Table of Contents


    • Visualization and analysis of worm gear drives efficiency and load capacity

      pg(s) 50-53

      Scientific methodologies have been created and applied during the analysis upon worm gear drives. Important parameters have been selected in order to make significant investigations in the area of worm gear efficiency and load capacity. The efficiency coefficient and maximal torque values have been studied for several combinations of modules, ratios, center distances, etc. The results have been presented and analysed through three-dimensional graphics. Conclusions are made.

    • Design and CFD simulation of the exhaust manifold of the Formula Student vehicle

      pg(s) 54-57

      One of the biggest challenges in the FSAE competition is adapting the power unit to the strict regulations of the competition. The task of the exhaust manifold is to enable the best possible flow of exhaust gases from the engine to the environment. A properly designed vehicle exhaust manifold is of great importance for enabling better performance of the power unit. There are several different concepts for designing exhaust manifolds. Each concept has its advantages and disadvantages. One of the main guidelines when designing the exhaust manifold is to enable air flow with as little local resistance as possible so that the exhaust gases are released into the environment as soon as possible. In this work, a 3D model of three types of exhaust manifolds was created, and then a CFD simulation of airflow through exhaust manifolds was performed using ANSYS Fluent software. CFD simulations help to a great extent with a better design of the exhaust manifold.


    • Influence of the window profile on the final quality of the product

      pg(s) 58-63

      The current product on the market offers a wide range of diverse profiles for producing windows that are made of different materials, width and order of grills depending on the profile. Within the framework of this research the windows with same dimensions shall be elaborated, those which are made of the same production capacity and use the same fittings but different types of PVC profiles. The aim is to prove what kind of influence the used profile has over the final quality of the product. For this research, two groups and six subgroups will be tested. In each subgroup, one tests five windows made of the same profile. The groups are divided according to the used fittings. The testing of the quality shall be conducted in accordance with the European norms EN 1026:2016 (Windows and doors – Air permeability – Test method), EN 1027:2016 (Windows and doors – Water tightness – Test method), EN 12211:2016 (Windows and doors – Resistance to wind load – Test method).

    • Study of Vitamin C stability in thermal water for ecofriendly application in the pharmaceutical industry

      pg(s) 64-66

      Free radicals and reactive species of oxygen are destructive for living organisms. Antioxidants are capable to reduce the effect of free radicals and to recover the organisms’ health. On the other hand, during the fabrication process various chemicals are released into the water ecosystems from the factories, causing harmful effects on the aquatic organisms. The Autonomous Province of Vojvodina in Serbia is rich in thermal waters. Thankfully to the various minerals, they could have antioxidant effect and could be used as raw material for the production of different pharmaceutical products. In this study we examined the possible effect of different thermal water samples on the degradation rate of Vitamin C as an antioxidant with UV radiation. Furthermore, the influence of initial pH value was also investigated. Our results showed that the thermal water reduced the degradation rate of vitamin C. In addition, the lowest removal rate was observed at initial pH 7, which is close to the skin’s natural pH. These findings showed that the thermal water could be used in preparations for skin.

    • Studying the surface and microstructure of a chromium coating with nanodiamond particles deposited on monolithic composite with layered structure

      pg(s) 67-69

      Electrochemical coatings of chromium modified with nanodiamond particles applied directly on niobium-aluminum alloy were obtained. Nanodiamond particles produced by detonation synthesis were used. Chromium coatings were deposited on a monolithic composite with a complex structure based on niobium and aluminum alloys, called later matrix for short. Standard chromium electrolyte and electrolyte with nanodiamond particles concentration of 10 g/l were used. Analyzes were performed by Scanning Electron Microscope system of Bruker Inc. and the Polyvar Met metallographic microscope. The microhardness was measured using a PolyvarMet 4000 microhardness tester. The obtained results of the microhardness were 788 kg/mm2 in the chromium layer and 168 kg/mm2 and 692 kg/mm2 in the matrix. The microstructural and SEM-EDS analysis showed the presence of two intermetallides Nb2Al and Nb3Al in the monolithic composite of niobium aluminum matrix. The average thickness of the chromium coatings modified with nanodiamond particles is 55 μm.

