Properties of Metal & Painting of Metals

Lesson Objectives

• Learn about the properties of metals, painting, galvanising, and electroplating metals.

Introduction

Most everyday items are processed to enhance longevity or change characteristics. For instance, cars involve various inputs such as people, money, material, knowledge, tools, energy, and time in their processing.

Properties of Metals

Metals are valuable in manufacturing due to their properties:

• Durability: Strong and long-lasting.

• Flexibility: Can be melted and molded.

• Conductivity: Can conduct heat and electricity.

• Stretchability: Can be drawn into wires and tubes.

• Forgeability: Can be reshaped through forging.

These properties can be enhanced through preservation methods such as painting, galvanising, and electroplating.

Painting Metals

Finishing improves appearance and resistance to weather, insects, heat, liquids, fungi, and dirt. Painting is a method to prevent rust on iron-containing metals. Steps for painting include:

1. Clean the metal surface.

2. Smooth the surface if necessary.

3. Apply a primer coat.

4. Once dry, apply the enamel coat or spray paint for a smoother finish.

Preservation

Galvanising of Metals

Galvanising involves immersing iron or steel in boiling, melted zinc to create a protective zinc layer that prevents rusting through a chemical reaction. As a result, galvanised iron/steel resists rust even in air and moisture.

Reasons:

• Prevents rust

• Enhances strength

• Improves appearance

Examples:Support beams, pipes, handrails, light fittings, beds, baths, buckets.

Electroplating of Metals

Electroplating applies a thin, smooth protective layer of one metal onto another, providing physical protection against water and air. However, if scratched, the underlying metal can rust.

Reasons for Use:

• Improves appearance

• Increases electrical conductivity

• Protects against corrosion and rust

Examples:Cutlery, decorative items, jewelry (gold/silver plating), chrome on copper (for corrosion resistance), nickel/chrome/tin/zinc on iron/steel, and zinc-plated steel screws for longevity.