Rusting of materials

Rust consists of iron oxide which is a brownish red substance formed by the reaction of iron exposed to oxygen in the presence of water or air humidity. The rust surface is unstable and brittle.
7.1  Rusting of materials
  • Objects in our environment are made of various materials
  • There are materials that can rust and there are materials that cannot rust
  • Factors that cause rusting 
  1. Presence of water
  2. Presence of air
  • Rusting will not occur if one of these factors is absent
Rusty objects
  • Objects made of iron can rust. 
  • Examples of objects that can rust are iron mailboxes, iron spoons, iron knives.
  • When rusting occurs, the object will turn brownish red, the rusty surface becomes rough and brittle.
  • At some point, the iron turns completely to rust and crumbles.

Importance of preventing objects from rusting
  • Objects will last longer and will not break easily
  • Objects will look clean and pleasant
  • Saves cost as objects do not need to be replaced frequently
  • Objects are safe to use
Ways to prevent rusting
  • Rusting can be avoided by preventing objects made of iron and steel from coming into contact with air and water.
  • The following methods are used to prevent rusting:
  1. Painting
  2. Applying oil or grease
  3. Coating with anti-rust materials such as plastic