What are bronze and gunmetal?
Bronze, derived from the Italian ‘bronzo’, is an alloy of copper and other metals, usually tin. It should not be confused with a copper-zinc alloy, which is generally known as brass or gunmetal. Tin bronze is the best-known alloy. This metal is corrosion-resistant and flexible, but still tough. Adding other alloy components and ingredients to the copper has a significant effect on the properties of the material. A general distinction is made between wrought and cast alloys, depending on the processing method. Typical examples of cast alloys are:
- Tin bronze (8–40% tin)
- Aluminium bronze (5–12% aluminium, 3.5–7% iron)
- Lead bronze (–28% lead)
- Manganese bronze (12% manganese)
- Silicon bronze (1–2% silicon)
- Beryllium bronze/beryllium copper (2% beryllium)
- Phosphor bronze (7% tin, 0.5% phosphor)
- Conductive bronze (magnesium, cadmium, zinc; 3% in total)
- Gunmetal (tin, zinc, lead; 10–20% in total)
- Constantan (40% nickel)
- Nickel silver (45–70% copper, 5–30% nickel, 8–45% zinc)
Where are bronze and gunmetal used?
The various alloys make bronze extremely versatile and suitable for a variety of applications. Depending on the properties required, bronze alloys are used in automotive engineering, shipbuilding and mechanical engineering, but also in the food industry, electrical engineering or in the art world.
- Electronics, electrical engineering (wires, connectors, springs, screws, etc.)
- Machine parts (bearings, propellers, etc.)
- Connectors and joints for pipes
- Construction (doors or door handles)
- Art castings (works of art, sculptures)
- Bell founding
- Musical instruments (percussion)
- Old militaria (guns, shells)
Recycling bronze and gunmetal
In Switzerland, gunmetal is also graded as «bear», «rolled» and «tomba». When recycling bronze and gunmetal, separating the individual reusable materials, particularly any harmful substances, is the most time-consuming part of the process. Only when all the materials have been properly sorted can they be recycled into reusable secondary raw materials and returned to the industrial process.
