Abstract
AbstractThe efficiency and service life of products made from metal-ceramic tool alloys and used as cutting tools and friction units are determined by a combination of physical and strength properties of their surface layers with a thickness of up to 200 μm. Therefore, much attention is paid to their improvement at the present time. An effective way to increase the operational properties of the metal-ceramic alloy products is to modify the structure and the phase composition of the surface layers by forming multi-scale internal structures with a high proportion of low-dimensional (submicro and nano) components. For this purpose, surfaces are treated with concentrated energy fluxes. Pulse electron-beam irradiation (PEBI) in an inert gas plasma is one of the most effective methods. This chapter presents results of theoretical and experimental studies of this process. An example is the nanostructured hardened surface layer on the TiC-(Ni-Cr) metal-ceramic alloy (ratio of components 50:50) formed by PEBI in the plasma of argon, krypton, and xenon. Its multi-level structure, phase composition, as well as tribological and strength properties are shown.
Highlights
Processing materials and products with concentrated energy fluxes to modify the structure, physical and strength characteristics of their surface layers is one of the effective ways to improve operational properties of metals and alloys
The values were maximum at the surfaces of titanium carbide particles (Fig. 13). These results indicated the intensive dissolution of titanium carbide particles in the molten nickel-chrome binder and its excessive saturation with titanium and carbon, as well as proved the inevitability of the formation of the multiphase composition in the surface layer during its high-rate cooling after electron-beam pulses
3.6 The Effect of the Nanostructured Surface Layer on Transverse Bending Strength. It follows from the distribution of the titanium carbide particle sizes, that the top part of the surface layers had the structure included columnar titanium carbide nanoparticles oriented perpendicular to the irradiated surface and the nickel-chrome binder interlayers
Summary
Processing materials and products with concentrated energy fluxes to modify the structure, physical and strength characteristics of their surface layers is one of the effective ways to improve operational properties of metals and alloys. The main patterns of the structural and phase transformations in the surface layer of the TiC-(Ni-Cr) metal-ceramic alloy under PEBI are determined primarily by electron-beam energy density, as well as the number of pulses and pulse duration. An analysis of the temperature profiles and the surface layer depth enables to estimate the ranges of the experimental parameters (electron-beam energy density, the number of pulses and pulse duration) for the surface layer structure modification by PEBI. Taking into account that the temperature profiles in the surface layer are formed precisely during the first pulse and remain almost unchanged an increase in the number of pulses changes only the duration of the interfacial interaction of the components in the TiC-(Ni-Cr) metalceramic alloy under non-equilibrium temperature–time conditions for the specified electron-beam energy density and pulse duration values. An increase in the content of the ceramic component in the TiC-(Ni-Cr) metal-ceramic alloy enhances the maximum heating temperature in the surface layer, as well as the temperature gradient in the surface layer
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