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Project titleThe elaboration of research and technical bases for additive formation of nonuniform structures made of metal, metal-ceramic and high-energy materials by the thermoplastic multiphase compositions extrusion

Research area 09 - ENGINEERING SCIENCES, 09-205 - Development of new structural materials and coatings

Keywordsadditive technologies, nanoparticles, microparticles, nonuniform structures, extrusion, thermoplastic compositions, microencapsulation, pseudoalloys, high-energy materials

Annotation
Additive production almost does not use such multiphase functional materials as pseudoalloys, cermets, intermetallic compounds and high-energy materials. The formation of complex parts by the existing additive technologies using the powder of multiphase and usually polydisperse materials is very difficult or even impossible. In addition, there is no affordable and rather cheap equipment at the global market that can be used for additive formation of irregularly shaped metal parts. Therefore, the elaboration of research and technical bases for the materials and technologies allowing the additive formation of nonuniform structures made of multiphase and polydisperse powder of metal, metal-ceramic, intermetallic compounds and high-energy materials provided at the affordable for most companies equipment seems to be urgent. The goods made of such materials are useful for many spheres including power and microelectronics, aerotronics, manufacturing, formation of irregularly shaped functional and gradient combustion elements, etc. The combination of high-energy materials and additive technologies holds great potential for producing the devices for energy conversion and accumulation that used to be inaccessible due to the traditional manufacturing methods limits. The universal character of additive formation will provide more flexibility during the elaboration of combustion and pyrotechnical compounds. The research problem the project is supposed to solve by theoretical and experimental methods is the elaboration of research and technical bases for additive formation of nonuniform structures made of multiphase materials including metal, metal-ceramic and high-energy ones by the thermoplastic multiphase compositions extrusion. It is necessary to elaborate the thermoplastic compositions based on polymers and homogenous mixtures of nanoparticles and microcomponents of the set phase and powder compounds for the extrusive 3D-printing. The rheological characteristics of the compositions will allow for the formation of nonuniform structures by relatively cheap equipment, namely 3D-printers that are used for polymer details additive formation. Nonuniform structures made of high-energy materials may be used just after being formed. To create metal or metal-ceramic items the polymer should be removed by using PIM-technologies standard methods of material chemicothermal processing and sintering in a high-temperature oven. As a result, a metal or metal-ceramic solid item of the necessary composition and necessary physical and chemical characteristics is created. The thermoplastic compositions based on polymers and powders of model functional materials (metal-ceramis WC-Co, intermetal Ni-Al and pseudoalloy W-Cu) as well as high-energy materials based on aluminium (Al-CuO, Al-Fe2O3 и Al-MoO3) will be formed during the research. The conditions for additive formation of nonuniform structures by the thermoplastic compositions extrusion will be detected. The data on the characteristics of thermoplastic compositions including the powders of model functional and high-energy materials and solid nonuniform structures created by the extrusion of these materials will be gathered. The parameters for materials chemicothermal processing and sintering for manufacturing solid metal and metal-ceramic details will be revealed. The links between the characteristics of details, compositions and their sintering parameters will be determined. Modern experimental research methods and equipment will be used for comprehensive research into the new materials features. The mechanisms of deformation and destruction of the materials provided by the research will be reviewed. The detailed interpretation of the microstructure features will be provided taking into account the anisotropy opportunities. Both physical and mathematical models of the new materials will be provided. The knowledge received under the research will be generalized and the research and technical bases for additive formation of nonuniform structures by the extrusion of thermoplastic multiphase compositions based on polymers and functional/ high-energy materials powders will be elaborated. The solution of the research aims in the evolution of the stress-strained state and fracture in materials obtained by using additive technologies will be important for many related areas of mechanics. The project research novelty lies in the fact that polymer compositions filled with nano- and microparticles of various materials (metals, alloys and ceramics) allow, along with topological design optimization, to develop materials meeting the designed items requirements. Therefore, it will be possible to design the materials provided with the necessary mechanical, magnetic, electrical, energetic, and other features that are difficult or impossible to achieve with single-phase metals or ceramics. Various combinations of initial nano- and micro-sized components make it possible to vary the features of the compositions to create new structural and functional materials and details made of them. For the additive formation of nonuniform structures by extrusion it is necessary to provide sufficient fluidity at the polymer melting point. To obtain the required features of the final item, the filling of the polymer with dispersed components should be heated up to 40 to 60 vol. %. However, at the specified concentration of the dispersed phase in the polymer, the fluidity of the material is sharply reduced, which creates significant difficulties for extrusion molding. The increase in the fluidity due to the increase in material temperature has significant limitations. For instance, heating the high-energy material can lead to the reaction between the components and an uncontrolled release of energy. Nowadays there is no unequivocal scientific and technical solution to this problem. The project is based on the electroexplosive technology developed by the research team for obtaining homogeneous mixtures of nano- and microparticles of various materials. In the preliminary research it was revealed that the use of homogeneous mixtures of various materials from nano- and microparticles in the ratio (25 ... 30) :( 75 ... 70) vol. % provides indicators of fluidity of the composition with the content of dispersed components of more than 60 vol. % at the level of polymeric materials (not less than 12 g / 10 min) and the density of sintered parts is not less than 90%. With the help of such compositions the extrusion method was used to obtain nonuniform parts from microencapsulated nano- and microparticles of heat-resistant and corrosion-resistant alloys KhN70Yu, KhN60VT, 316L. Compositions of nano- and microparticles can also provide a lower sintering temperature of refractory components with low-melting point, high density and low roughness of the final metal and metal-ceramic parts.

