Definition
A chemical solution containing dichromate salts (typically sodium or potassium dichromate) used to chemically treat aluminum and magnesium aircraft parts. The solution forms a protective oxide film on the metal surface that resists corrosion and provides a good base for paint adhesion.
Plain English
A chemical bath used to coat aluminum and magnesium parts so they don't corrode and so paint sticks to them properly.
Context Anchor
Seen in aircraft maintenance and corrosion-control procedures, especially when treating magnesium alloy parts.
Derivation
Dichromate comes from 'di-' (two) and 'chromate' (a salt of chromic acid, from Greek 'chroma' meaning color). Chromium compounds were named for the brilliant colors they produce. The 'di' indicates the chemical structure contains two chromium atoms per molecule.
Why Pilots Care
Corrosion is one of the most common reasons aluminum and magnesium parts are condemned during inspection. Treatments like dichromate solution extend the service life of airframe components and are part of why aircraft can remain airworthy for decades.
Intuition Check
Do not read “solution” here as just any helpful liquid or cleaner. In this context, dichromate solution is a specific chemical treatment used for corrosion protection, not a general wash or soap.
Example Sentence 1
After cleaning the magnesium wheel halves, the mechanic dipped them in a dichromate solution to protect them from corrosion before painting.
Example Sentence 2
The mechanic applied dichromate solution to the repaired aluminum bracket before reinstallation.