THE ANALYSIS OF THE STRUCTURE OF ELECTROEXPLOSIVE COATINGS OF THE TiC-Ni SYSTEM ON THE DIE STEEL AFTER THE ELECTRON-BEAM TREATMENT

Using the methods of modern physical material science, the authors investigated the phase and elemental composition of the surface layer of Н12MF die steel exposed to the electroexplosive spraying of the TiC-Ni system composite coating and the subsequent irradiation with the high-intensity electron beam of submillisecond exposure time. The scale of the elements of the coating surface structure after the electroexplosive spraying varies in a very wide range – from hundreds of micrometers to tens or hundreds of nanometers. According to the morphological sign, two layers can be identified in the coating volume: a coating as such and a layer of thermal influence smoothly changing into the sample bulk. The subsequent electron-beam treatment of electroexplosive coatings carried out in the melting mode leads to the significant transformation of a relief, the distribution of elements on the coating surface, and the formation of a structurally and concentrically homogeneous surface layer. The surface relief is smoothed out; a relatively uniform gray contrast with the inclusions of rounded particles on the coating surface is replaced predominantly with gray one that indicates the evener distribution of elements along the surface initiated by the treatment. The authors identified the electron-beam processing modes allowing forming dense high-luster surface layers that have a submicrocrystalline structure based on titanium and nickel carbide. The layers enriched and depleted in the titanium carbide are detected as well. However, the concentration of titanium carbide within each layer slightly depends on the distance to the irradiation surface. This fact indicates the formation of a multilayer structure in the material, where the layers with the increased content of titanium carbide (more solid layers) alternate with the layers with the lowered content of titanium carbide (weaker layers).