ВЛИЯНИЕ ГЕОМЕТРИЧЕСКИХ РАЗМЕРОВ КАТОДА ВАКУУМНОГО ЭЛЕКТРОДУГОВОГО ИСПАРИТЕЛЯ ПЛАЗМЫ НА ВЕЛИЧИНУ ДОПУСТИМОГО ТОКА ДУГОВОГО РАЗРЯДА

An analysis of main design parameters that determine a level of droplet formation intensity at the generating stage of plasma flow has been given in the paper. The paper considers the most widely used designs of water cooled consumable cathodes. Ti or Ti–Si and Fe–Cr alloys have been taken as a material for cathodes. The following calculated data: average ionic charge Zi for titanium plasma +1.6; for «titanium–silicon plasma» +1.2, an electronic discharge 1.6022 ⋅ 10–19 C, an ion velocity vi = 2 ⋅ 104 m/s, an effective volt energy equivalent of heat flow diverted in the cathode Uк = 12 V, temperature of erosion cathode surface Тп = 550 К; temperature of the cooled cathode surface То = 350 К have been accepted in order to determine dependence of a maximum admissible arc discharge current on cathode height. The calculations have been carried out for various values of the cathode heights hк (from 0.02 to 0.05 m). Diameter of a target cathode is equal to 0.08 m for a majority of technological plasma devices, therefore, the area of the erosion surface is S = 0.005 m2.A thickness selection for a consumable target cathode part in the vacuum arc plasma source has been justified in the paper. The thickness ensures formation of minimum drop phase in the plasma flow during arc cathode material evaporation. It has been shown that a maximum admissible current of an arc discharge is practically equal to the minimum current of stable arcing when thickness of the consumable cathode part is equal to 0.05 m. The admissible discharge current can be rather significant and ensure high productivity during coating process with formation of relatively low amount of droplet phase in the coating at small values of hк.Проведен анализ основных конструкционных параметров, определяющих степень интенсивности формирования капель на стадии генерации плазменного потока. Рассмотрены наиболее широко используемые конструкции водоохлаждаемых расходуемых катодов. В качестве материала катодов брали Ti или сплавы Ti–Si, Fe–Cr. Для определения зависимости величины предельно допустимого тока дугового разряда от высоты катода были приняты следующие расчетные данные: средний заряд иона Zi для титановой плазмы +1,6, для плазмы «титан – кремний» +1,2; заряд электрона 1,6022 ⋅  10–19 Кл; скорость движения иона vi  = 2 ⋅  104 м/с; эффективный вольтовый эквивалент энергии теплового потока, отводимого в катод, Uк = 12 В; температура эродирующей поверхности катода Тп = 550 К; температура охлаждаемой поверхности катода То = 350 К. Расчет проводили для разных значений высот катода hк (от 0,02 до 0,05 м). Диаметр катода-мишени для большинства технологических плазменных устройств равен 0,08 м, следовательно, площадь эродирующей поверхности S = 0,005 м2.Теоретически обоснован выбор толщины расходуемой части катода-мишени вакуумного электродугового источника плазмы, при которой в процессе дугового испарения материала катода обеспечивается образование минимального количества капельной фазы в плазменном потоке. Показано, что при толщине расходуемой части катода hк, равной 0,05 м, величина предельно допустимого тока дугового разряда практически равна значению минимального тока устойчивого горения дуги. При малых hк ток допустимого разряда может быть значительным и обеспечивать высокую производительность процесса нанесения покрытий при образовании относительно низкого количества капельной фазы в покрытии

Push-Pull N,N-Diphenylhydrazones bearing bithiophene or thienothiophene spacers as nonlinear optical second harmonic generators and as photosensitizers for nanocrystalline TiO2 Dye-Sensitized solar cells

