FORMATION BY THE ELECTRON-ION-PLASMA METHOD OF STEEL SURFACE LAYERS CONTAINING SILICIDES OF REFRACTORY METALS

10.25712/ASTU.1811-1416.2023.01.007

Abstract

The result of the modification of the surface of metals and alloys by combined treatment (deposition of thin metal films with subsequent mixing under the action of high-intensity energy flows) is the formation of a gradient structure of the surface layer of the material, characterized by depth-changing concentration of alloying elements, phase composition and the state of the defective substructure, which has a positive effect on mechanical and tribological properties of the material. The aim of this work is the formation of high-strength silicide- and nitride-containing surface layers during combined processing in a single vacuum cycle, including the deposition of coatings of refractory metal and silicon, irradiation with a high-intensity pulsed electron beam, and additional nitriding in a low-pressure gas discharge plasma. Modification combining multi-cycle (up to five cycles of irradiation of the «film/substrate» system) high-speed melting of the «film (Si (0.2 µm)+Nb (0.2 µm))/(40Cr steel) substrate» system with an intense pulsed electron beam was carried out using the COMPLEX installation (Institute of High-Current Electronics SB RAS) in a single vacuum space. Some of the specimens were additionally subjected to nitriding in a low-pressure gas discharge plasma (773-873 K, 1-5 hours). Studies were carried out and a combined modification mode, which made it possible to repeatedly increase the wear resistance (more than 100 times) and microhardness (more than 5 times) of the surface layer of the original steel was identified. Assumptions about the physical nature of the increase in the tribological and strength properties of the material were proposed.