Formation of WC–Co coating by a novel technique of electrospark granules deposition

• A novel method electrospark deposition of coatings in granules EGD is proposed.
• The method is based on using WC–Co granules from 2 mm in size as an anode.
• The increase in the granules size leads to increases in the cathode gain.
• Mass transfer depends on the ratio of surface areas of substrate and granules.
• The microhardness and wear resistance of the EGD coatings are investigated.

A novel scheme of electrospark deposition of hardening coatings on steel substrate is presented. According to it, the workpiece-substrate which must be coated is placed in the center of a hollow cylinder and filled with granules of WC–Co alloy. The current pulses are passed from the cylinder wall through granules to the cathode. Electrical discharges occur at the points of contact between the hard alloy particles and the cathode surface, and the coating forms on all surfaces of the workpiece simultaneously. This processing configuration is more productive and can facilitate the automation of the electrospark deposition (ESD) of coatings. In this paper, the influence of treatment duration and size of granule fractions on the mass transfer, structure, roughness, microhardness, and wear resistance of the coatings is investigated. It is shown that the obtained coatings have a structure and properties similar to those of traditional electrospark WC–Co coatings.

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