What is Plating?

This has long history and in Japan, gold-plating (Amalgam Method) of “ Great Buddha of Nara” is famous. Then, why is it necessary?

The followings are effects for plating.
*For fine appearance of the materials.
*For rust and corrosion resistance of the materials such as iron.
*For good conductivity
*For anti-abrasion
*For improvement of sliding,　 etc.

This shows the reaction below.

First, we describe the principle called ionization tendency, which shows oxidizing (rusting) rate.
(See right figure.)
Metals with higher tendency oxidize faster than those with lower.

We explain Zn plating using the tendency.

When the Zn plated surface is scratched,, the uncovered part is expected to rust. However, only Zn plated parts rust. According to the tendency, the phenomenon Zn rusts faster than iron can prevent iron from rusting , which is called sacrificial protection.