Optimization of the synthesis of mesoporous titanosilicate ETS-10: Problems and unexpected difficulties

    Machines. Technologies. Materials., Vol. 16 (2022), Issue 3, pg(s) 93-95

    We focused on the synthesis and subsequent use of mesoporous titanosilicate ETS-10 for industrial water purification. Numerous attempts have been made to optimize the conditions and reagents used for the synthesis of the ETS-10. The main problem we faced in the synthesis of ETS-10 is the production of “pure” phase and it was related to the type of titanium source. Various sources of titanium were used – titanium tetrachloride, anatase (anatase 92% and rutile 6%), nanosized titanium dioxide (Degussa P25) etc. The use of liquid titanium tetrachloride, due to its high hydrophilicity, leads to difficulties in reproducible control of the quantities of used reagents, which leads to the formation of unwanted crystalline phases, especially if the synthesis is carried out in small volumes. In addition, the optimized by us synthesis attempts included a reduced reaction time – up to 24 hours – and lower temperatures (up to 200 oC). For comparison standard synthesis is carried out for 72 h at 230 oC. As a result of the experiments, ETS-10 with minimal SiO2 residues was obtained in 24 hours at 200 oC using nanosized anatase.


    Caprolactam distillation: implementation engineering solutions for rotary thin film evaporator

    Machines. Technologies. Materials., Vol. 16 (2022), Issue 1, pg(s) 33-37

    The paper proposes a reconstruction of the distillation of caprolactam for more complete removal of water from the finished product, removing the droplet phase during the process in thin-film evaporators, will improve the final product performance by eliminating the inappropriate indicators alkali content and the optical density of the final product and to ensure its stable high quality. The relevance of the work presented directions for improving the process of production of caprolactam – raw ingredient for the preparation of polymeric materials used in various sectors of the economy. Describes the causes affecting the quality characteristics of the finished products produced from caprolactam. the implementation the liquid distributor and the centrifugal separator would reduce 5 – 6 times droplet entrainment to ensure complete removal of moisture from the final product, will reduce the alkali content in the final product, reduce the rate of optical density and thus bring trademark caprolactam by indicators «alkalinity» and «optical density» to the level of the highest quality product.

  • Nanosized ZnO and ZnO@zeolite composite prepared via sonication method

    Materials Science. Non-Equilibrium Phase Transformations., Vol. 7 (2021), Issue 3, pg(s) 89-92

    ZnO nanosized materials are well known for their photocatalytic and antibacterial properties. Their implication in water treatment and environmental protection, especially as a part of composite materials, has been an object of study of a great number of researchers working in the field. Zeolites are excellent candidates for support of composites preparation with semiconductor oxides since they are nonhazardous, non-expensive and naturally abundant materials. In order to synthesize nanosized ZnO with well-developed surface area and uniform size distribution in pristine form and supported on zeolite, we applied the method of precipitation assisted by sonicatio n. As prepared ZnO nanoparticles and the composite ZnO-zeolite were characterized by XRD, SEM and UV-Vis spectroscopy. The ZnO crystalized in wurtzite structure in both materials. The morphology of ZnO nanoparticles was affected by the zeolite framework, as in the composite the ZnO was formed in-situ at the presence of zeolite. The ultrasonic irradiation during the precipitation of Zn(OH)2 and aging of the reaction mixture causes activation of the zeolite surface and prevents the aggregation of ZnO particles. In result evenly distributed ZnO nanoparticles were obtained in the composite.


