Definition
A corrosion-protection process for magnesium aircraft parts in which the metal is immersed in a hot sodium dichromate solution. The treatment converts the surface of the magnesium into a chromate film that resists corrosion and provides a base for paint to adhere to.
Plain English
A chemical bath that puts a protective coating on magnesium parts so they don't corrode and so paint sticks to them properly.
Context Anchor
Seen in aircraft maintenance, especially in corrosion-control instructions for magnesium alloy parts.
Derivation
Dichromate refers to a chemical compound containing two chromium atoms bonded with oxygen (from Greek 'di-' meaning two, and 'chroma' meaning color, since chromium compounds are often brightly colored). The treatment is named after the active chemical doing the work.
Why Pilots Care
Maintains the structural strength of airframe components by preventing hidden corrosion damage.
Intuition Check
Dichromate treatment is not simply painting a part. It is a chemical treatment that changes the metal surface enough to help resist corrosion.
Example Sentence 1
The magnesium wheel halves were given a dichromate treatment before painting to protect them from corrosion in service.
Example Sentence 2
The service manual specifies dichromate treatment for all new aluminum fittings prior to installation.