Expected results
During the project implementation homogeneous mixtures of nano- and microparticles of functional materials (W-Cu, WC-Co, Ti-Al) with a given disperse and fractional composition will be obtained. Their physical and chemical characteristics will be established. A method for microencapsulation of Aluminium nano- and microparticles with organic layers will be developed. The physical and chemical characteristics of microencapsulated particles will be determined including the temperature of the oxidation reaction beginning and the rate of energy release. The method of obtaining homogeneous mixtures from nano- and microparticles of Al-CuO, Al-Fe2O3, Al-MoO3 with a given disperse and fractional composition will be revealed. Compositions of polymer binders for obtaining thermoplastic compositions will be developed, thermoplastic compositions will be obtained from polymers and mixtures of nano- and microparticles of functional and high-energy materials. The physicochemical characteristics and optimal compositions of thermoplastic compositions for the additive formation of nonuniform structures by extrusion will be highlighted. The analysis of the results obtained will be carried out, the compositions for further research will be selected. The data on the modes of additive formation of nonuniform structures (parts) "green" samples by extrusion of thermoplastic compositions of polymers and functional powders (W-Cu, WC-Co and Ti-Al) and high-energy (Al-CuO, Al-Fe2O3, Al-MoO3) materials will be obtained. The procedures and the parameters for debinding and sintering of complex-profile "green" parts will be developed. Data on the physical and mechanical properties of sintered complex-profile structures depending on the conditions of extrusion molding, debinding and sintering will be obtained. Data on the physical and mechanical features of complex-profile structures based on polymers and high-energy materials powders, depending on the conditions of extrusion formation will be gathered. Research of structural and phase parameters will be carried out at the modern equipment of the Tomsk Materials Science Center for Collective Use. Methods of scanning electron microscopy, X-ray phase analysis will be applied. An important and difficult stage of the work will be the study of the fine crystal structure using atomic force and transmission microscopy. This task is not usual and will require the preparation of model samples for studies by atomic-force microscopy and raster electron microscopy methods. The process of formation of fracture foci of different scales in materials will be described from the standpoint of a new scientific paradigm of inelastic deformation and fracture of solids, combining the methods of deformable solid mechanics (DSM) as well as the ideas and approaches of the theory of nonlinear dynamic systems. Loaded rigid bodies will be considered as typical multiscale nonlinear dynamic systems. This approach makes it possible to study the evolution of the stress-strain state (SSS) in loaded solids, the peculiarities of the formation of fracture centers, including the critical stages of fracture, which develop in modes with aggravation as catastrophes. The results obtained from this viewpoint will be of great importance for the development of modern DSM methods. During the project structural models of materials obtained using additive technologies will be built, and physical models will be developed that describe the features of these composites structural elements mechanical behavior. Test calculations of the evolution of SSS and macroscale destruction will be performed. The evolution of the stress-strain state, the features of damage accumulation and the development of cracks of different scales, including at interfaces, as well as the features of macroscopic fracture of materials of different composition and different structural organization will be numerically evaluated. The obtained experimental data will form the basis for the complex mathematical models describing the fracture mechanics of materials obtained using additive technologies for subsequent prediction of the materials behavior under difficult operating conditions. Based on the research results, scientific and technical foundations for the additive formation of nonuniform structures from compositions based on W-Cu, WC-Co, Ti-Al powders and Al-CuO, Al-Fe2O3, Al-MoO3 powders by extrusion of materials will be developed. The tasks solved in the project seem to be of high world novelty and practical importance. The research is aimed at overcoming some technical shortcomings of modern additive technologies, such as a limited list of raw materials used in 3D printing, high cost of equipment and low level of development of technology for additive formation of items made of high-energy materials. The social significance of the tasks being solved is determined by the numerous areas of potential applications of the items being developed. Thermoplastic compositions can be used both as the material for the additive manufacturing of small-scale batches of customized nonuniform items, as well as for the manufacture of large batches of similar parts using PIM technologies. The approach used in the project allows to increase the range of materials for additive manufacturing. There will be a possibility of extrusion formation of onuniform parts made of functional materials such as W-Cu, WC-Co, Ti-Al, and high-energy materials such as Al-CuO, Al-Fe2O3, Al-MoO3. As a result of the project, the new technology for the production of high-flow feed stocks based on combinations of nano- and microparticles will be created, which will make it possible to mold nonuniform parts from various multiphase materials that are inaccessible to modern additive methods. Feedstocks will be a versatile raw material for both PIM technologies and 3D printing using material extrusion. It will become possible to manufacture nonuniform structures from functional and high-energy materials with new characteristics. The economic significance of the project results is based on the expansion of the range of materials for new production technologies (additive technologies), in which the enterprises of Rosatom, United Engine Corporation ROSTEKH and, in particular, "Aviadvigatel" Corporaton, Scientific and Manufacturing center Polus, "ODK-Klimov" Corporation, State Research Center Federal State Unitary Entreprise "CIAM", etc. will be interested. The introduction of materials with a new level of properties into production processes will allow engineers and designers to create new technical solutions. The implementation of this project in the presented concept corresponds to the global changes in the organization of scientific, technical and innovation activities associated with the compression of the innovation cycle (reduction of the time between the acquisition of new knowledge and the creation and implementation of new technologies). The social significance of the project results lies in the consolidation of the priority for Russian science in creating a full cycle of additive production of new types of metal-matrix composite materials. This task is new for the world level of research in general, and its complete solution does not exist today. During the project implementation, at least 40 publications will be published in peer-reviewed Russian and foreign scientific journals, containing the research results of the project in the journals indexed in the Web of Science Core Collection or Scopus databases. The obtained fundamental results will be presented at International and all-Russian conferences (at least 4 events). 5 bachelor's, 5 master's, 3 master's and 3 doctoral dissertations have been defended by students and postgraduates, employees of Tomsk State University. On the subject of the project, a school of young scientists will be held annually on the territory of the Russian Federation, with the participation of at least ten leading scientists as lecturers in each, as well as at least twenty young scientists under the age of 35 as listeners. During the first 12 months of the project implementation, on the basis of an open competition, at least three young scientists (postdocs) with a scientific degree (postdocs) under the age of 35 from other organizations will be involved in the laboratory to carry out work on the project.

