Scientific Journal of KubSAU

This article presents a complex method of formation of the surface-modified layers of materials with shape memory effect, including high-speed flame spraying powders TiNiCo with a cobalt content of 2 and 5%, subsequent thermal and thermomechanical treatment, allowed forming nanostructured surface layers with a high level of functional and operational properties. It is shown that the TiNiCo complex processing layer allowed reducing the porosity of coatings and increasing the strength of adhesion of the coating to the substrate. Surface modification TiNiCo for optimal regimes allowed increasing fatigue life under high cycle loading by 30-40% and wearing 3-3.5 times. Based on comprehensive research metallophysical surface layers obtained new information on the nanoscale composition

The article contains a block diagram of the mechanical activation process of multicomponent shape memory materials, taking into account the variety of influencing factors. We have proposed to evaluate the reactivity of the sprayed material using the energy criterion (energy intensity), determined by the additivity concept as an energy amount of the raw material and energy accumulated during mechanical activation. Power consumption of the raw material depends on the chemical and phase composition and is determined based on the similarity between the melting energy, plastic deformation and fracture on the thermodynamic characteristics and diagrams of the systems. The energy stored in the MA is determined on the basis of X-ray structural analysis. We have demonstrated that with increasing of grinding precision there is growth in the number of active centers, which enables nanostructurization of surface layers in high-velocity oxygen-fuel spraying (HVOF). According to the study, we have developed practical recommendations for effective implementation of mechanical activation of the shape memory material

The article is dedicated to the determination of conditions for solid bodies’ fragmentation, providing minimal size of particles by means of their mechanical dispersion through the example of powders of titanium carbide (TiC), cubic boron nitride – borazon (CBN) and boron carbide (B4C). The theoretical and practical aspects of the process of mechanical fragmentation of particles of solid powder materials in ball mill for their further utilization in furnace charge for high-speed gas-flame sputtering of wear-resistant composite materials are examined in the article. Methods of preliminary calculation of minimum allowable size of solid particles of powder materials during mechanical fragmentation, based upon Griffiths’ mechanical theory of rapture using experimental data for hardness of material and its yield are proposed and theoretically substantiated. There we have the results of experiments on mechanical fragmentation of titanium carbide in attritor, boron carbide and cubic boron nitride in centrifugal planetary mill, confirming correctness of theoretical propositions and calculations are set out. Recommendations on mechanical fragmentation of solid powder materials in ball mills are formulated as well

The combined method of formation of the “Steel - superficial of materials with effect of memory of the form on the basis of TiNiCu” composition, which includes mechanical activation of powder, the high-speed gas-flame dusting, the subsequent thermo-mechanical processing is considered. The operating parameters are defined and the optimum modes of processing providing formation of the layers with nano-sized structure are recommended, chemical and phase composition of which corresponds to the shape memory effect

Based on the analysis of the phase composition, the average grain size measured by high resolution electron microscopy and multifractal parameterization structure shows the relationship of coating properties with their structural-phase state. The regularities of the evolution of the structural parameters and multifractal characteristics of the surface layers of materials with shape memory can predict the properties of the composition of the "steel-coating". On the basis of experimental studies, it has been shown that mechanical activation of powders of materials with shape memory effect based on TiNiTa makes it possible to create an effective technology training sprayed material which will generate nano-structured surface layers by high-speed flame spraying. The influence of the mechanical activation of TiNiTa powder on the quality of surface layers formed by high-speed flame spraying was investigated, and a significant improvement in the structure of the surface layer was found, with reduced porosity, high adhesion, and, consequently, increased functionality and mechanical properties. The evolution of the structure at all stages of surface modification based on the fractal approach multifractal parameterization method, which is based on qualitative analysis and instrumental methods in addition to classic microstructure parameters like grain size and specific area related to the physical and mechanical properties, is quantitative information. It was established experimentally that after high-speed flame spraying, the performance characteristics of mechanically activated shape memory TiNiTa powder improved: cyclic durability under high-cycle fatigue increased by about 35.6%, and the wear resistance increased by 3.6 times

We have performed a mechanical activation of TiNi powder; as a result, PN47T26TS27 powder after mechanical activation is flat discs ranging in size from 10 to 30 microns. We have developed a composition technology "steel - material with shape memory effect" by high-velocity oxygen-fuel spraying of mechanically activated powder based on TiNi. We have determined the optimal processing parameters to ensure a nanostructured surface layer. We have estimated the process parameters of highvelocity oxygen-fuel spraying. The basic parameters are: propane flow rate 60-85 l / min, that of oxygen 120-160 l / min, flow rate of powder and carrier gas (argon), distance and angle of deposition, and movement speed of the torch, the rotation speed of the coated workpieces. We have carried out macroand microanalysis of surface layers of Ti-Ni based alloy, obtained on proven technology. We have studied the effect of TiNi doping with a third component Zr. The simulation allows us to predict the possibility of using surface modification of products with SME material TiNiZr under certain conditions of temperature and to determine the desired composition of the coating, which provides a positive effect. We have made tests on steel 45 with a surface-modified layer TiNiZr under dry friction conditions, during which there is a significant increase in temperature, we have confirmed the effect of improving the wear resistance