Materials Engineering 2017

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Authors: Laura Rozenberga-Voska, Jānis Grabis
Abstract: TiO2 and silver doped TiO2 thin films were prepared by spray pyrolysis technique and their photocatalytic activity were determined. Titanium(IV) isopropoxide solution or its mixture with silver nitrate were used as precursors. As-prepared at 300 °C films were X-ray amorphous. Calcination of the films at 500 °C for 5 – 6 hours allowed to obtain partially crystalline anatase films with uniform grain size in the range of 80 – 150 nm. Degradation degree of MB water solution by using TiO2 and TiO2/Ag photocatalysts under UV irradiation reached 60 and 70 % respectively.
Authors: Zane Grigale-Soročina, Ingmārs Birks, Mārtiņš Kalniņš
Abstract: This report explores two key manufacturing processes, and assesses multiple parameters for optimization of these processes. High shear dispersion using a rotor-stator style homogenizer and high-energy grinding using a basket type mill with zirconium balls as the grinding media were studied. The variation between grinding organic and inorganic pigments was assessed as they give different challenges and require different operations to produce successful results. Obtaining the correct particle size distribution of pigments for decorative coatings is of paramount importance for achieving a high quality, functioning, aesthetically pleasing finished product. This analysis will explore the de-agglomeration and dispersion of inorganic TiO2 and organic Red 6 pigments using basket milling technology. High energy basket mill grinding produced the smallest particle size and smallest particle size distribution comparing with high shear dispersion. Used technology allowed to achieve inorganic pigment TiO2 particle size and particle size distribution suitable for use in coatings on natural nails. For organic pigment Red 6 used technology should be customized.
Authors: Marianna Laka, Marite Skute, Sarmite Janceva, Velta Fridrihsone, Inese Sable, Linda Vecbiskena, Uldis Grinfelds, Laura Andze, Juris Zoldners
Abstract: For reinforcing of paper, nanoparticle gels from black alder, birch and pine bark were obtained. Non-extracted bark and that extracted in biorefinery were used. For producing nanoparticles, the materials were destructed using the thermocatalytic destruction method and then dispersed in water medium in a ball mill. At a sufficient concentration, gel-like dispersions were obtained, which contained nanoparticles with the size ~300 nm. The effect of nanoparticle gels on the properties of paper sheets was investigated by introducing the dissolved gels in paper furnish and by covering both sides of paper sheets with nanoparticle gel coatings. It has been established that the nanoparticle fillers increase the tensile and burst strength. The nanoparticle fillers from extracted bark increase the mechanical indices to a higher extent. The coatings from nanoparticle gels considerably improve the Gurley air resistance of paper and increase the mechanical indices of paper sheets, especially burst strength. The effect of nanoparticle gel coatings is dependent on the coating thickness and gel concentration. The coatings decrease the tensile strength in a wet state.
Authors: Viesturs Zeltins, Vladimir Yakushin, Ugis Cabulis, Mikelis Kirpluks
Abstract: The synthesis technology of polyol from crude deciduous tree tall oil was developed, the structure of obtained polyol was analyzed using FTIR spectroscopy. Compositions of rigid polyurethane (PUR) foams were formulated using polyol from crude deciduous tree tall oil, Isocyanate indexes varied in wide range from 150 to 300. The densities of obtained rigid polyurethane foams was in range from 44-101 kg/m3. Produced rigid PUR foams were characterized by good compression characteristics and low water absorption. The optimal water absorption was achieved at density lower than 50 kg/m3 and Isocyanate index lower than 175. Thus the obtained PUR foams have the potential to be used for boat construction or for production of life-saving equipment.
Authors: Fırat Durmuş, Mürsel Ekrem
Abstract: In this study, the production of weight ratios of 1, 3 and 5 % multi-walled carbon nanotubes (MWCNT) reinforced / unreinforced Nylon 6,6 (N-6,6) nanofiber mats was carried out by electro spun method. Tensile strength (sT), modulus of elasticity (E), toughness and elongation amounts were investigated by tensile tests under static loading with / without reinforced nanofiber mats. % 3 MWCNT reinforced N-6,6 nanofiber mats, tensile strength, E and toughness increased by 84.4, 235 and 112 %, respectively, when compared with N-6,6 nanofiber mats. In addition, scanning electron microscope (SEM) images were also investigated to determine the physical properties at the specification of reinforced /unreinforced N-6,6 nanofiber mats.
Authors: Ritvars Berzins, Remo Merijs Meri, Janis Zicans
Abstract: Two component model systems from Silyl-terminated polyether (SAX 520) and epoxy resin (D.E.R. 331) can produce higher mechanical properties than each system individually. This work is dedicated to explore two components (SAX 520/D.E.R. 331) systems and represent their benefits comparing to neat SAX 520 based system. Work shows that compositions with epoxy resin not only improves material mechanical properties, but also its stability after aging, workability time and adhesion on various substrates.
Authors: Emrah Madenci, Atilla Özütok
Abstract: The main objective of the present study is to give a systematic way for the derivation of laminated composite plates by using the mixed type finite element formulation with a functional. The first order shear deformation plate theory is used. Differential field equations of composite plates are derived from virtual displacement principle. These equations were written in operator form then by using the Gâteaux differential method, a new functional which including the dynamic and geometric boundary conditions is obtained after provide potential conditions. Applying mixed-type finite element based on this new functional, a plate element namely FOPLT32 is derived which have 8 degrees of freedoms on per node, total 32 freedoms. The reliability of the derived FOPLT32 plate elements for static analysis is verified, since the results obtained have been shown to agree well with the existing ones.
Authors: Darius Pauliukaitis, Edmundas Kibirkštis
Abstract: Pneumatic vibroexciters which consist of smart materials’ structural elements and are operating under autovibration regime were designed. The chamber of vibroexciter actuator with changeable capacity for flowing pressured air made of shape memory alloy (SMA) were presented. Mechanical characteristics of such type vibroactuator were estimated: maximum deformation of structural element with SMA, possible force of martensitic transformation. The result of the research allows to design functional adaptive pneumatic vibroexciters with are suitable for the different purposes of technological processes.
Authors: Sinan Sezek, Bunyamin Aksakal
Abstract: In this study, temperature distribution that occurred during cold and hot rolling of AA5454-O alloy has been investigated. Temperature variation taking place in the aluminium alloy that has undergone plastic deformation between the rollers during hot and cold rolling process is of major importance in terms of determining the positive and negative characteristics or features which such temperature variation adds to the formation of the internal structure of the material concerned. Temperature distribution has been measured by use of the installed laboratory equipment and respective data recorded has been presented in the form of graphic charts. Temperature distribution has varied depending on the application of hot or cold rolling process and it has been noted that variations in terms of temperature reduction took place depending on the number of roll passes. While average temperature variation has occurred as a 16°C increase in the case of cold rolling, it has been observed that such variation appeared as a 100°C decrease on the average in the case of hot rolling.

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