Annotation of the results obtained in 2021
The present project is devoted to the synthesis of homogeneous powder mixtures of nano- and microparticles of W-Cu pseudo-alloy, WC-Co hard metal, Ti-Al intermetallide and the development of the powder additivated thermoplastic composites (feedstocks). The developed composites are designed for layer-by-layer additive molding (AM) of metal and metal-ceramic complex shaped parts by the EAM (Material Extrusion based Additive Manufacturing) method. EAM is a highly promising method for additive molding of complex shaped parts using feedstocks consisting of metal or ceramic powders (up to 60 vol. %) and polymers. Compared to other AM methods of metal and ceramic parts, EAM is easy to use and low in cost. The use of homogeneous powder mixtures of nano- and microparticles will make it possible to obtain feedstocks with better rheological properties compared to the common feedstocks and expand the nomenclature of materials used in additive technologies. A simultaneous electrical explosion (EEW) of tungsten/copper and titanium/aluminum wire pairs, respectively, was used to produce powder mixtures of W-Cu and Ti-Al nano- and microparticles. The optimal modes to obtain powder mixtures of Ti-Al nano- and microparticles has been found to be realized at energy range 0.92<E/Ec<1.2, where E is the total energy input into the titanium and aluminum wires during the high power current pulse, Ec is the sum of sublimation enthalpies of Ti and Al wires. The obtained powders are homogeneous mixtures of spherically shaped nano- and microparticles. The average size of nanoparticles obtained in the above energy range is 93-98 nm, with the average size of microparticles is 1.57-3.65 μm. The phase composition of the powders is represented by alfa-Ti and intermetallides AlTi3 and AlTi. The optimum regime of obtaining a mixture of the W-Cu nano- and microparticles is observed at the energy level Е/Ес ≈ 1.0. In the above EEW regime, powder mixture consisting mainly of spherically shaped W microparticles (average size 1.32 μm) and Cu nanoparticles (average size 54 nm) is formed. The W-Cu powders contain only tungsten and Cu phases due to the absence of mutual solubility of metals both in liquid and solid states. To obtain WC-Co powder mixtures by EEW, tungsten particles at the energy level Е/Ес ≈0.70 (E is the energy introduced into tungsten wires, Ес is the sublimation energy of tungsten) and Co powder mixtures of nano- and microparticles at Е/Ес ≈1.7 (E is the energy introduced into cobalt wires, Ес is the sublimation energy of cobalt) were synthesized. Spherically shaped tungsten microparticles (average size 4.2 µm) and nanoparticles (average size 40 nm) and cobalt (average size 2.1 µm microparticles, 57 nm nanoparticles) are formed at the above energy levels. Tungsten carbide WC particles were obtained by direct carburization of tungsten powders when W is mixed with carbon C. Optimal carburization occurs at 1200 °C for 8 h for the mixture with a C/W ratio being1.4. The WC particles retain the shape and size of the initial tungsten powder. The quantification of the elemental composition shows a carbon content of 50.66 at.% and tungsten content of 49.34 at.%, which is close to the theoretical values for tungsten carbide. WC and Co powders were mixed in the WC:Co ratio 9:1 (wt. %) in a solvent medium under ultrasonic agitation. The study of WC-Co powder showed a homogeneous elemental distribution of C, W and Co, as well as nano- and microparticles in the sample. In addition to the objectives of the project nano/microparticles Ti-Al doped with Mo, W and Cu have been obtained. Doping of Ti-Al alloys with W and Mo improves their heat resistance and high-temperature strength, doping with Cu increases the ductility of the alloys. For the doping the Ti-Al alloys, the EEW of Ti, Al, W (E/Es=0.57); Ti, Al, Mo (E/Es =0.66) and Ti, Al, Cu (E/Es =0.77) wires in argon at a pressure of 0.3 MPa was used. The powders obtained are homogeneous mixtures of nano- and microparticles. The particle size of Ti-Al-W, Ti-Al-Mo, and Ti-Al-Cu is in the range of 20 nm to 7 μm. The bulk materials obtained by sintering Ti-Al-W, Ti-Al-Mo, Ti-Al-Cu powders at 1000 ºC contain AlTi3, AlTi, AlTi2 and W phases, Ti2AlMo phase and Al0.67Cu0.08Ti0.25 phase, respectively. Thus, the possibility of the doping of Ti-Al alloy with metals improving its physical characteristics and mechanical properties has been established. The project has been developed 5 formulations of polymer binders for thermoplastic compositions comprising W-Cu, WC-Co and Ti-Al powders, including 3 two-component and 2 three-component compositions. The components were chosen considering the requirements of low viscosity, high adhesion to powder particles, easy meltability, high mutual solubility and compatibility. Two-component polymer binders contain a scaffold polymer (25 wt.%) and a flowable component (75 wt.%). In addition, the suitability of commercial polyamide designed for the injection molding feedstocksfor the polymeric binder formulations has been established. 18 thermoplastic formulations comprising the polymeric binders and the W-Cu, WC-Co and Ti-Al powders consisting of nano- and microparticles have been obtained. In order to obtain the formulations with reactive W-Cu and Ti-Al powders, a solution mixing technique, preventing oxidation of copper and aluminum particles has been developed. For this, reactive powder suspensions were mixed with the polymer binder solution, then the solvent was removed by heating when stirring. The air-stable WC-Co powder was added to the polymer binder solution in a dry state. After cooling to room temperature and grinding, the powder-binder mixture was extruded three times and pelletized. The following physical and chemical characteristics of the obtained thermoplastic formulations (feedstocks) were determined: density, processing temperature, extrusion rate, uniformity of distribution of micro- and nanoparticles in the polymer binder matrix, chemical interaction of the binder with the powder and preliminary conditions of polymer removal (debinding?). The density of thermoplastic formulation is determined by the density of powders and amounts to 2.5 g/cm3 for Ti-Al; 9.4 g/cm3 for WC-Co; 8.9 g/cm3 W-Cu feedstocks. The processing temperature at which feedstocks can be extruded depends on the composition of the polymer binder and varies from 110-180 °C to 140-180 °C. The extrusion rate is determined more by the properties of the powder contained than by the polymeric binder composition. For Ti-Al feedstocks, the extrusion rate is almost 2.0-2.7 times higher than that for W-Cu feedstocks, and 1.3-2.4 times higher than for WC-Co feedstocks. The difference in extrusion rate of feedstocks with different polymer binders does not exceed 7 % for W-Cu, 18 % for Ti-Al and 33 % for WC-Co feedstocks. The microscopic study of cross-sectional fractures of filaments obtained from the above feedstocks showed the micro- and nanoparticles evenly distributed in the extruded material. At the same time, the computer tomography study showed tungsten large particles to be displaced to the filament outer surface in W-Cu feedstock. IR spectroscopic study has established that the components of the polymer binder do not form chemical bonds with the powders, but protect the powders from oxidation. As part of the project, the optimal compositions of the thermoplastic material for the additive molding of complex-profile parts have been established, with the complex-shaped green parts were made using a 3D printer. Based on the results of the research performed in 2021, 5 papers have been published in the journals cited by Scopus and Web of Science databases (quartile Q1): two of them in the journal "Materials" (Q1 Web of Science), two papers in the journal "International Journal of Refractory Metals and Hard Materials" (Q1 Scopus), one paper in the journal "Metals" (Q1 Scopus). The scientific results of the research have been presented at four conferences of various levels: International Research-to-Practice Conference of Students and Young Scientists "Chemistry and Chemical Technology in the XXI Century", Moscow, Russia, 17-2020, Moscow, Russia. XXT-2021, May 17-20, 2021, Tomsk; International scientific conference "Modern materials and advanced production technologies (SMPPT-2021)", September 21-23, 2021, St. Petersburg; XVIII Russian annual conference of young researchers and postgraduates "Physical chemistry and technology of inorganic materials" (with international participation), November 30- December 3, 2021, Moscow; XI Russian Scientific Conference with international participation "Actual problems of modern continuum mechanics and celestial mechanics - 2021, November 17-19 2021, Tomsk. The School of young scientists "Advanced materials and innovative production technologies" was held within the XI Russian Scientific Conference with international participation "Actual problems of modern continuum mechanics and celestial mechanics", December 1-3, 2021. Link to information resource: Special report. Tomsk Feedstock https://www.youtube.com/watch?v=enasML0tnjY

