Casting high-conductivity oxygen-free copper rod from scrap: myths and reality

摘要

To preserve the properties of high conductivity oxygen free-copper rod, the most ductile of all copper grades, special care must be taken when it is produced either entirely from scrap or from a cathode/scrap combination. This presentation describes the effect of some melt pollutants on conductivity and drawability. UPCAST by its own right is not a refining process. In standard cases, the only element that is removed from the melt is oxygen. By some physical and chemical means, and if the system is purposely designed so, some other impurities may be eliminated by oxidation or the addition of additives promoting slag formation, or even mechanically(i.e. hydrogen). However, as oxygen free high conductivity(OFHC) copper rod (UNS C10100 and C10200) becomes the raw material of choice in ever more demanding applications such as high speed multiwire fine and super-fine drawing, ultrafine magnet wire production, among others, the need to produce rod with a consistent excelsior quality crashes with the possibility of using lower quality scrap as raw material. As presented in the title, the focus in this paper is on the most demanding application in terms of scrap use as raw material: high conductivity oxygen-free copper rod (Cu-OFHC). Nevertheless, lesser quality scrap may be "upcast" into products which chemistry and electrical properties are less constraining, as for instance the big family of binary and tertiary brasses, among other products.