Question

Name the four protective coatings available for aluminum alloys.

Answer 1

The four protective coatings available for aluminum alloys are anodizing, paint or oil coating, chromium coating, and tin coating.

Step-by-step explanation:

The four protective coatings available for aluminum alloys are:

1. Anodizing: This process involves etching the aluminum with sodium hydroxide solution to remove the existing oxide layer and then making the aluminum article the anode in an electrolysis of dilute sulfuric acid. This creates a thick, porous film of oxide on the surface of the aluminum, which can be dyed to add color and increases corrosion resistance.
2. Paint or oil coating: Covering the surface of aluminum with paint or oil prevents corrosion by blocking oxygen contact. However, any scratches or wearing off of the coating can lead to corrosion.
3. Chromium coating: Applying a thin layer of chromium using an electrolytic process forms a protective oxide coating on the aluminum surface, hindering access of oxygen and water.
4. Tin coating: Some aluminum alloys can be coated with a thin layer of tin, which also forms a protective oxide coating that prevents corrosion.