Publications

1. A. Pervikov, A. Filippov, Y. Mironov, M. Kalashnikov, M. Krinitcyn, D. Eskin, M. Lerner, S. Tarasov Microstructure and properties of a nanostructured W-31 wt% Cu composite produced by magnetic pulse compaction of bimetallic nanoparticles International Journal of Refractory Metals and Hard Materials, Vol. 103, Art. Number 105735 (year - 2022) https://doi.org/10.1016/j.ijrmhm.2021.105735

2. A. Pervikov, M. Krinitcyn, E. Glazkova, N. Rodkevich, M. Lerner Synthesis of tungsten carbide from bimodal tungsten powder produced by electrical explosion of wire International Journal of Refractory Metals and Hard Materials, Vol. 103, 105733 (year - 2022) https://doi.org/10.1016/j.ijrmhm.2021.105733

3. A. Pervikov, N. Toropkov, S. Kazantsev, O.V. Bakina, E. Glazkova, M. Lerner Preparation of Nano/Micro Bimodal Aluminum Powder by Electrical Explosion of Wires Materials, Vol. 14, Is. 21, Art. number 6602 (year - 2021) https://doi.org/10.3390/ma14216602

4. M. Lerner, A. Pervikov, E. Glazkova, N. Rodkevich, N. Toropkov Electrical Explosion Synthesis, Oxidation and Sintering Behavior of Ti-Al Intermetallide Powders Metals, Vol. 11, Is. 5, Art. Number 760, P.1-14 (year - 2021) https://doi.org/10.3390/met11050760

5. O. Kudryashova, M. Lerner, A. Vorozhtsov, S. Sokolov, V. Promakhov Review of the Problems of Additive Manufacturing of Nanostructured High-Energy Materials Materials, Vol.14, Is. 23, Art. Number 7394 (year - 2021) https://doi.org/10.3390/ma14237394

6. - Специальный репортаж. "Томский фидсток" ГТРК «Томск», Специальный репортаж. "Томский фидсток" (year - )

