Formation processes, structure, and properties of spark coatings of armco iron obtained with the use of nanostructured and microstructured WC-Co electrodes

Abstract

Nanostructured and microstructured electrode materials of the composition 92%WC-8%Co were used for deposition of spark coatings on Armco iron upon variation in the energy of pulsed discharges in the range from 0.01 to 1.2 J. Physicochemical processes on contact surfaces are considered during operation by both types of electrode pairs, namely, in the forming coating of the cathode substrate and in the secondary structure of the anode electrode. It is found that the main phases in coatings are the amorphous phase and tungsten semicarbide W2C. In the case of a nanostructured electrode, an increase in the energy mode above a certain threshold value leads to an increase in the fraction of crystalline phases and to the formation of a structure consisting of submicron W2C/WC grains surrounded by an amorphous binder. With the use of a microstructured electrode, the fraction of the amorphous phase in coatings prevails in all energy modes. The use of nanostructured electrodes in the technology of spark treatment of substrates made from Armco iron is expedient only at a pulse energy of <0.23 J.