection, long lifespan.
• Limitations in Aerospace: ✔ Not used on aluminum or titanium aircraft components. ✔ The high heat of molten zinc can alter the mechanical properties of aerospace alloys. ✔ The thick zinc layer adds unnecessary weight.

2. Electro-Galvanizing

• Process: Uses electroplating to deposit a thin layer of zinc onto the part.
• Advantages: ✔ Provides moderate corrosion protection. ✔ Thinner and smoother than hot-dip galvanizing.
• Aerospace Applications: Occasionally used for steel fasteners, brackets, and clamps in non-critical areas.
  • Occasionally used for steel fasteners, brackets, and clamps in non-critical areas.

3. Thermal Spray Galvanizing (Zinc Metallizing)

• Process: Zinc is heated and sprayed onto the part’s surface using a plasma or flame spray process.
• Advantages: ✔ Used for corrosion repair of existing coatings. ✔ Provides some protection for steel components in ground support equipment.

Why Galvanizing Is Rare in Aerospace

✖ Aluminum and Titanium Are Naturally Corrosion-Resistant → No need for galvanizing. ✖ Zinc Can Cause Hydrogen Embrittlement → Weakens high-strength steels used in aircraft. ✖ Weight Penalty → Zinc coatings add unnecessary weight to aircraft components. ✖ Other Coatings Perform Better → Aerospace uses alternatives like cadmium plating, anodizing, and zinc-nickel coatings for corrosion resistance.

Aerospace Applications of Galvanizing

✔ Ground Support Equipment (GSE) – Galvanized steel is used in airport infrastructure, maintenance tools, and fuel storage tanks. ✔ Aircraft Hangars & Structural Supports – Protects steel structures from corrosion. ✔ Non-Critical Steel Components – Limited use for brackets, fasteners, and minor fittings.

Alternatives to Galvanizing in Aerospace

Since zinc-based coatings are not ideal for aircraft components, aerospace engineers use:

• Cadmium Plating – Superior corrosion resistance, used on fasteners (being phased out due to environmental concerns).
• Zinc-Nickel Plating – A more aerospace-friendly alternative to cadmium plating.
• Anodizing – Used for aluminum parts to increase corrosion and wear resistance.
• Electroless Nickel Plating – Provides excellent corrosion protection without hydrogen embrittlement risks.
• Ceramic and Fluoropolymer Coatings – Used for high-performance applications.

Industry Standards & Compliance

• AMS 2417 – Zinc-nickel plating for aerospace components.
• MIL-STD-171 – Zinc coatings for military applications.
• ASTM A123 – Standard for hot-dip galvanizing of steel structures (applies to GSE and infrastructure).