The use of structures made of titanium and its alloys, which have improved corrosion, physical and mechanical properties, are in demand in many industries. In this regard, the processes of modifying the surface of metals are of interest. One of the modern and promising methods of metal surface treatment is plasma electrolytic oxidation. Currently, there is a problem of widespread use of this process when DC modes are used in the implementation of the process. This is due to the large consumption of electricity. The purpose of this work is to study the morphological and corrosion properties of oxide coatings obtained in the pulsed anode-cathode mode on titanium alloys VT1-0 and VT5 in various electrolyte solutions. Modification of the surface of titanium alloys was carried out at the duration of the anode current pulse of 250 ± 25 microseconds, the duration of the cathode current pulse of 5 ± 0.5 ms, the repetition frequency of the anode and cathode pulses of 50 ± 0.5 Hz. Alkaline solutions served as electrolytes. Oxide coatings obtained in various electrolytes are characterized by different porosity and coating thickness. Coatings with a finely porous structure, with an average pore diameter from 0.09 microns to 0.4 microns, and larger pore sizes of 0.6 – 0.7 microns were obtained. The porosity of the coatings ranges from 6.12% to 12.2%. According to the data of energy dispersion analysis, it was found that the structure of oxide coatings includes both components of the processed metal and components of the electrolyte solution. The main components, in this case, are oxygen and processed metal, as well as other elements such as boron, phosphorus, aluminium, fluorine, sodium, silicon and others. Corrosion tests according to GOST 9.308-85 under the influence of neutral salt mist at a temperature of (35 ± 2) °C with 1500 hours in the Ascott CC 450 chamber, it was shown that there was no corrosion damage to the coatings.
В ходе исследовательской работы проанализированы способы получения целлюлозы из недревесного растительного сырья. Отработана технология получения целлюлозы высокого выхода сульфатным способом из мискантуса, пригодной для использования в композиции компонентов тарного картона. Условия получения целлюлозы высокого выхода: расход активной щелочи – 7%, температура – 150 °С, продолжительность – 30 мин, гидромодуль варки – 5, продолжительность горячего размола – 5 мин. Отработана технология получения химико-термомеханической массы из сечки. Условия получения: расход активной щелочи – 3%, продолжительность пропитки при 90 °С – 10 мин, продолжительность обработки при 120 °С – 10 мин, гидромодуль – 5. Отработан технологический режим отбелки химико-термомеханической массы из мискантуса по укороченной схеме Х – ЩП1 – ЩП2 с расходом Н2О2 60 кг/т, белизна образца составила 55% ISO. Отработана технология получения нейтрально-сульфитной полуцеллюлозы из мискантуса, пригодной для использования в композиции компонентов тарного картона. Условия получения нейтрально-сульфитной полуцеллюлозы: расход активной щелочи – 20%, температура – 175 °С, продолжительность – 50 мин, гидромодуль варки – 7, продолжительность горячего размола 5 мин. В соответствии с полученными результатами можно сделать вывод о том, что мискантус может быть использован для получения аналога лиственной сульфатной целлюлозы для применения в композиции различных видов бумаг. In the course of the research work, methods for obtaining cellulose from non-wood plant raw materials were analyzed. The technology of obtaining high yield cellulose by sulphate method from miscanthus, suitable for use in the composition of container cardboard components, has been developed. Conditions for obtaining high yield cellulose: active alkali consumption –7%, temperature-150 °C, duration – 30 minutes, cooking hydromodule – 5, duration of hot grinding – 5 minutes. The technology of obtaining a chemical-thermomechanical mass from a cross-section has been worked out. Production conditions: active alkali consumption – 3%, impregnation duration at 90 °C – 10 min, processing duration at 120 °C – 10 min, hydromodule – 5. The technological mode of bleaching the chemical-thermomechanical mass from miscanthus according to the shortened scheme Q – P1 – P2 with a consumption of H2O2 of 60 kg/t, the sample whiteness was 55% ISO. The technology of obtaining neutral-sulfite semi-cellulose from miscanthus, suitable for use in the composition of container cardboard components, has been developed. Conditions for producing neutral-sulfite semicellulose: active alkali consumption – 20%, temperature – 175 °C, duration – 50 minutes, cooking hydromodule – 7, duration of hot grinding – 5 minutes. In accordance with the results obtained, it can be concluded that miscanthus can be used to obtain an analog of leafy sulphate cellulose for use in the composition of various types of papers.
The article presents the results of numerical research on finite-element models of flat girderless floors. The influence of geometric parameters on the magnitude and ratio of force factors that occur during the operation of a flat reinforced concrete slab was studied. Force factors include the combined action of the punching force and the bending moment. The variable parameters in the study were the flexibility of the column and the size of its cross-section. The purpose of the study was to substantiate the ratio of the bending moment and the longitudinal force in the column for the development of methods for conducting experimental studies on test samples. Based on the results of the study, the influence of the column’s flexibility and the dimensions of its cross-section on the ratio of the studied force factors was established. The study made it possible to choose the best option for loading test samples. The results of the study were used to conduct experimental studies on the punching of flat reinforced concrete slabs.
currently, the development of biomaterials that have the required characteristics for various tissues is one of the main problems in medicine and engineering. Obtaining calciumphosphate coatings on metal surfaces is one of the urgent problems in materials science. Nevertheless, there is no unambiguous data on what physicochemical properties (phase and elemental composition, structure, crystallinity, roughness, solubility, etc.) should have an implant surface that ensures its osseointegration. In this work, to obtain calcium-phosphate coatings, we used the method of detonation-gas spraying of powder materials on a Grade2 titanium base. A TiAl 3 mixture with the addition of calcium hydroxyapatite was used as powder materials. The mass percentage of TiAl 3 in the mixture was 40%, 55%, 65%, 80%. The topography of the coating surface was determined by computer three-dimensional modeling based on data obtained using a Zygo New View 7300 interferometer-profilometer. It was found that with an increase in the intermetallic content in the TiAl 3 mechanocomposite with hydroxyapatite ( Ca 10 (PO 4 ) 6 (OH) 2 ), the layer roughness of the surfacing of composite materials increases from Ra = 2.628 µm to Ra = 3.490 µm . At the same time, the roughness of the layer has an important role in the growth of bone tissue. Comparative analysis of the dependence of bone tissue growth on the roughness of coatings showed that layers obtained by detonation-gas spraying based on hydroxyapatite have a higher efficiency of about 100% of bone tissue growth at roughness values Ra = 2-4 µm .
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