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.
| Cu | 87.5 to 90.5 | |
| Zn | 7.0 to 9.0 | |
| Si | 2.5 to 3.5 | |
| Sn | 0 to 2.0 | |
| Mn | 0 to 0.8 | |
| Fe | 0 to 0.5 | |
| Ni | 0 to 0.25 | |
| P | 0 to 0.15 | |
| Sb | 0 to 0.1 | |
| Pb | 0 to 0.090 | |
| res. | 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