C109 / CW118C /Tellurium Copper

C109 / CW118C is a free machining tellurium containing alloy that retains the high conductivity values associated with pure copper. The machining characteristics of the copper are significantly improved by alloying it with approximately half per cent of tellurium, while the electrical and thermal conductivity are only slightly reduced.

The tellurium forms a small precipitate that is evenly distributed throughout the microstructure and acts as a chip breaker causing the swarf to break into short pieces. The alloy offers a machinability rating of ~90% (free cutting brass = 100) versus a standard copper machinability rating of ~20%. This allows the C109 / CW118C to be machined at a much higher speed with lower tool wear, giving machinists and designers a more cost effective product.

Tellurium copper is manufactured by refining, melting and casting the material in to billets for the manufacture of the final product. It is essential that any oxygen is eliminated at this stage to give a resistance to hydrogen embrittlement and prevent any oxygen combining with tellurium that would make the copper brittle.

Chemical Composition

Copper

Rem

Tellurium

0.4–0.7%

Phosphorus

0.003-0.012%

Total Imps

0.1% max

Related Specifications

C109

C14500

CW118C

CuTe

DIN 2.1546

 

Key Features

  • Excellent Electrical Conductivity
  • Free Machinability
  • Freedom from Hydrogen Embrittlement
  • Very Good thermal conductivity

Typical Physical Properties

Melting Point

1081°C

Density

8.9 g/cm³

Specific heat

385 J/Kg °K

Thermal conductivity

370 W/m°C

Thermal expansion coefficient  (20-200°C)

17.0 x 10-6

Electrical conductivity

94 % IACS

Electrical resistivity

0.0187 microhm m

Modulus of elasticity

12500 Kg/mm²

Fabrication Properties

Hot Working Temperature Range

725-825°C

Hot Formability

Good

Cold Formability

Good

Cold reduction between anneals

70% max.

Machinability rating (free cutting brass = 100)

85-90%

Joining Methods

Soldering

Excellent

Brazing

Good

Oxy-acetylene welding

Not Recommended

Gas-shielded arc welding

Fair

Resistance welding:        Spot and Seam

                                    Butt

Not recommended

 

Fair

Typical Uses:

Traditional uses for C109 / CW118C Tellurium Copper are electrical components that require extensive or intricate machining including electrical switches for power semi-conductors, transformer and circuit breaker terminals, gas cutting nozzles, contacts, clamps, electrical connector pins, bolts, nuts, studs and other components requiring free machinability.

This technical information is given by John Hood & Co.without charge and the user shall employ such information at their own discretion and risk. For more detailed technical advice on temper selection, fabrication, joining, machining, physical and mechanical data please contact us as space does not permit the listing of every feature of the material.