Annotation of the results obtained in 2022
Material extrusion-based additive manufacturing of metal-polymer thermoplastic composites to prepare geometrically complex parts requires creation of model parts and research of their properties at each stage of the manufacturing. At this stage of the project the following was investigated: 1) properties of model parts depending on their processing conditions with subsequent adjustment of thermoplastic composition formulations; 2) conditions of obtaining homogeneous mixtures of nano- and microparticles of high energy materials. Model samples of "green" parts were prepared from thermoplastic composites based on powders of titanium alloy Ti-6Al-4V; bicomponent alloys Ti-29 % wt. Al; W-30 % wt. Cu; WC-10 % wt. Co and 2 types of binders - Lucene polyethylene and Viscowax wax (Luc.+Visc.) and ethylene vinyl acetate, rosin and additives (EVA+ros.). The composites consisting of the first listed binder with all the investigated powders had a higher flowability than those with the second listed binder. Composites including titanium-based powders (Ti-Al and Ti-6Al-4V) showed higher flowability than those with tungsten-based powders (W-Cu and WC-Co). The maximum powder loading for Ti-Al and BT6 containing composites reached 70 vol.% and for W-Cu and WC-Co 60% vol. The polymer binder composition has been found to influence the deformation behavior of the "green" parts - brittle fracture was typical for the parts with (Luc.+Visc.), while for the parts with (EVA+ros.) the plastic deformation stage was typical. The apparent density of the "green" parts printed in the range of 150-190 °C was 65-75% of the calculated density. Acetone has showed the highest efficiency in solvent debinding for 24 h. The debinding efficiency is independent of the powder loading in the composite and of the solvent temperature. Other conditions being equal, the smallest mass of polymer is extracted from the partcontaining WC-Co alloy. It has been found that the residual polymer content after debinding is inversely proportional to the part thickness in the range of 0.8-4.0 mm. A thermal debinding procedure has been developed to remove the residual EVA+ros binder. Between 315 and 415 °C, about 19 % wt. EVA is removed, 80% wt. between 415 and 490 °C. 96 wt% of rosin is removed when heated to 360 °C. The main mass loss of the binder Luc.+Visc. is observed in the interval 320-500 °C, with the removal of Viscowax occurs in the temperature range 270-480 °C, removal of Lucene occurs in the interval 440-490 °C. Both components are almost completely removed. The optimum sintering temperature for W-Cu debinded parts is 1050 °C. The higher the powder content in the composite, the higher the density of the sintered part. After sintering, the average pore size in the copper matrix is 1.0±0.5 µm. The microhardness is in the range of 50-70 HV and is determined by the properties of the copper matrix. The WC-Co parts were produced from a composite based on a mixture of W+7.55 vol. C+9.79 % vol. Co powders, after debinding the parts were sintered at 1300 °С. In the sintered samples, pores of 12±3 μm in size and micron-sized discontinuities between WC particles were observed. Sintered samples with 60 % vol. powder filling had density 11.3±0.5 g/cm3, with 70 % vol. - 12.8±0.6 g/cm3. The lattice parameter of the synthesized tungsten carbide corresponded to stoichiometric WC. The average size of WC particles in the studied materials was 4.1±0.8 μm. Samples of Ti-6Al-4V alloy sintered at 1200 °C showed a globular structure of α-grains surrounded by veins of β-phase. The average size of α-grains was 12.5±0.5 µm. Elemental energy dispersion analysis of the surface thin sections showed the content of elements typical for the alloy Ti-6Al-4V with the average content of elements - Al=5.7±0.5 %, V=4.2±0.5 %. Vickers hardness for the obtained samples was 806±23 HV, which is higher than that for the pure alloy and corresponds to the dispersion strengthened alloy Ti-6Al-4V. Due to the fact that dispersion strengthened TiAl intermetallides are of considerable interest for practical applications, a metal-polymer composite containing 48Ti-48Al-4W (vol. %) was produced from the powder obtained by the wire electric explosion. After debinding, bulk samples were sintered in a vacuum furnace at 1000 °C. According to XRD data, the TiAl and Ti2AlC phases were formed. The microhardness of the sintered samples decreased from 700 - 760 HV to 600 - 650 HV with decreasing particle size. Homogeneous mixtures of nano- and microparticles of high energy materials have been developed using aluminum powders and metal oxides. Al powders were obtained by the wire electrical explosion in an argon atmosphere, with energies input to the wire E/Ec being 0.3, 1.0, 2.0 (Ec - metal sublimation energy). Increasing the input energy leads to a decrease in the average particle size of the micron and nanoscale fractions from 6 to 1.5 µm and from 120 to 92 nm, respectively, as well as a decrease in the active aluminum content from 91 to 86 % wt. The particle size distribution obtained at E/Ec ≈ 0.3 and 1.0 is bimodal, while at E/Ec ≈ 2.0 aluminum is represented by the nanosize fraction. Synthesis of metal oxide powders (MoO3, Fe2O3, CuO) was carried out in an atmosphere of a gas mixture Ar+20% vol. O2 at E > Ec. It has been found that increasing the gas mixture pressure from 0.1 to 0.4 MPa makes it possible to obtain powders with molybdenum oxide content of 95-99 % wt. (MoO3, MoO2 phases), iron oxide - 100 % wt. (Fe3O4, α-Fe2O3 and γ-Fe2O3 phases, no iron in the samples), copper oxide - 94-98 wt. (Cu2O and CuO phases). With increasing gas pressure the average size of Mo oxide particles increased from 51 to 77 nm; Fe oxide particles increased from 39 to 57 nm; Cu oxide particles increased from 46 to 68 nm. To deagglomerate and protect Al particles from the oxidation, a microencapsulation procedure has been developed, which consists in the application of protective layers on the particle surface. Fluoroelastomer LFC-1, acetylacetone (AA), catechol (CT), and triethanolamine-salicylate (TS) and three samples of Al powder were chosen as encapsulating reagents: 1) bimodal powder with maxima of about 0.18 μm and 2.4 μm, 2) bimodal powder with maxima of about 0.33 μm and 1.3 μm, and 3) monomodal powder with maxima of particle size distribution of about 0.3 μm. Al particles were treated by ultrasound (US) in a hexane solution with a microencapsulating reagent followed by removal of the solvent. The optimal treatment mode was 100 W ultrasonic power, treatment time 30 min. The content of active aluminum for the powder microencapsulated with LFC-1 was 87.8%, PC - 86.7%, AA - 86.9%, TC - 85.1%. It was found that the content of active aluminum in the powders was preserved for at least 180 days when the samples were kept at 90% relative humidity. Heating microencapsulated Al powders in the air increases the rate and completeness of the the nanoscale fraction oxidation. To obtain homogeneous mixtures of aluminum and metal oxide particles, US treatment of powder suspensions in hexane was used, since hexane does not affect the structure of the protective layer used. The ratio of components was calculated based on the stoichiometry of chemical reactions. For Al-CuO mixtures, a mass ratio of 1:1.36 was used; for Al-Fe2O3 mixtures, a ratio of 1:2.72; for Al-MoO3 mixtures, a ratio of 1:2.45. It has been found that an uniform distribution of Al nano- and microparticles and CuO, Fe2O3 and MoO3 particles in the mixtures is achieved at an ultrasonic power of 100 W for 20 min. The microencapsulation thus improves the homogeneity of mixtures of nano- and microparticles Al and metal oxides, which is due to the disagglomeration effect of microencapsulating reagents when mixed in a liquid medium. The developed method of obtaining mixtures of nano- and microparticles Al-CuO, Al-Fe2O3, Al-MoO3 provides a high homogeneity of component distribution in the mixture bulk. However, the obtained mixtures are characterized by a tendency to auto ignition, which requires compliance with increased safety measures when handling them. Public information about the project can be found at https://rscf.ru/news/interview/, https://www.youtube.com/watch?v=fJZIuRNzcEg&t=444s, https://vk.com/wall-214520833_1162, https://news.tsu.ru/news/sozdannye-v-tgu-fidstoki-zamenyat-importnye-analogi/, https://news.tsu.ru/news/sozdannye-v-tgu-materialy-dlya-3d-pechati-vykhodyat-na-rynok/.

