When Metals Whisper: A Quiet Story of Corrosion
There is a quiet conversation that happens between metals.
Two surfaces meet— nothing dramatic, nothing visible at first. Just contact.
But beneath that stillness, something begins to move.
The unseen difference
Not all metals are the same.
Some are willing to let go— to release their electrons without resistance. Others hold on tightly, reluctant to give anything away.
When these two meet, a difference is created. A small imbalance. A quiet tension.
When water enters the story
Moisture does not force the reaction— it simply allows it to continue.
Like a bridge, it carries ions, completing a path that was waiting to exist.
Electrons begin to flow— not through the water, but through the metals themselves.
And just like that, a tiny battery is born.
The sacrifice
One metal gives.
It becomes the anode— losing electrons, dissolving slowly into the environment.
The other receives.
It becomes the cathode— protected, unchanged, quietly preserved.
No noise. No warning.
Just a slow exchange— one fading so the other remains.
A truth engineers know
This is not just decay. It is a principle.
One that engineers use deliberately— choosing a metal to sacrifice so that something greater can endure.
Final reflection
When metals touch in the presence of water, they do not simply coexist— one begins to give, so the other may last.
When Metals Touch: Understanding Galvanic Corrosion What is galvanic corrosion?
Galvanic corrosion is an electrochemical process that occurs when two dissimilar metals are in electrical contact in the presence of an electrolyte, such as water.
Why does it occur?
Different metals have different tendencies to lose electrons. When they are connected, this difference creates a potential difference, similar to a small electrochemical cell.
In the presence of moisture:
Electrons flow through the metal from the more active metal to the less active metal
Ions move through the electrolyte, completing the circuit
This allows the corrosion process to continue.
What happens during corrosion?
The anode (more active metal) loses electrons and corrodes
The cathode (less active metal) gains electrons and is protected
At the anode, metal atoms dissolve into ions, leading to material loss.
Real-world applications
Galvanic corrosion is commonly observed in:
Coastal and marine structures
Fasteners connecting dissimilar metals
Pipelines and electrical systems
This principle is also used intentionally in cathodic protection, where a sacrificial metal (such as zinc) corrodes to protect more critical components.
Key takeaway
Dissimilar metals in contact with an electrolyte form an electrochemical system that drives corrosion of the more active metal.