Definition
A method of protecting a metal structure from corrosion by electrically connecting it to a more chemically active (sacrificial) metal, such as zinc or magnesium. The sacrificial metal corrodes in place of the protected structure, because it gives up its electrons more readily.
Plain English
A way to stop metal parts from rusting by attaching a piece of a different metal that will corrode first and take the damage instead.
Context Anchor
Seen in aircraft maintenance and corrosion-control discussions, especially for metal parts exposed to moisture or salt water, such as seaplane floats or metal fittings.
Derivation
From 'cathode,' the negative electrode in an electrical cell. In this protection method, the metal being saved is made into the cathode of the circuit, which is the side that does not corrode. The active metal becomes the anode and is sacrificed.
Why Pilots Care
Aircraft metal structures exposed to water and salt can lose strength through hidden corrosion; cathodic protection extends part life and reduces the risk of structural failure.
Analogy
It is like having a bodyguard made of metal: the bodyguard takes the hits (corrodes) so the protected structure stays intact.
Grounding Statement
On a metal float sitting in salt water, cathodic protection helps keep the float metal from being the part that corrodes first.
Intuition Check
Cathodic protection is not a paint or coating. It protects metal by controlling the electrical corrosion reaction, often by letting another metal corrode instead.
Example Sentence 1
The mechanic replaced the worn zinc anodes on the floats during the seaplane's annual inspection to maintain cathodic protection.
Example Sentence 2
After applying cathodic protection to the belly skin, the inspector noted no further pitting during the next annual inspection.