    • Formation of the structure of polymeric products on the based of polyamide 6 produced by fdm-printing

      pg(s) 70-72

      An analysis of the prospects for the development of FDM printing technology has been carried out. The paper studies the possibility of obtaining polymer products based on polyamide 6 and its compositions by layer-by-layer deposition. Tests of the strength indicators of the printed experimental products were carried out. The mechanism of the influence of the composition and modes of formation of printed products on their strength characteristics is proposed. The influence of the composition of the composite polymer material based on PA6 on the quality of printing products has been studied. Methods for controlling the shrinkage parameters of products obtained by
      layer-by-layer deposition are proposed. The obtained results of the study can be used in the development of composites for the production of polymer filament to ensure the process of FDM printing of polymer products, including for the needs of mechanical engineering.

    • Technology and technological scheme of a workshop for the production of beehives made of amorphous quartz ceramics

      pg(s) 73-75

      The development refers to an innovative technology and technological scheme of a workshop for the production of beehives made of amorphous quartz ceramics. The conditions for obtaining stable suspensions from quartz glass are emphasized and investigated. The time for the treatment of the glass in the grinding device, the amount of water, the influence of the modifiers in stabilizing the suspension by adjusting the pH level, as well as the most suitable sedimentary composition of the glass particles are established. The factors determining the speed and degree of sintering of the ceramics are investigated and established. They include the density of the raw products, the dispersion of the quartz glass particles and its purity, as well as the environment in the furnace and the sintering mode.

    • Simulation of toolpaths and program verification of a CNC lathe machine tool

      pg(s) 76-79

      This paper presents the simulation and verification of programs created for the CNC Hitachi Seiki Seicos LIII lathe machine tool. The main purpose of program simulation and verification is to ensure the quality and accuracy of the cutting process, which can significantly improve production efficiency. In addition to defining the toolpath, simulation can perform linear and circular interpolation according to specific programs based on G – codes. Therefore, all the motions of the moving parts of the real lathe machine tool can be clearly visualized. The use of simulation is a good solution not only to precise the toolpath, but also verify the program and detect any possible collision between cutting tools and mobile components, before loading the program into the lathe machine tool and starting cutting processes.

    • Analyze of welding arc parameters in shielded metal arc welding

      pg(s) 80-82

      Shielded metal arc welding is widely used in heavy industries in partly shipbuilding and ship repair. This method didn’t required special personal skills and equipment. Different scientists are analyzed welding parameters, mechanical characteristics and chemical composition in welding seam but interesting is to be investigated welding arc characteristics in different electrodes. The paper deal with analyze of welding arc parameters in shielded metal arc welding. For this purpose on mild steel plates are welded seams with different diameters of electrodes and different welding current. In welding process are measured welding arc burning time, length of electrodes melted part, welding machine voltage and weight of melted electrodes part. For analyze welding arc parameters are used response surface methodology method (RSM). Used RSM in the paper is 2k factorial design where k=2 factors. The influence of each to other factors of welding arc is presented by meta models.


    • Physico-chemical characterization of the corn silk by DTA-TGA, SEM-EDS and FTIR analysis

      pg(s) 83-85

      In this paper, the results of the DTA-TGA, SEM-EDS, and FTIR analysis of the corn silk are presented. The DTA-TGA analysis shows that the decomposition of corn silk has several stages which are manifested with corresponding peaks on obtained DTA-TGA curves. SEM-EDS analysis was performed before and after the adsorption of copper ions. It has shown that untreated corn silk has a non-uniform structure, consisting of channels and cavities of irregular orientation, which facilitates the penetration of the water phase into the adsorbent structure, and incorporation of copper ions in the internal active sites. After the adsorption of Cu2+ ions, the structure becomes more compact, and uniform, as a result of the incorporation of copper ions into the molecular structure of the corn silk. FTIR analysis shows that ion exchange is not the dominant mechanism of binding copper ions to the active sites in the molecular structure of the corn silk, but also chemisorption and physical adsorption is present.

