Machines. Technologies. Materials.
Vol. 15 (2021), Issue 7

Table of Contents

  • MACHINES

    • The immovable mixers for the dosing of the substrate on the biogas plants

      pg(s) 252-255

      In this paper the solutions, types and groups of immovable mixers for the dedicated biogas power plants, as well as the connections (calculation) of the pipes for the transport of the substrata from the mixer to the digester are presented.
      The continuous feeding on biogas devices represents the challenge with which every producer of the electricity, more precisely, of the biogas device, is faced.
      Apart from numerous research, the feeding with the immovable mixers for the dosing of the mass, turned out to be an adequate and the most economical solution.
      The using of the immovable mixers with the direct inserting of the mass into the digester represents the most effective way of feeding the biogas devices which have the need for the solid matter and it does not have the liquid preparation. The new way of feeding is ideal for the biogas devices which have diagonal mixers in the digesters and which can follow the dosing of the immovable mixers.

    • Thin layer activation method. Potential applications and benefits for the food processing industry

      pg(s) 256-258

      Mechanical wear, corrosion and erosion of the structural materials in machines and apparatus are destructive processes which cause worsening of their basic operational characteristics throughout their life cycle. As a result, the technological equipment undergoes loss of efficiency and reliability. It becomes unsafe from hygienic point of view. The expenses needed for its maintenance in crease significantly as the time passes. Its economical efficiency decreases as well. Materials which are in direct contact with food products can also transmit metallic ions or low molecular compounds to the processed food products – a process which is known as “migration”. Thin Layer Activation (also known as Surface Layer Activation) is an unique, efficient and innovative radiation based method used for conducting of comprehensive studies on surface degradation of materials. It allows real-time measurements of wear intensities with exceptionally high sensitivity within the scope of several ηm/h (or μg/h). The article reviews the essential principles of the Thin Layer Activation Method (TLA Method), describes its applications, capabilities and advantages. Possible uses in food processing industry are assessed and potential benefits from its implementation are discussed. Technological equipment in food processing industry includes machines and apparatus for production and processing of food products and liquids, packaging equipment, sanitation equipment, equipment for refrigeration and maintaining of certain environmental conditions, transportation equipment and auxiliary tools and equipment.

  • TECHNOLOGIES

    • Pitting factor in use of galvanostatic pulse method for measuring the corrosion rate of reinforcement in concrete

      pg(s) 259-263

      Corrosion of steel reinforcement in concrete is the most common cause of deterioration of reinforced concrete structures which ultimately leads to structural failure. Maintenance and repair of concrete structures exposed to corrosion of reinforcement causes high costs worldwide. The simplest and at the same time practical mathematical model of corrosion degradation of reinforced concrete structures is to determine the remaining diameter of reinforcing bars based on the depth of corrosion penetration. The real depth of corrosion penetration differs from the corrosion depth that can be determined from the measured corrosion rates. To establish a relationship between the corrosion depths determined from measured corrosion rates and real depths of corrosion penetration, it is necessary to determine the socalled pitting factor. This paper will present the values of pitting factors for hot rolled and cold worked steel reinforcement bars embedded in concrete beam and slab specimens, using the galvanostatic pulse method and GalvaPulse measuring equipment.

    • The application of rapid prototyping in the studing of samples of filtering materials based on woven nets

      pg(s) 264-266

      In the paper consider materials for the rapid prototyping (RP) of experimental samples of filtering materials with an orthotropic structure based on woven nets (FMWN) assembled together with test-form and with using of 3D printing. RP made it possible to reduce the labor intensity of the process, primarily by eliminating the operation of sealing samples when using a traditional test form, as well as making the test form and the samples themselves. The data obtained allowed us to conclude that the use of 3D-printing is promising in further work for the manufacture of test form for studying the properties of filtering materials.

