Galvanic corrosion is a well-documented electrochemical phenomenon that can silently compromise assemblies, particularly in environments where dissimilar metals are in contact. In industries such as marine, aerospace, construction, and electronics, it represents a persistent reliability risk. It is an issue associated with metal fasteners, so many engineers are using polymer ones to eliminate the issue of premature failure.
What Is Galvanic Corrosion?
Galvanic corrosion occurs when two dissimilar metals are electrically connected in the presence of an electrolyte (such as water, humidity, or salt spray). This creates a galvanic cell:
- One metal acts as the anode (corrodes)
- The other acts as the cathode (protected)
- The electrolyte facilitates ion transfer
The result is accelerated degradation of the anodic material, often leading to premature failure.
Typical Example:
- Stainless steel fastener + aluminium structure + moisture
→Aluminium becomes the anode and corrodes rapidly
The Root Cause: Potential Difference
Each metal has a different position in the galvanic series, which defines its electrochemical potential. The greater the difference between two metals:
- The higher the corrosion risk
- The faster the material degradation
This is why combinations like:
- Aluminium + stainless steel
- Carbon steel + copper
are particularly problematic in conductive environments.
How Polymer Fasteners Eliminate Galvanic Corrosion
The most effective way to prevent galvanic corrosion is to break the electrical circuit. This is where polymer fasteners provide a fundamentally different solution. They completely remove the root cause rather than mitigating symptoms.
Electrical Insulation
High-performance polymers such as: Polyether Ether Ketone, Polytetrafluoroethylene , and Polyamide are inherently non-conductive.
- No electron flow
- No galvanic cell formation
- No corrosion pathway
Chemical Resistance
Polymer fasteners are highly resistant to:
- Saltwater
- Acids and alkalis
- Industrial chemicals
This ensures long-term performance even in aggressive environments where metallic coatings would degrade.
Lightweight and Non-Reactive
Polymers:
- Do not oxidize like metals
- Are significantly lighter
- Do not participate in electrochemical reactions
This makes them particularly valuable in weight-sensitive and corrosion-prone applications.
Barrier Function
Even when used alongside metal components, polymer fasteners act as a physical and electrical barrier, preventing metal-to-metal contact.
Where Polymer Fasteners Make the Biggest Impact
Polymer fasteners are particularly effective in:
- Marine environments (saltwater exposure)
- Aluminium structures (preventing galvanic attack from steel fasteners)
- Electronics and enclosures (electrical isolation required)
- Chemical processing equipment
- Renewable energy systems (e.g. offshore wind)
Galvanic corrosion is not just a material issue but a system-level failure driven by electrical connectivity between dissimilar metals. Traditional mitigation methods, such as coatings or sealants, only delay the problem. Polymer fasteners, by contrast, eliminate the electrochemical pathway entirely.
By leveraging electrically insulating, chemically resistant materials such as PEEK, PTFE, and Nylon, engineers can design assemblies that are inherently immune to galvanic corrosion. The result is improved reliability, reduced maintenance, and longer service life this is particularly in demanding environments where failure is not an option.
In modern engineering, preventing corrosion is no longer about protection; instead, it is about designing it out from the start.