Application of the Technology of Electrospark Deposition and Modified SHS-Electrode Materials to Improve the Resistance of Hot Rolling Mill Rolls. 1. Features of the Formation of Coatings on Substrates of SPHN-60 White Iron

The electrospark deposition on samples made of white cast iron SPHN-60 was carried out in two stages. At the first stage, a barrier sublayer was applied, on the second stage – a multifunctional protective coating. Two materials for the electrodes, Ni and Cr, were chosen to form a sublayer according to calculations of Palatnik's criterion. The impact of a sublayer on the features of the formation of electrospark coatings was studied using hard-metal electrodes of STIM-40НАОКн (TiC – NiAl + ZrO₂^nano) and STIM-11ОКн (TiB₂ – NiAl + ZrO₂^nano). The phase composition and the surface roughness of the formed coatings were studied. It is found that deposition of a sublayer contributes to an increase in the fraction of refractory phases in coatings. The surface roughness varied from 3.37 to 8.20 μm. The adhesion strength of two-layer electrospark coatings to the substrate exceeds 100 N.