corrosion

Everyday

1. Corrosion is the slow damage of metal or stone by water, air or chemicals, such as iron turning to rust. tree →
2. Corrosion can be any slow wearing away or destruction of something. tree →

In the lessons

In science, corrosion is a chemical change: iron reacts with water and oxygen to form rust; salt water speeds it up, so cars and piers by the sea corrode faster. People stop corrosion with paint, oil, grease or by coating iron with zinc (galvanising). Phrases: «signs of corrosion», «protect against corrosion».

Examples

• Corrosion has eaten holes in the old metal gate. tree →
• Salt on winter roads speeds up corrosion of cars. tree →
• Paint protects the bridge from corrosion. tree →
• In our experiment, the iron nail in salty water showed the most corrosion. tree →
• Gold does not suffer from corrosion, so it stays shiny. tree →
• The battery leaked, and corrosion ruined the remote control. tree →

Note

Uncountable. Verb: corrode; adjective: corrosive (a corrosive acid — safety: these burn skin, so never touch them). Rust is corrosion of iron and steel only; other metals corrode in other colours, like green on copper.