Publications

1. Krinitcyn M.G., Pervikov A.V., Kochuev D.A., Lerner M.I. Powder Injection Molding of Ti-Al-W Nano/Micro Bimodal Powders: Structure, Phase Composition and Oxidation Kinetics Metals, Том 12, Выпуск 8, Номер статьи 1357 (year - 2022) https://doi.org/10.3390/met12081357

2. Krinitcyn M.G., Svarovskaya N.V., Lerner M.I. The effect of low-temperature auto-ignition of W–Cu2O nanopowders with core-shell structure Vacuum, Том 195, Номер статьи 110837 (year - 2022) https://doi.org/10.1016/j.vacuum.2021.110837

3. Kudryashova O.B., Toropkov N.E., Lerner M.I., Promakhov V.V., Vorozhtsov A.B., Mirovoy E. Mathematical modeling of high-energy materials rheological behavior in 3D printing technology Heliyon, Article number e12026 (year - 2022) https://doi.org/10.1016/j.heliyon.2022.e12026

4. Lerner M.I., Pervikov A.V., Glazkova E.A., Rodkevich N.G., Suliz K.V., Kazantsev S.O., Toropkov N.E., Bakina O.V. Synthesis of Ti-Al Bimodal Powder for High Flowability Feedstock by Electrical Explosion of Wires Metals, Том 12, Выпуск 3, Номер статьи 478 (year - 2022) https://doi.org/10.3390/met12030478

5. Lozhkomoev A.S., Kazantsev S.O., Bakina O.V., Pervikov A.V., Chzhou V.R., Rodkevich N.G., Lerner M.I. Investigation of the Peculiarities of Oxidation of Ti/Al Nanoparticles on Heating to Obtain TiO2/ Al2O3 Composite Nanoparticles Journal of Cluster Science, 2022 (year - 2022) https://doi.org/10.1007/s10876-022-02382-8

6. Lozkomoev A.S., Pervikov A.V., Kazantsev S.O., Suliz K.V., Veselovskii R.V., Miller A.A., Lerner M.I. Controlled Oxidation of Cobalt Nanoparticles to Obtain Co/CoO/Co3O4 Composites with Different Co Content Nanomaterials, Том 12, Выпуск 15, Номер статьи 2523 (year - 2022) https://doi.org/10.3390/nano12152523

7. Pervikov A.V., Suliz K.E., Kazantsev S.O., Rodkevich N.G., Tarasov S.Yu., Lerner M.I. Preparation of nano/micro-bimodal Ti/Al/(Mo, W, Cu) powders by simultaneous electrical explosion of dissimilar metal wires Powder Technology, Том 397, Номер статьи 117093 (year - 2022) https://doi.org/10.1016/j.powtec.2021.117093

8. Promakhov V.V., Matveev A.E., Babaev A.S., Shulz N.A., Toropkov N.S., Vorozhtsov A.B., Lerner M.I. 3D Printing Using Ti-Al Nanopowders: Mechanisms of Structure Formation Metals, Том 12, Выпуск 10, Номер статьи 1737 (year - 2022)

9. Krinitcyn M.G., Lerner M.I. Использование нанопорошковых материалов в аддитивной технологии экструзии термопластичных многофазных композиций IX Международная конференция с элементами научной школы для молодежи «ФУНКЦИОНАЛЬНЫЕ НАНОМАТЕРИАЛЫ И ВЫСОКОЧИСТЫЕ ВЕЩЕСТВА». Суздаль. 3 - 7 октября 2022 г./ Сборник материалов. – М: ООО «Буки Веди», 2022, 249 с., стр. 69 (year - 2022)

10. Kudryashova O.B., Toropkov N.E., Vorozhtsov A.B., Lerner M.I. Mathematical model of extrusion in FDM 3D printing technology Book of Abstracts of L International Conference “Advanced problems in mechanics”, стр. 44 (year - 2022)

11. - РНФ делает благое дело.... Дайжест новостей Российского научного фонда, №1, 2022, 27.04.2022 (year - )

