Manage oxygen activity during rod casting
Casted anodes are placed inside large electrolytic cells. By adding electric current, copper dissolves and is eventually deposited on stainless steel ’blanks’. As only copper particles are deposited on the blanks, after 7 days a copper cathode with 99.995% purity is produced. All other elements either sink to the bottom or dissolve in the sulphuric acid. Finally, the produced cathodes are re-melted and cast into eg. copper wire rod.
To produce copper with high performance properties for electrical, electronic and heat transfer applications, it’s imperative to cast copper with extremely low oxygen content of maximum 5 ppm.
Copper grades with higher oxygen content are more likely to react with hydrogen. At high temperature, hydrogen ions can diffuse into copper and create water pores with the oxygen atoms in the copper. This results in more brittle copper, causing problems when copper components are brazed or welded, subsequently affecting physical characteristics of copper, like the electrical and thermal conductivity.
Copper with low oxygen content is more immune to hydrogen and ensures a better joining with brazing or welding methods.
In order to monitor the oxygen content, Heraeus Electro-Nite’s oxygen activity control allows the customer to: