Bronze (Cu+Sn)
Bronze is a copper-tin alloy family with tin content typically 5–12%, often with additions of phosphorus, aluminum, or silicon. Known for superior wear resistance, low friction, and excellent marine corrosion resistance, bronze is essential for bearings, bushings, marine hardware, and artistic casting.
Properties
- Density
- 7,400–8,900 kg/m³
- Melting Point
- 880–1,050 °C
- Boiling Point
- 2,300 °C
- Thermal Conductivity
- 50–75 W/(m·K)
- Electrical Resistivity
- 1.0–1.8 × 10⁻⁷ Ω·m
- Tensile Strength
- 300–900 MPa
- Yield Strength
- 120–550 MPa
- Hardness
- 60–300 HB
- Elongation
- 2–65%
- Crystal Structure
- FCC (α-phase)
Common Grades
- CuSn8 (C52100): Phosphor bronze, 8% Sn. Springs, connectors, bearing elements, fasteners.
- CuAl10Ni5Fe4: Nickel-aluminum bronze. Marine propellers, valves, seawater pumps.
- CuSn12 (C90700): High-tin bearing bronze. Heavy-duty bushings and bearings, worm gears.
- CuSn5Zn5Pb5 (C83600): Leaded red brass / gunmetal. Valves, pump bodies, general castings.
Applications
- Bearings & Bushings: Plain bearings, thrust washers, slide plates, wear strips, guide bushings
- Marine: Ship propellers, seawater valves, underwater fittings, rudder bearings
- Art & Architecture: Sculptures, bells, medals, plaques, decorative castings, church bells
- Industrial: Worm gears, pump impellers, valve bodies, heavy-duty springs
FAQ
Why is bronze used for ship propellers?
Nickel-aluminum bronze (CuAl10Ni5Fe4) combines excellent seawater corrosion resistance, high strength (650+ MPa), good fatigue resistance, and cavitation erosion resistance. It also has anti-biofouling properties and can be repaired by welding — critical for large marine propellers.
What is phosphor bronze used for?
Phosphor bronze (CuSn + 0.2% P) is prized for its combination of strength, fatigue resistance, and low friction. It is the material of choice for electrical connectors, springs, bellows, and precision bearing components where consistent elastic properties are required.
What is the difference between aluminum bronze and tin bronze?
Aluminum bronze (CuAl) contains 5–12% aluminum, providing higher strength (700+ MPa), better corrosion resistance in seawater, and superior high-temperature performance. Tin bronze (CuSn) has lower friction, better bearing properties, and is easier to cast. Aluminum bronze dominates marine; tin bronze dominates bearing applications.