Electrochemical machining of hard metals – WC/Co as example

Abstract

Electrochemical machining (ECM) is a complex technology used to shape conductive materials, for example hard metals. The workpiece material is removed by anodic dissolution in aqueous electrolytes at extremely large current densities. Hard metals are non-homogeneous and consist of hard particles, e.g. carbides, embedded in a softer matrix formed by metals such as cobalt, nickel, iron or alloys. The final shape is determined by a custom made tool, the cathode, or by a new technique with a confined electrolyte jet (Jet-ECM). An optimisation of this process intents to ascertain detailed information about the influence of current and potential distribution, composition of electrolyte, electrolyte flow geometry, electrochemical behaviour and dissolution mechanism of the components and structure of the interface material/electrolyte. Experiments on WC6Co, a common hard metal consisting of WC particles with Co as a binder, are presented as an example.

Keywords:

• Electrochemical machining
• Jet-ECM
• Hard metals
• Cobalt
• Tungsten carbide
• Anodic dissolution

Acknowledgements

The authors wish to thank the German Research Foundation (DFG) for the financial funds of this project (grant nos. LO 319/16-1, MI 509/16-1, SCHN 745/11-1 and SCHU 1484/7-1) and Ceratizit (Dr R. Useldinger) for providing samples of cemented carbides.