THERMODIFFUSION SATURATION OF THE SURFACE LAYERS OF α-TITANIUM BY OXYGEN, NITROGEN, CARBON

Abstract

The purpose of the study is to analytically assess the depth of the gas-saturated zone in the case of a single-component diffusion saturation of alpha-titanium with nitrogen, oxygen and carbon from a rarefied controlled gas environment. Results. Based on the analysis of the literature data, the work schematically shows the interaction of alpha titanium with the elements of implementation and presents the processes with the corresponding parameters that characterize. It is shown that the surface impurity concentration is equal to the equilibrium concentration and is established instantly and does not depend on time. Consequently, with the proposed generalized nonstationary boundary condition in the absence of diffusion of impurities into the volume of the metal, the time dependence of its surface concentration is given, determined by the intensity of surface processes. The dependence of the relative change in the microhardness in the diffusion zone of titanium due to dissolved nitrogen (without taking into account the contribution of nitride inclusions) is presented. Analytically calculated concentration profiles of nitrogen generally correlate well with the distribution of the corresponding relative changes in microhardness in the surface layer. Analytical calculations of the concentration profiles of oxygen, nitrogen and carbon in titanium at a saturation temperature of 700 °C are presented. Practical value. The results obtained will make it possible to preliminarily estimate the size of the fortified near-surface layer depending on the parameters of chemical-thermal treatment and select the optimal parameters of thermal diffusion treatment to ensure the formation of reinforced layers on products made of alpha-titanium based on elements of interstitial in order to increase the functional properties.