    • Application of characterisation methods in the development of biomedical titanium alloys

      pg(s) 86-89

      Biomaterials are becoming an increasingly important research topic over time as they are used to replace parts and functions of the human body, helping to improve the quality of human life. Titanium alloys are particularly important for the development of new biomaterials. Commercial pure titanium and its alloys are used as essential structural biomaterials in the manufacture of implants due to their excellent biocompatibility, good corrosion resistance and mechanical strength. However, studies have shown that aluminum and vanadium ions are released in alloys such as Ti-6Al-4V, which can cause health problems over time. Because of the problems that occur, researchers are working to improve the properties of titanium alloys by adding new elements. In most cases, different metals are added to titanium and it is known that with the presence of different metals, the properties of titanium also change. All biomedical titanium alloys must undergo various testing procedures before they can be used. The article describes the characterisation methods used in the development of titanium alloys, such as: light and scanning electron microscopy, energy-dispersive spectrometry, X-ray diffraction analysis, differential scanning calorimetry, differential thermal analysis. The reliability of the results depends on the methods used and the avoidance of errors in the characterisation of biomedical alloys in order to reach better conclusions and produce alloys of the highest quality desirable for use in the human body.

    • The influence of electrochemical corrosion on the structure and phase composition of a sintered multicomponent titanium-based composite in a 3% NaCl solution

      pg(s) 90-92

      The electrochemical corrosion properties in a 3% NaCl solution of the titanium-based multicomponent composite of the 65TiH2–30FeSiMn–B4C system were investigated. The kinetics and the mechanism of anode dissolution of metals and oxidation of specimens have been studied by using polarization curves, chemical and x-ray phase analyses. It was found a decrease in the titanium carbide peaks on the X-Ray defractions also the titanium silicon carbide almost disappears after immersing the sample in a 3% NaCl solution. Formation of silicon and boride phases of titanium in the synthesis process leads to an increase in corrosion resistance due to the inhibition of the velocities of both the anode and cathode processes.

    • Composite graphene/nanocarbons prepared by one-step reduction reaction

      pg(s) 93-95

      Nowadays, the decrease of CO2 concentration in the atmosphere and/or its utilization need urgent resolution. At the same time, preparation of advanced graphene-based composites through effective environmentally benign procedures remains in the focus of intensive research. In the present work, composites consisted of reduced graphene oxide and nanocarbons (rGO/nC) were prepared by simultaneous reduction reaction of solid graphite oxide and CO2 gas over alkaline earth reductant. The structure and the morphology of the prepared composite material were examined employing X-ray diffraction analysis and scanning electron microscopy. It was revealed that the characteristic narrow peak of the graphite oxide (GtO) at low 2θ (~11o) was not present in the pattern of the composite suggesting its successful reduction. Instead, a broad one positioned at 26o was recorded which was attributed to the formed nanocarbons. The observed accordion-like morphologies typical for reduced-graphene-oxide type of graphene evidenced the detachment of the graphene layers during the thermal treatment, while the formed nanocarbons were with irregular shape. The rGO/nC composite exhibited specific surface area (485 m2/g) higher than the pure nanocarbons (417 m2/g) obtained without addition of GtO. The outcome was attributed to the influence of the layered rGO which hinders the aggregation of the nanocarbons and facilitates their homogeneous distribution. The prepared composite can be considered as candidates for gas and energy storage applications, while the suggested environmentally benign preparation method can be scaled up to industrial extent due to simplicity.

    • Synthesis and characterization of 2D NbSe2

      pg(s) 96-97

      Two-dimensional van der Waals (vdW) materials possess novel physical properties and promising applications. A wide range of 2D vdW materials having been obtained via the chemical vapor transport (CVT) method. In this work, we develop the controllable growth meyhod of 2H-NbSe2 single crystals via the CVT method. The quality of fabricated crystals was characterized by X-ray diffraction, and electron dispersive spectrometry (EDS) measurements. Crystals of the best quality were successfully grown under selected temperature/time schedule.