Electrospark coatings deposited onto an Armco iron substrate with nano- and microstructured WC–Co electrodes: Deposition process, structure, and properties

Nano- and microstructured electrodes WC–8%Co were used for electrospark deposition (ESD) of coatings onto an Armco iron upon variation in the energy P of single discharge pulses between 0.01 and 1.2 J. Considered are the physical and chemical processes taking place at the surface of electrodes: in the coating formed on a substrate (cathode), and in the secondary structure of electrode (anode). The resultant coating was found to contain largely an amorphous phase and tungsten semicarbide W 2C. In case of nanostructured electrodes, an increase in P above some threshold value gives rise to an increasing content of crystalline phases and formation of a structure comprising of sub-micron W 2C/WC grains surrounded by an amorphous binder. In case of microstructured electrodes, the amount of the amorphous phase is predominant for any P. The use of nanostructured electrodes in ESD onto an Armco iron substrates seems expedient only for P < 0.23 J.