Aluminum is a widely used metal due to its lightweight, corrosion resistance, and strength. However, when aluminum comes into contact with dissimilar metals in the presence of an electrolyte (like water or moisture), it can experience galvanic corrosion.
Understanding how galvanic corrosion occurs and how to prevent it is crucial for engineers, manufacturers, and fabricators working with aluminum in multi-metal applications.
What Is Galvanic Corrosion?
Galvanic corrosion (also called bimetallic corrosion) happens when two different metals are in electrical contact in a conductive environment (such as water, salt spray, or humidity). One metal (the anode) corrodes faster, while the other metal (the cathode) remains protected.
Key Factors That Cause Galvanic Corrosion:
✔ Electrochemical Potential Difference – The greater the difference in reactivity between two metals, the higher the risk of corrosion.
✔ Electrical Contact – The metals must be touching or connected in some way.
✔ Presence of an Electrolyte – Moisture, saltwater, or even industrial pollutants can accelerate corrosion.
💡 Example: If aluminum is in contact with stainless steel in a humid environment, aluminum (the more reactive metal) will corrode faster, while stainless steel remains protected.
How Different Metals Interact with Aluminum
Metals have different levels of reactivity, which determine how likely they are to cause galvanic corrosion when in contact with aluminum.
Here’s a basic galvanic series ranking common metals from most reactive (anodic) to least reactive (cathodic):
Anodic (More Likely to Corrode)Cathodic (Less Likely to Corrode)
MagnesiumGold, Platinum
ZincGraphite, Carbon
AluminumStainless Steel (316, 304)
Steel (Mild, Carbon)Nickel
Copper, Brass, BronzeTitanium
The greater the gap between metals in this table, the higher the risk of galvanic corrosion.
Which Metals Are Most Likely to Cause Corrosion with Aluminum?
🚨 High-Risk Metals (Strong galvanic reaction with aluminum):
Stainless Steel (especially in salty or marine environments)
Copper, Brass, and Bronze (common in plumbing and electrical applications)
Carbon Steel and Iron (corrosion can spread quickly in humid conditions)
✅ Lower-Risk Metals (Minimal galvanic reaction with aluminum):
Zinc (Galvanized Steel) – Often used to protect aluminum through sacrificial coating
Magnesium – Close to aluminum in reactivity, reducing corrosion risk
How to Prevent Galvanic Corrosion Between Aluminum and Other Metals
✅ 1. Use Protective Barriers
Coatings & Paints – Apply anodizing, powder coating, or epoxy coatings to aluminum surfaces.
Sealants – Use non-conductive sealants or gaskets between dissimilar metals.
✅ 2. Avoid Direct Contact
Use plastic, rubber, or nylon washers to separate metals.
Choose insulated fasteners when joining aluminum to steel or copper.
✅ 3. Select Compatible Fasteners
Use aluminum or zinc-coated fasteners instead of stainless steel screws in aluminum structures.
Galvanized or zinc-plated fasteners reduce galvanic reaction.
✅ 4. Control Moisture Exposure
Keep connections dry whenever possible.
Use corrosion-resistant coatings in marine or high-humidity environments.
✅ 5. Apply Cathodic Protection
In marine applications, sacrificial zinc anodes can protect aluminum from corrosion.
Electrical grounding may also help reduce galvanic effects.
Final Thoughts: Protecting Aluminum from Galvanic Corrosion
Galvanic corrosion between aluminum and dissimilar metals can lead to structural failure, increased maintenance costs, and reduced lifespan of materials. By understanding metal compatibility, using protective barriers, and reducing moisture exposure, you can prevent corrosion and extend the durability of aluminum structures.
🔹 Key Takeaways:
✔ Avoid direct contact between aluminum and highly cathodic metals.
✔ Use coatings, sealants, or insulation to separate metals.
✔ Choose fasteners wisely to minimize corrosion risk.
✔ Control environmental exposure to limit moisture and electrolytes.
👉 Need corrosion-resistant solutions for aluminum? Follow these best practices to keep your materials protected! 🔧🔩
