Effect of the Nature of Electrode Materials on Erosion and Properties of Doped Layers. The Criteria for Evaluating the Effectiveness of Electrospark Alloying

Abstract

Introduction. The method of electrospark alloying of metal surfaces was proposed by the Russian scientists B. R. Lazarenko and N. I. Lazarenko. It is possible to apply this process to the surface of the workpiece from any conductive materials of a hardened alloyed layer of material to ensure high hardness, heat resistance, wear resistance and other properties of the executive surfaces of the parts. The paper shows the possibility of formulating criteria for determining the efficiency of the electrospark alloying process and the properties of the doped layer, depending on the properties of d-elements determined by their position in the periodic table and a number of (s+d)-electrons of electrode materials. A similar approach to determining performance criteria can be recommended for other high-energy materials exposure processes. Materials and Мethods. The authors used steel 45 as the material of the rim sections and refractory d-metals of IV-VI groups: Ti, V, Cr, Zr, Nb, Vo, Hf, Ta, W; а также d-metals: Mn, Fe, Co, Ni, Cu, Zn, Pd, Ag, Cd, Re, Os, Ir, Pt, Au and p-metals: Al, Bi, Sb, Sn, Pb as anode materials for creating doped layers. The installations used for electric-spark alloying: EFI-10M, EFI-46A, EFI-25M, EFI-66, Electrom-10, ELFA-541, Elitron-22, IMEI-01-2A; Corona- 1101; microscope MII-4, MIM-10, BIOLAM-M, EMA-100, Axiosplan-2; Profiler P-201 “Caliber”; microthermometry PMT-3M, DUH-W201, Shimadzu. In the study of erosion there we used the installation of “Atovic absorption spectrophotometer, Varian AA-4”. The generator GOS-3OM and installation SLS-10-1 wer used for laser processing. Results. The generalization of the schemes of the process of electric-spark alloying in single and repeated exposure of the model anode material was made. At the cathode there is a hole with a different degree of filling of the cathode material or representing the zone of mutual crystallization of the anode material and the cathode. When exposed to spark discharge in a gaseous medium, there are differences in the formation of holes due to the more intense transfer of eroded material to the opposite electrode, especially to the cathode. Dependences of some properties (microhardness, melting point, elastic modulus) of refractory d-metals on their location in the IV–VI periods of the periodic table are obtained and presented. Dimensional and volumetric relations of d-elements in electrospark alloying were established, depending on their location in the periodic table. Dependences of the properties of model electrode materials on the statistical weight of atomic stable configurations, as well as the dependence of the erosion of the anode of transition metals on the number (s+d)- electrons and the interelectrode medium. The patterns of d-metals erosion under electrospark alloying and other types of high-energy impact to the surface have been found. Conclusions. Based on the results of this research, it can be stated that in order to achieve higher coating properties and greater efficiency of electrospark alloying, it is necessary to give preference to anodic materials having the maximum statistical weight of atomic stable configurations. It can be said that the properties of the electrode materials relate to their erosion amount and the parameters of the efficiency for forming the doped layer during electrospark alloying, which for specific conditions are determined by the method of selection of ratios and comparison with quantitative experimental data of previously established dependencies. A common approach to the formulation of criteria for imparting new properties to materials by high-energy impacting on them is possible. There is formulated a hypothesis for determining similar change dependences of the physical and operational properties of d-elements on their location in the periodic Table and the statistical weight of atomic stable configuration for various methods of local high-energy impact.