    • Testing of technology for joining materials in the automotive industry

      pg(s) 267-270

      Research on composite materials is nowadays developed on a global scale, because they have multipurpose applications. Composite materials are used in a wide range of industries. The most significant advantages of composite materials include st rength, stiffness, low fibre density (e.g. carbon fibre or glass fibre), the ability to make them into any shape required for the application. The paper deals with the possibilities of joining composite materials with metallic materials. The experimental part includes tests of the strength of the chosen type of adhesive and comparison of the individual results obtained by the experiment.

  • MATERIALS

    • Estimation of the elasticity module of Al-Si alloy samples in cast and deformed states by the frequency spectrum of sound vibrations

      pg(s) 271-274

      Using fast Fourier transform the frequency spectra of sound vibrations of sound obtained by impacting a suspended material sample were obtained and analyzed. For this, the corresponding short sound files were recorded, which were then subjected to computer analysis. It was found that the frequency spectra of sound vibrations for cast silumin and for those after deformation-heat treatment have a different character. So in these spectra obtained for samples that have passed the deformation-heat treatment, a set of narrow, clearly peaks at certain frequencies have been observed. In the spectra obtained for cast samples, such clear, narrow peaks are not observed. The position of the characteristic peaks in the frequency spectra of sound vibrations was used to estimate the elastic modulus for samples that have passed various regimes of deformation-heat treatment.

    • The nanostate factor in the technology of polymer nanocomposites

      pg(s) 275-278

      Methodological approaches to the implementation of the nanostate phenomenon in the formation of the optimal structure of composite materials and metal-polymer systems at different levels of organization have been developed. The concept of energy and technological compliance of functional composite materials and systems components, which determines the optimal parameters of stressstrain, adhesion and tribological properties under technological influences on the components in the process of obtaining composite and its processing, is proposed.

    • State and prospects of application of plastically deformed nanostructured metals, alloys, and sprayed coatings

      pg(s) 279-282

      It is shown that thermal stabilization of the polygonization substructure up to 60 min is provided by a combination of uniaxial compressive deformations, namely dynamic by 30% and static by 30%, followed by pre-recrystallization heat treatment (PHT) at the initial recrystallization temperature. This ensures subgrain size of 80… 187 nm, while strength characteristics increase by 10… 30% with sufficient ductility.
      It is shown that PHT provides the formation of nanoscale elements in electric arc coatings with Sv-08G2S (Св-08Г2С), and additional deformation of the coating allows to increase the thermal stability of the polygonization substructure up to 40… 50 min. It is found that the combined deformation and subsequent PHT of steels provides an increase in the calculated number of nanoscale subgrains from 15 to 65%.

    • Investigation of the causes of corrosion of galvanized steel pipes used for hot water supply

      pg(s) 283-286

      The object of the study is the part of the galvanized steel pipe (about 1-meter-long) supplied by the customers, which was used to supply hot water inside the residential building and which has corroded during exploitation of 5 years. To clarify the situation, quality of surface coating and microstructure of the obtained galvanized steel pipe was analysed. Electrical stray currents of the pipeline installed in the building were measured. The sample of the hot water was taken and analysed at the certificated laboratory.
      The aim of the investigation was to determine the possible causes of the hot water supply pipe corrosion during sufficiently short time of exploitation.

    • Recent applications of nanoparticles in wood-based panels

      pg(s) 287-290

      Nanocellulose applications in the wood-based panels have gained a great deal in the scientific researches and industrial applications. Utilization of natural and synthetic nanoparticles as reinforcement in the wood-based panels has considerably increased in the last two decades due to their unique properties. The main property of the nanocellulose is its very high surface area. Hereby, the very small use of nanoparticles suh as %1-2 wt% in the composites is enough at a relatively low-cost. Nanoparticles are presently considered to be high-potential reinforcing fillers for the enhancement of the physical, mechanical, electrical/electronic properties, thermal resistivity, fire, durability properties of wood-based panels such as particleboard, fibreboard, oriendted strandboard, and plywood. The nanoparticles are applied to wood based panels dur ing the manufacture and after production. The raw materials such as wood or resin can be treated with nanoparticles or the finished panels can be treated with nanoparticles. In this study, the recent developments in the nano particles, their applications in the wood based panels, and their effects on the panel properties were reviewed