    The impact of high voltage electric discharge treatment on the properties of Cu – Al powder mixture

    Machines. Technologies. Materials., Vol. 15 (2021), Issue 6, pg(s) 248-251

    Studies of the impact of high voltage electric discharge (HVED) treatment on the dispersion and phase composition of 87,5 % Al + 12,5 % Cu powder system were performed. It was shown that HVED treatment in kerosene with specific treatment energy of 5 MJ/kg leads to the decrease of mean diameter of treated powder from 15 to 13 μm, and the increase of specific treatment energy leads to the decrease of mean diameter of treated powder from 15 to 6 μm. X-ray diffraction analysis shows that CuAl2 and Al4C3 are synthesized in all considered treatment regimes.
    HVED treatment with increased specific treatment energy leads to the increase of quantity of synthesized Al4C3 phase. The use of “three point – plane” electrode system instead of “point – plane” during HVED treatment of 87,5 % Al + 12,5 % Cu powder system leads to the increase of quantity of synthesized Al4C3 and CuAl2 phases, while the efficiency of powders dispersion slightly decreases. Up to 40% of particles in powder mixture, treated by HVED in kerosene with the use of “three point – plane” electrode system, have diameter close to the diameter of the initial powder mixture


    On intensifying the research processes of regular motions transformation

    Machines. Technologies. Materials., Vol. 14 (2020), Issue 1, pg(s) 3-11

    The study is a review of the scientific and applied content of the research carried out over the years on the topic, both worldwide and by the authors. The research is structured in a way that presents the topic in its active development over the years, which substantially proves its permanent relevance. The development of the researches of the spatial transformation of motions, oriented towards the synthesis and analysis of spatial transmissions with innovative characteristics, at this stage and up to the present moment for Bulgaria are realized exclusively at the Institute of Mechanics at Bulgarian Academy of Sciences (BAS). The content of the researches carried out at the Bulgarian Academy of Sciences clearly determines their market orientation and, therefore, their place of development was in the “Centre of competence MIRACle – Mechatronics, Innovation, Robotics, Automation, Clean Technologies” at the Institute of Mechanics. The above said makes it inexplicable the decision of the former management of the institute, in the face of Prof. Vasil Kavardjikov (Director) and Assoc. Detelina Ignatova (Project Manager), to ignore this topic when designing a project for the creation of the Competence Centre.



    Machines. Technologies. Materials., Vol. 13 (2019), Issue 11, pg(s) 515-518

    In this paper, we consider the theoretical foundations of the synthesis of ceramic materials from natural aluminosilicates with the addition of technogenic materials (lead and copper slag) using powder metallurgy methods. The characteristics of the feedstock, properties are presented, the geographical deposits of natural components are shown. The possibility of obtaining pelletized, granular, and block ceramic materials based on natural and technogenic sorbents of Kazakhstan is shown by powder metallurgy methods.

  • The impact of frequency composition of consolidation current on the structure and physical-mechanical properties of Ti-Al-C system metal matrix composites

    Materials Science. Non-Equilibrium Phase Transformations., Vol. 5 (2019), Issue 4, pg(s) 109-111

    The impact of industrial frequency (50 Hz) current with the voltage of U = 10 V while using the Field Activated Pressure Assisted Synthesis (FAPAS) method as well as the impact of superposition of direct and alternating (with 10 kHz frequency) currents with the voltage of U = 2 V while using Spark Plasms Sintering (SPS) method on the phase composition, structure and properties of Ti-Al-C system metal-matrix composites, consolidated from the powder mixtures, prepared by high voltage electric discharge, is experimentally studied. It is shown, that using SPS and FAPAS methods allows synthesis of materials, dispersion-strengthened by phases of TiC and Al4C3 carbides and Ti3AlC2 MAX-phase. It is found out, that using FAPAS method allows obtainment of Ti-Al-C system composites with higher values of density, hardness and wear-resistance, than those of materials obtained by SPS due to more homogeneous structure. Such a differences can be explained by the fact that high frequency (10 kHz) current component promotes movement of disperse phase inside the matrix, which leads to the agglomeration of strengthening particles as well as to increase of obtained composite porosity up to ~ 8 %.