12. - Приоритет 2030: Созданные в ТГУ материалы для 3D-печати выходят на рынок Сайт ТГУ, - (year - )

13. - Новые материалы для 3D-принтинга В контакте, - (year - )

Annotation of the results obtained in 2023
Project under the RSF agreement № 21-79-30006 "Development of Scientific and technical bases of additive molding of complex profile structures made of metal, metal-ceramic and high-energy materials by extrusion of thermoplastic multiphase compositions" is devoted to the development of advanced technology of the part additive molding as an alternative to existing technologies. For this purpose, an additive technology based on the production of complex shape parts from composites containing a metal powder and a polymer binder (green part). Further, the polymer binder is removed with using a solvent, and the part (brown part) is sintered in a high temperature vacuum furnace. Varying the composition of the nano- and micro-sized particles used in the formulations allows to obtain parts with specified mechanical, magnetic, electrical and electrical properties. mechanical, magnetic, electrical, etc. properties, which are difficult or impossible to achieve using common methods. In the third year of the project implementation the work on finalization of metal-polymer compositions (feedstocks) based on WC-Co, W-Cu to improve the properties of finished parts was continued. WC-containing compositions with minimum residual carbon content and additives suppressing WC grain growth have been developed and optimal parameters of the part additive molding process have been determined. Also, WC-29NK compositions have been developed, in which cobalt metal powder was replaced by cheaper cobalt-containing 29NK alloy, and green parts were prepared from the WC-29NK compositions by additive molding. The sintered parts showed a bending strength of 113 MPa, Young's modulus of 198 GPa, and Vickers microhardness of 1120 HV 0.5/10. The fabrication of green parts by the additive molding consists of successive depositing of thin layers of metal-polymer composite. Accordingly, the properties of the sintered part may depend on the orientation of the layers formed when printing the sample. The physical and mechanical properties of W-Cu pseudo-alloy and WC-Co samples have been found to depend on the layer orientation. It is noteworthy that the hardness of the W-Cu pseudo-alloy is 17 % higher than it follows from theoretical estimates. The reason for this phenomenon remains to be established. The flexural strength of the samples depends on the direction of loading. Under normal loading relative to the layers, the strength is higher than that under loading parallel to the superimposed layers. W-Cu pseudo-alloys are widely used in electrical engineering as sliding contacts, so tribological characteristics of the material are an important part of the product properties. When body moving across the layers, the friction coefficient is higher (0.86) than that when moving along the layers (0.79). The obtained data are close to those presented in the literature. When moving along the layers, wear mass loss is practically absent (0.1 %), while when moving across the layers wear mass loss is 2.2 %. Probably, wear occurs due to the detachment of sample microparticles due to interlayer defects. Increase of erosion, wear and radiation resistance of W-Cu-based composites is achieved by alloying the pseudo-alloy with such metals as Ni, Zn and Cr. The conditions for the preparation of W-Cu-Zn and W-Cu-Ni-Cr powders consisting of micro- and nanoparticles have been established. The mentioned powders were used to prepare feedstocks and printed parts, as well as the parameters of polymer binder removal and sintering have been determined. The value of microhardness of the prepared W-Cu-Zn samples is about 317 ± 16 HV, and for W-Cu-Ni-Cr composition - 252 ± 17 HV. These values agree with the data for composites W50Cu50 (at. %) obtained by powder metallurgy methods. Ti-Al based alloys demonstrate high strength and high-temperature plasticity at low specific weight. Additions of W and Mo in Ti-Al alloys provide better corrosion resistance properties of the material. The difficulty of mechanical processing of these alloys can be eliminated by the additive manufacturing methods, including extrusion 3D printing. As a result of this research, the electroexplosive synthesis modes of TiAl, Ti48Al48Mo4, Ti46Al46Mo8, Ti42Al43Mo15 and Ti48Al48W4, Ti46Al46W8, Ti42Al43W15 powders have been established. Feedstocks have been prepared from Ti-Al, Ti-Al-W, Ti-Al-Mo powders with EK2065 and MC2162 binders, from which complex shaped parts have been printed.The addition of Mo and W has been shown to increase the hardness of Ti-Al alloy compared to the base composition Ti50Al50. Young's modulus and microhardness values of Ti-Al-Mo and Ti-Al-W samples agree with literature data for Ti-Al alloys with β stabilizer additives. The parameters of extrusion 3D-printing process have been determined, providing minimal anisotropy of physical and mechanical properties for parts prepared of the materials developed. Al-Cu based parts are of interest for various practical applications, for example, such materials are used as electrical contact materials, including the soldering Al and Cu. Also Al-Cu alloys are used in the construction of aircraft, car wheels, machine tools, etc. Highly filled feedstock with the content of dispersed phase being 89 wt% has been obtained from Al-Cu alloy powder synthesized by electro-explosive method and polymer binder MS2162. The optimal modes of additive printing, solution debinding in acetone and sintering of parts have been established. Physical and mechanical properties of the sintered parts have been studied. As follows from the studies the developed feedstock is suitable for additive molding of parts from Al-Cu alloy by FDM technology providing high mechanical strength and low porosity. The optimum form of feedstocks for additive molding of parts by extrusion of metal-polymer compositions - pellets - has been determined. For additive molding of complex profile structures based on Al-CuO, Al-Fe2O3, and Al-MoO3 nanothermites, the polymer binders - fluorocarbon rubber (LFC-1) and ethyl-vinylacetate copolymer (EVA) have been established. The method of combining dispersed phases and polymers has been established - mechanical homogenization at 500 rpm and time from 1 to 2 min. The highest degree of homogeneity of nanothermite constituent distribution in the polymer binder is observed when triethanolamine salicylate (1% of the composition mass) is used as an encapsulating reagent, and fluorocarbon rubber (10% of the composition mass) is used as a polymer binder. Such characteristics as combustion initiation time, combustion rate, sensitivity to impact and friction, energy at which ignition of nanothermite-based compositions occurs under the influence of electric discharge have been established for the developed compositions. Depending on the application areas, varying the composition of the polymer binder and nanoparticle encapsulation coating has been shown to allow to set the initiation time and burning rate of the nanothermite. For additive molding of complex profile structures, the compositions containing not more than 25 wt. % of the polymer binder LFC-1 (solvents - acetone, butyl acetate, ethyl acetate) and 20 wt. % of EVA (solvent - toluene) have been selected. Public information about the project is available at https://vk.com/video-188687325_456239419; https://www.youtube.com/watch?v=cxNw2AyezYM&t=1s; https://rscf.ru/news/interview/, https://www.youtube.com/watch?v=fJZIuRNzcEg&t=444s, https://vk.com/wall-214520833_1162, https://news.tsu.ru/news/sozdannye-v-tgu-fidstoki-zamenyat-importnye-analogi/, https://news.tsu.ru/news/sozdannye-v-tgu-materialy-dlya-3d-pechati-vykhodyat-na-rynok/; https://www.youtube.com/watch?v=enasML0tnjY.

