Definition
A soft, silvery-gray metallic chemical element (symbol Ce, atomic number 58) belonging to the rare-earth group. In aviation, cerium is used in alloys, in the manufacture of certain glass and optical coatings, and as a component in catalytic and pyrophoric materials such as the flint used in spark igniters.
Plain English
Cerium is a metal from the rare-earth family. It shows up in aviation in things like spark-producing igniter flints, special glass, and some metal alloys.
Context Anchor
Seen in aircraft materials, maintenance, and metallurgy references when a part or material lists the elements it contains.
Derivation
Named after the dwarf planet Ceres, which had been discovered just two years before cerium was identified in 1803. The name doesn't describe a property of the metal -- it simply commemorates the astronomical discovery of the time.
Why Pilots Care
A pilot is unlikely to use cerium directly in flight, but the term can appear in maintenance information about what a part is made from or why a material behaves a certain way.
Example Sentence 1
The igniter flint contains cerium, which produces sparks when struck.
Example Sentence 2
Mechanics replaced the damaged bracket with a cerium-alloyed magnesium part rated for higher operating temperatures.