Metallic Lustre and Abrasive Wear of Metals

Metals appear shiny because their pure surfaces reflect light. In air, a thin oxide or contaminant layer forms—rust on iron, copper oxides on copper, aluminium oxide on aluminium, and magnesium oxide on magnesium—making the surface look dull. Rubbing the metal with sandpaper removes this layer, exposing the underlying metallic lustre only where it is scratched.

The simulation models a metal strip divided into a grid of cells, each tracking how much of the dull layer remains. As the sandpaper moves across the strip, the script applies Archard's law, removing material proportionally to the pressure and sliding distance for each cell. Students can watch the progressive removal of the oxide layer and see how the bright regions develop in real time.

By interacting with the model, learners explore concepts of surface chemistry, oxidation, and abrasive wear. They observe how material removal depends on contact pressure and motion, reinforcing the link between microscopic surface processes and the macroscopic property of metallic lustre.