Publications

1. Bakina O.V., Svarovskaya N.V., Chzhou V.R., Glazkova E.A., Lozhkomoev A.S., Ivanova L.Yu., Spirina L.V., Lerner M.I. Особенности формирования пористых композитов на основе электровзрывного нанопорошка Ti/Al для костных имплантов Физическая мезомеханика (Physical Mesomechanics), - (year - 2024)

2. Krinitcyn M.G.,Pervikov A.V., Svarovskaya N.V., Lozhkomoev A.S., Lerner M.I. Extrusion-Based Additive Manufacturing of the Ti6Al4V Alloy Parts Coatings, Vol. 13, Is. 6, Article number 1067 (year - 2023) https://doi.org/10.3390/coatings13061067

3. Lebedev M.S., Promakhov V.V., Shultz N.S., Vorozhtsov A.B., Lerner M.I. Effects of Sintering Temperature on the Microstructure and Properties of a W-Cu Pseudo-Alloy Metals, Vol. 13, № 10. Art. num. 1741 (year - 2023) https://doi.org/10.3390/met13101741

4. Lerner M.I., Suliz K.V., Pervikov A.V., Tarasov S.Yu. Micron- and Nanosized Alloy Particles Made by Electric Explosion of W/Cu-Zn and W/Cu/Ni-Cr IntertwinedWires for 3D Extrusion Feedstock Materials, Vol. 16, Is. 3, art. num. 955 (year - 2023) https://doi.org/10.3390/ma16030955

5. Lozhkomoev A.S., Bakina O.V., Kazantsev S.O., Glazkova E.A., Rodkevich N.G., Lerner M.I. Antibacterial electro-explosive Co/CoO composite nanoparticles: Synthesis, structure, magnetic and antibacterial properties Journal of Magnetism and Magnetic Materials, Vol. 580. Art. num. 170892 (year - 2023) https://doi.org/10.1016/j.jmmm.2023.170892

6. Lozhkomoev A.S., Krinitcyn M.G., Kazantsev S.O., Vornakova E.A., Svarovskaya N.V., Glazkova Е.А. Development of approaches for forming complex profile parts from Al-Cu alloys using the metal fused filament fabrication technology Progress in Additive Manufacturing, - (year - 2023)

7. Toropkov N.E., Sagun A.I., Kudryashova O.B., Lerner M.I. Optimal conditions for ultrasonic treatment of powder suspensions to obtain homogeneous thermite mixtures Russian Physics Journal, - (year - 2023)

8. Chzhou V.R., Bakina O.V., Svarovskaya N.V. Пористые биосовместимые композиты Ti/Al/TiO2: получение и характеризация Тезисы докладов Международной конференции «Физическая мезомеханика. Материалы с многоуровневой иерархически организованной структурой и интеллектуальные производственные технологии», 11-14 сентября 2023 года, Томск, Россия. – 676 с., C. 615-616 (year - 2023)

9. Promaxov V.V., Lerner M.I. Laws of formation of structure of materials based on nanophers of Ti-Al sistema nanopours created with the application of additional technologies Abstracts of the Abstracts of the V International Conference and School "Advanced High Entropy Materials" (Saint Petersburg, Russia, October 9-13,2023) / ed. G.A. Salishchev, M.S. Tikhonova, E.A. Povolyaeva. – Belgorod : LLC "Epicenter", 2023. – 173 p., C.118 (year - 2023)

10. Toropkov N.E. Разработка фидстоков для 3D печати из псевдосплава W-Cu Проблемы механики: теория, эксперимент и новые технологии : Тез. докл. XVII Всерос. конф. молодых ученых 26 февраля — 6 марта 2023 г., Новосибирск — Шерегеш / под ред. Е. И. Крауса; Новосиб. гос. ун-т. — Новосибирск : ИПЦ НГУ, 2023. — 240 с., С. 193-194 (year - 2023)

11. Toropkov N.E., Sagun A.I., Kudryashova O.B., Lerner M.I. Оптимальные режимы ультразвуковой обработки суспензий порошков для получения гомогенных термитных смесей Тезисы докладов Международной конференции «Физическая мезомеханика. Материалы с многоуровневой иерархически организованной структурой и интеллектуальные производственные технологии», 11-14 сентября 2023 года, Томск, Россия. – 676 с., С. 64-65 (year - 2023)

12. - Марат Лернер. "Аддитивные технологии" Час науки. Научно-популярная программа ГТРК "Томск", 2023, 11:20 (year - )