Zinc (Non‑Ferrous Metal)
Overview
Zinc is a non‑ferrous metal mainly used for corrosion protection, alloying, and die casting. In A Level Product Design, zinc is most commonly associated with galvanising steel to prevent rust and with zinc alloys used for mass‑produced components. It is selected for its corrosion resistance, low melting point, and recyclability, rather than strength.
Composition
- Zinc (Zn): Primary element
- Often alloyed with:
- Aluminium
- Copper
- Magnesium
Zinc is rarely used as a structural material on its own due to its low strength.
Physical Properties
- Colour: Bluish‑silver
- Surface finish: Dull when untreated, shiny when polished
- Density: Medium (≈ 7,100 kg/m³)
- Magnetic: No
- Melting point: Low (≈ 420°C)
- Corrosion resistance: Very good
Mechanical Properties
| Property | Description |
|---|---|
| Strength | Low |
| Hardness | Low |
| Ductility | Moderate |
| Malleability | Moderate |
| Toughness | Low |
| Wear resistance | Low |
Working Properties
Advantages
- Low melting point → ideal for die casting
- Excellent corrosion resistance
- Flows well when molten, producing detailed shapes
- Bonds well to steel during galvanising
- Suitable for mass production
Disadvantages
- Weak compared to steel and aluminium
- Can creep (deform slowly under load)
- Limited use as a pure metal
- Brittle at low temperatures
Manufacturing Processes
- Galvanising: Coating steel to prevent corrosion
- Die casting: High‑pressure casting for complex parts
- Alloying: Combined with other metals to improve strength
- Sheet forming: Limited use due to low strength
- Finishing: Polishing, painting, powder coating
Typical Uses
- Galvanised steel products (e.g. fencing, bolts, roofing)
- Die‑cast components (e.g. door handles, locks)
- Car parts
- Electrical components
- Batteries (zinc‑carbon, alkaline)
- Roofing and guttering (sheet zinc)
Corrosion Resistance
- Zinc does not rust
- Acts as a sacrificial metal:
- Corrodes instead of steel
- Protects steel even if scratched
- Ideal for outdoor and exposed environments
Sustainability and Environmental Impact
- Highly recyclable
- Recycling zinc:
- Uses less energy than extraction
- Reduces mining impact
- Galvanising extends the life of steel products
- Long service life reduces material replacement
Health and Safety
- Zinc fumes can be hazardous when heated
- Risk of metal fume fever
- Molten zinc can cause severe burns
- Safe practice includes:
- Good ventilation
- Fume extraction
- Heat‑resistant gloves
- Eye protection
Cost
- Medium cost
- Cheaper than copper
- More expensive than mild steel
- Cost‑effective due to corrosion protection benefits
Suitability for Product Design
Zinc is suitable for: - Corrosion protection (galvanising) - Mass‑produced die‑cast components - Outdoor products - Alloying applications
Zinc is less suitable for: - Structural components - High‑load applications - Lightweight products - High‑temperature environments
Exam Tips (A Level Product Design)
- Identify zinc as a non‑ferrous metal
- Link:
- Galvanising → corrosion protection
- Low melting point → die casting
- Mention:
- Sacrificial protection
- Recyclability
- Compare with:
- Aluminium (lighter, stronger)
- Tin (used for food cans, lower melting point)
- Use key terms: galvanising, sacrificial protection, corrosion‑resistant
Summary
Zinc is a non‑ferrous metal mainly used for corrosion protection and die‑cast components. While it is too weak for structural use, its excellent resistance to corrosion and ability to protect steel make it extremely important in product design and manufacturing. Zinc is best selected for durability, protection, and mass production, rather than strength.