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Free Machining Tellurium Copper
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).
Integrated Production
Good tellurium copper products can be manufactured only from high quality billets. Luvata's production starts from electrolytic refining and goes on to melting and casting the billets for the manufacture of the final semis. It is essential that all free oxygen is eliminated from the copper by adding phosphorus 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. For maximum effect these particles should be small in size and evenly distributed over the whole cross section of the product. We have developed our billet casting process to produce fine and evenly distributed precipitations.
Well equipped laboratories help to maintainthe high standard of prodcut development and expertise. As a result Luvata is able to establish a high level of quality control over its manufacturing process.
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.
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