    Effect of Al-Ti-C system master alloy high energy synthesis on efficiency of Ni based superalloy inoculation

    Machines. Technologies. Materials., Vol. 13 (2019), Issue 8, pg(s) 331-334

    The possibility of high energy synthesis of Ti–Al–C system powder grain refiner by using high voltage electric discharges for treatment of powder mixtures of 75 % Ti + 25 % Al and 85 % Ti + 15 % Al composition in kerosene with subsequent briquetting by spark plasma sintering is shown in present work. It is found out that high voltage electric discharge treatment of powders leads to the increase of dispersity as well as to synthesis of new carbon containing phases during chemical interaction between system components and products of working hydrocarbon liquid destruction. The possibility of controlling this process by changing initial composition of powders, specific treatment energy and spatial distribution of plasma formations by changing electrode system type is shown. It is also shown that changing master alloy synthesis parameters allows controlling inoculation efficiency. Thereby it is possible to achieve surface or volumetric inoculation, so selective increasing of plastic or strength properties of Ni-based cast superalloys becomes possible. Introduction of 0.01 % of synthesized grain refiner during the casting of SM88U (СМ88У) superalloy allows decreasing mean grain size from 1…2 mm to 0.2…0.5 mm. Tensile strength of inoculated superalloy at the temperature of 900˚С was 68 MPa while their stress rupture strength increased by 20 % in average. Composition and properties of inoculated alloys comply with standard technical documentation, which allows their usage for the
    production of gas turbines blades.


    Synthesis and design of hyperboloid gear drives: Methodology and aspects

    Machines. Technologies. Materials., Vol. 13 (2019), Issue 7, pg(s) 285-290

    The high current requirements for the characteristics determining the accuracy, reliability and efficient manufacturing of modern machines, apparatus and devices applicable in various fields of industry and transport in a big extend dictate the applied scientific methodology to the technological synthesis, design and production of gears. In the processes of synthesis and design of the different types of gear transmissions, the designer faces an extremely complex set of questions to solve, which together define the desired optimal construction.
    In this case, an optimal design means a gear transmission that is capable of delivering preliminary defined kinematic and / or strength requirements at minimum design, production and operation costs (including the repair costs during their exploitation). This work presents a review of the methodology, developed by the authors, oriented towards the synthesis and design of spatial gear mechanisms (hyperboloid gear drives), realizing rotations transformation between crossed shafts. The main principles, on which the construction of adequate software programs are based for the synthesis of treated transmissions, are presented.

  • Peculiarities of the structure formation of materials of Al-Cu and Al-Cu-C systems under the conditions of sparkplasma sintering

    Materials Science. Non-Equilibrium Phase Transformations., Vol. 4 (2018), Issue 2, pg(s) 41-44

    The features of the structure formation of Al-Cu and Al-Cu-C materials under conditions of spark-plasma sintering under conditions of superposition of a direct and pulsating current at a temperature of 600ºC and a mechanical pressure of 60 MPa are studied. The obtained Al-Cu-C system materials with hardness from 400 to 1000 MPa, porosity from 3 to 1% are recommended for use as slip contacts, and also as antifriction materials in friction pairs either in dry (carbon-containing composites) or wet friction (composites not containing carbon).

  • High-energy synthesis of metalomatric composites hardened by max phases of Ti-Al-C system

    Machines. Technologies. Materials., Vol. 12 (2018), Issue 10, pg(s) 395-397

    The possibility of synthesizing the Ti3AlC2 and Ti2AlC MAX phases by SPS (spark-plasma sintering) consolidation of the charge obtained as a result of mechanoactivation and a charge obtained by HVED (high-voltage electric discharge) of processing titanium and aluminum powders in kerosene has been experimentally studied. The influence of the charge activation method on phase formation and physical properties of consolidated materials is shown.


    Machines. Technologies. Materials., Vol. 12 (2018), Issue 7, pg(s) 302-304

    Compositions of the products of the electrolysis of melts based on a eutectic mixture of sodium chloride–lithium fluoride and sodium tungstate, which contains molybdenum (VI) and tungsten (VI) oxides, molybdates, tungstates, and carbonates of lithium or sodium, are investigated. It is shown that, depending on the content of melt components, the products of electrolysis are carbon, molybdenum, tungsten, and their bronzes and carbides. The conditions of the deposition of galvanic coatings of molybdenum and tungsten carbides on carbon, nickel, and copper matrices are determined.