Metals: Surface Treatments
Design & Technology: AQA GCSE, topic 4.10.1
Surface Treatments
Surface treatments are applied to metals to enhance their properties.
Painting
- Painting provides protection and improves the aesthetics of metals.
- A layer of paint is applied to the metal surface.
- The paint provides corrosion resistance.
- The paint provides a desired colour or finish.
- Primers can be used to improve adhesion.
- Topcoats provide durability and weather resistance.
Plating
- Plating deposits a thin layer of metal onto the surface of a metal substrate.
- Electroplating is a type of plating.
- During electroplating, the metal substrate is immersed in an electrolyte solution with a metal salt.
- An electric current is applied to deposit the desired metal onto the surface.
- Common electroplating metals include chrome, nickel, zinc, and gold.
Anodising
- Anodising is an electrochemical process.
- Anodising is used on aluminium to create a durable and corrosion-resistant oxide layer on its surface.
- The anodised layer can also be dyed to achieve various colours.
Galvanising
- Zinc coating is applied to steel or iron surfaces through a hot-dip galvanising process.
- Galvanisation provides corrosion resistance.
- Galvanisation is used for:
- Structures.
- Automotive components.
- Fasteners.
Powder coating
- Powder coating involves applying a dry powder to a metal surface.
- The metal surface is heated and cured to form a durable and protective coating.
- Powder coating provides:
- Corrosion resistance.
- Impact resistance.
- A range of colours and finishes.
Passivation
- Passivation is a chemical process.
- Passivation is used to improve the corrosion resistance of corrosion-resistant alloys.
- For example, stainless steel.
- Passivation involves treating the metal surface with an acid solution.
- This process removes impurities and creates a passive oxide layer.
Test yourself on Metals: Surface Treatments
What surface treatment deposits a thin layer of metal onto the surface of a metal substrate?
What surface treatment removes impurities and creates a passive oxide layer?