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UNS C87700 Silicon Bronze

C87700 bronze is a bronze formulated for casting. Cited properties are appropriate for the as-fabricated (no temper or treatment) condition. It has the highest electrical conductivity among cast bronzes. In addition, it has the highest thermal conductivity and a very low ductility.

The graph bars on the material properties cards below compare C87700 bronze to: cast bronzes (top), all copper alloys (middle), and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.

Mechanical Properties

Elastic (Young's, Tensile) Modulus

110 GPa 16 x 106 psi

Elongation at Break

3.6 %

Poisson's Ratio

0.33

Shear Modulus

42 GPa 6.1 x 106 psi

Tensile Strength: Ultimate (UTS)

300 MPa 44 x 103 psi

Tensile Strength: Yield (Proof)

120 MPa 17 x 103 psi

Thermal Properties

Latent Heat of Fusion

250 J/g

Maximum Temperature: Mechanical

180 °C 360 °F

Melting Completion (Liquidus)

980 °C 1800 °F

Melting Onset (Solidus)

900 °C 1650 °F

Specific Heat Capacity

400 J/kg-K 0.1 BTU/lb-°F

Thermal Conductivity

120 W/m-K 68 BTU/h-ft-°F

Thermal Expansion

18 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

45 % IACS

Electrical Conductivity: Equal Weight (Specific)

48 % IACS

Otherwise Unclassified Properties

Base Metal Price

29 % relative

Density

8.5 g/cm3 530 lb/ft3

Embodied Carbon

2.7 kg CO2/kg material

Embodied Energy

45 MJ/kg 19 x 103 BTU/lb

Embodied Water

310 L/kg 37 gal/lb

Common Calculations

Resilience: Ultimate (Unit Rupture Work)

8.6 MJ/m3

Resilience: Unit (Modulus of Resilience)

64 kJ/m3

Stiffness to Weight: Axial

7.4 points

Stiffness to Weight: Bending

19 points

Strength to Weight: Axial

9.8 points

Strength to Weight: Bending

12 points

Thermal Diffusivity

34 mm2/s

Thermal Shock Resistance

11 points

Alloy Composition

Among cast copper alloys, the composition of C87700 bronze is notable for containing a comparatively high amount of silicon (Si) and including manganese (Mn). Silicon is used to improve casting fluidity and lower melting temperature. It also raises strength at the expense of ductility. Manganese is used to improve strength without a proportional reduction in ductility.

Copper (Cu) 87.5 to 90.5
Zinc (Zn) 7.0 to 9.0
Silicon (Si) 2.5 to 3.5
Tin (Sn) 0 to 2.0
Manganese (Mn) 0 to 0.8
Iron (Fe) 0 to 0.5
Nickel (Ni) 0 to 0.25
Phosphorus (P) 0 to 0.15
Antimony (Sb) 0 to 0.1
Lead (Pb) 0 to 0.090
Residuals 0 to 0.8

All values are % weight. Ranges represent what is permitted under applicable standards.

Followup Questions

Similar Alloys

Further Reading

Properties and Selection: Nonferrous Alloys and Special-Purpose Materials, ASM Handbook vol. 2, ASM International, 1993