|
Pure copper is a very ductile metal. For many
applications this is an advantage, but not when copper
is to be machined. However, the cutting properties of
copper can be significantly improved by alloying copper
with half per cent of tellurium. The electrical and
thermal conductivity and ductility of this free machining
copper are only slightly altered.
The effect of tellurium
is based on copper telluride precipitations in the microstructure.
These precipitates have the effect of cutting the chips
into short pieces thus enabling a much higher machining
speed than is possible with pure copper. On a machinability
rating scale with 100 for free cutting brass and 20
for copper, tellurium copper is rated at 90. The tools
last longer too. Tellurium copper is resistant to hydrogen
embrittlement. Electrical conductivity is high, approx.
52 m/W mm2 (90% IACS).
High quality
Tellurium
Good tellurium copper products
can be manufactured only from high quality billets.
It is essential that all free oxygen is eliminated from
the copper by graphite power and CO gas because oxygen
could bind tellurium into an ineffective oxide and it
could make the copper brittle. Another important characteristic
is the distribution of copper telluride particles.
Applications
A typical use of tellurium copper is
the manufacture of gas cutting nozzles which involves
drilling small holes and swaging to the final shape.
For this application we produce tellurium copper rods
of various hardness to suit the customer's manufacturing
process. The high conductivity of tellurium copper makes
it a suitable material for electrical applications.
Many components for electrical switches on power semiconductors,
which require extensive machining, are most economically
produced from tellurium copper.
|