Laws of Formation of Electrospark Coatings from Alloys of the Ni – Cr – Al – Y System

The main parameters of electrospark alloying of steel 45 with anodes made from Ni – Cr – Al – Y alloys have been investigated. The anodes were fabricated by casting and hot pressing. The highest values of the mass transfer coefficient were observed in the case of electrospark alloying with hot-pressed alloys. Microstructure and x-ray phase analyses of electrospark coatings revealed the presence of solid solutions based on nickel, iron, chromium as well as intermetallic compounds. Coatings obtained by electrospark alloying with hot-pressed alloy are more wear-resistant than are coatings obtained by alloying with cast alloys.     

Properties of plasma-sprayed coatings treated by laser radiation

The effect of laser treatment on the properties of plasma coatings made from the self-fluxing alloy PGSR-3 with additions of titanium carbide, heat-resistant Ni?Cr?Al?Y alloy, and clad Ni?Al powders was investigated. Laser treatment increased the adherence of the coating to the substrate, density of the surface layers, and promoted the formation of structures with a uniform distribution of alloying elements.     

Temperature dependence of the hardness of dispersion-strengthened molybdenum alloys

Conclusions An analysis of the relationships between the hardness of molybdenum and dispersion-strengthened molybdenum alloys and temperature has shown that these relationships obey an exponential law and represent four distinct regions. In each of them plastic deformation is controlled by a specific mechanism: 1) the overcoming of Peierls-Nabarro barriers, temperature range (0.15–0.2)T_m of molybdenum; 2) motion of newly formed dislocations, (0.2–0.37)T_m; 3) detachment of dislocations from interstitial atoms, (0.37–0.5)T_m; 4) vacancy migration and diffusion along dislocations, (0.5–0.6)T_m.Translated from Poroshkovaya Metallurgiya, No. 6(186), pp. 53–59, June, 1978.     

Properties of wear-resistant coatings of eutectic chromium-carbide alloys

Conclusions The increased hardness and wear resistance of electric-spark coatings compared with thermally sprayed ones is due to the presence of oxide and nitride phases in the alloyed layer, whose phase composition — unlike that of a thermally sprayed layer — is not identical with the starting phase composition. The presence of a secondary structure on the working surface of the electrode in ESA and its role in the formation of the alloyed layer have been established.Translated from Poroshkovaya Metallurgiya, No. 9(261), pp. 42–46, September, 1984.