Processes and properties of deposits in electrospark deposition

In the electrospark deposition of a material, a high current is conducted through an oscillating electrode and a substrate for a very short period of time. When the electrode is moved away from the surface, an arc is formed momentarily, causing melting of the electrode surface for a short time. In the present work, the process was monitored in real time using a high speed camera, permitting determination of the mode of mass transfer from the electrode to the substrate, the number and size of droplets, and arc guidance (i.e. spark guidance in the present process) during deposition. The variations of welding current, welding voltage, and pulse frequency were analysed using a high performance oscilloscope. One of the applications of the process is the deposition of hard layers on die casting tools for aluminium. The analysis was carried out using a scanning electron microscope and an X-ray diffraction microanalyser. Energy input was also studied.