Litteris et Artibus
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Item Structure and properties of dielectric coatings based on fusible glass-ceramic materials(Lviv Polytechnic Publishing House, 2016) Kovbasyuk, Taras; Klymko, Orest; Baziuk, Mychailo; Lviv Polytechnic National UniversityStructure and thermal properties of the dielectric coatings on the basis of glass-ceramic system PbO-ZnO-B2O3-SiO2-Al2O3-BaO (sealant) on a stainless steel substrate were studied. The advantages and disadvantages of these surface layers in comparison with dielectric surface layers applied according to the method of magnetron sputtering are shown.Item Tribotechnical characteristics of VT22 titanium alloy after nitriding, combined with heat treatment(Lviv Polytechnic Publishing House, 2016) Lavrys, Serhii; Kovbasyuk, Taras; Penkovyi, Oleh; Karpenko Physico-Mechanical Institute of the NAS of Ukraine; Lviv Polytechnic National UniversityNitriding of VT22 titanium alloy, combined with its standard heat treatment in a single technological cycle was proposed. It was shown that after thermodiffusion saturation the microhardness and depth of the hardened surface layer of VT22 alloy increased, but the quality machined surface worsened. It was established that the increase time of nitriding process worsened the tribotechnical characteristics of friction pair nitrided VT22 alloy – BrAZhN 10-4-4 bronze.Item Rheological properties of compositions based on modified polyvinyl alcohol(Видавництво Львівської політехніки, 2017-12-23) Antoniuk, Viktoria; Krasinskyi, Volodymyr; Khamula, Natalia; Yurkiv, Iryna; Lviv Polytechnic National UniversityDeveloped of a method for producing structured waterproof films based on polyvinyl alcohol (PVA) and montmorillonite-polyvinylpyrrolidone mixture (MPM) to research the impact of borax, pH-environment and MPM content on the rheological properties PVA solutions and water absorption capacity of films based on them. The MPM mixture significantly affects on viscosity the characteristics of the solution polyvinyl alcohol provided their mixing in the ultrasonic field have been established. Composition of traces of sodium tetraborate in the aqueous solution eminent by the highest rates of viscosity. Also, designed compositions considerable influence pH at the viscosity, particularly compositions obtained in weakly alkaline environment with higher values of relative viscosity than compositions obtained in neutral and acidic environments.Item Effect of heat treatment on brewer's yeast fermentation activity(Lviv Polytechnic Publishing House, 2015) Kharandiuk, Tetiana; Kosiv, Ruslana; Palianytsia, Liubov; Berezovska, Natalia; Lviv Polytechnic National UniversityThe influence of temperature treatment of brewer's yeast strain Saflager W-34/70 at temperatures of -17, 20, 25, 30, 35, 40 °C on their fermentative activity was studied. It was established that the freezing of yeast leads to a decrease of fermentation activity in directly proportional to the duration way. Fermentative activity of yeast samples can be increased by 20-24% by heat treatment at 35 °C during 15-30 minutes.Item Thermo-kinetic properties of the new materials for functional layers of flat heating elements(Lviv Polytechnic Publishing House, 2015) Kovbasyuk, Taras; Shapran, Yuliia; Lviv Polytechnic National UniversityThermokinetic properties of the dielectric coatings on the basis of glass-ceramic system PbO-ZnO-B2O3-SiO2-Al2O3 (Sytal-Tsement) on a stainless steel substrate were studied. The advantages and disadvantages in comparison with modern functional layers of flat heating elements were analyzed.