A series of push-pull heterocyclic N,N-diphenylhydrazones were prepared to study the effect of structural modifications (different pi-spacers and electron withdrawing groups) on the optical (linear and nonlinear) and electronic properties of the molecules.The photovoltaic response of DSSCs assembled using nanocrystalline titania photosensitized with the synthesized dyes was also studied. These heterocyclic push-pull conjugated dyes involve N,N-diphenylhydrazones as electron donors linked to bithiophene or thieno[3,2-b]thiophene spacers, and were functionalized with carboxylic acid, cyanoacetic acid, or dicyanovinyl acceptor groups. A combination of Suzuki-Miyaura cross-coupling, Vilsmeier formylation, and condensation reactions were used to synthesize the intermediates and final products. DFT and TDDFT calculations were used to obtain information on conformation, electronic structure and electron distribution, both for the free dyes and those adsorbed on TiO2. The results of this multidisciplinary study indicate that dyes 5b and 6b have the strongest second order nonlinear optical response with hyperpolarizability values in the range of beta = 2330-2750 × 10-30 esu, while photovoltaic power conversion efficiencies reach values in the range of 0.7-3.0 %, for dyes 5a-b and 7c that were enhanced by co-adsorbing DCA (0.8-5.1 %).Thanks are due to Fundação para a Ciência e Tecnologia (FCT) for a PhD grant to S.S.M.F. (SFRH/BD/87786/2012). To FEDER-COMPETE for financial support through the research center CQUM (UID/QUI/0686/2016). The NMR spectrometers are part of the National NMR Network (PTNMR) and are partially supported by Infrastructure Project no. 022161 (cofinanced by FEDER through COMPETE 2020, POCI and PORL and FCT through PIDDAC). The group in Coimbra is grateful for funding from Centro de Química de Coimbra which is supported by the Fundação para a Ciência e a Tecnologia (FCT), Portuguese Agency for Scientific Research, through the programmes UID/QUI/ UI0313/2013 and COMPETE. The authors also thank the Laboratory for Advanced Computing at the University of Coimbra for providing computing resources that have contributed to the research results reported in this manuscript. Thanks are also due to FCT for a postdoctoral grant to L.L.G.J. (SFRH/BPD/97026/2013). The group in Porto would like to acknowledge the European Commission through the Seventh Framework Programme, the Specific Programme “Ideas” of the European Research Council for research and technological development as part of an Advanced Grant under grant agreement no. 321315, which also partially funded this work. Some of this work was also performed under the project “SunStorageHarvesting and storage of solar energy”, with reference POCI-01-0145-FEDER-016387, funded by European Regional Development Fund (ERDF), through COMPETE 2020Operational Programme for Competitiveness and Internationalization (OPCI), and by national funds, through FCT.info:eu-repo/semantics/publishedVersio

РАЗРАБОТКА ПРОГРАММНОГО МОДУЛЯ ДЛЯ РАСЧEТА СКОРОСТИ ОСАЖДЕНИЯ ТИТАНОВОЙ ПЛАЗМЫ В СРЕДЕ ТЕХНОЛОГИЧЕСКОГО ГАЗА

The program module has been developed on the basis of package of applied MATLAB programs which allows to calculate speed of coating sedimentation over the section of plasma stream taking into account magnetic field influence of a stabilizing coil, and also to correct the obtained value of sedimentation speed depending on the value of negative accelerating potential, arch current, technological gas pressure. The program resolves visualization of calculation results.Разработан программный модуль на базе пакета прикладных программ MATLAB, который позволяет рассчитать скорость осаждения покрытий по сечению плазменного потока с учетом влияния магнитного поля стабилизирующей катушки, а также скорректировать полученную величину скорости осаждения в зависимости от значения отрицательного ускоряющего потенциала, тока дуги, давления технологического газа. Программа разрешает визуализацию результатов расчетов

ИССЛЕДОВАНИЕ ВЛИЯНИЯ СТРУКТУРЫ НА КОЭФФИЦИЕНТ ТРЕНИЯ МНОГОКОМПОНЕНТНЫХ ВАКУУМНО-ПЛАЗМЕННЫХ ПОКРЫТИЙ

It is revealed that under relatively low values of the accelerating potential Ubasic = 0-100 B) metal - silicon - nitrogen coating formation occurs when chemical reactions of nitride formation are absent An increase of the Ubasic value up to -(150-250) В leads to higher nitrogen concentration in the area of the crystallization, that changes thermodynamic conditions of coating grains’ growth and contributes to the nitrogen enriched stratum isolation in the form of streaks. Technological gas (nitrogen or argon) pressure increase promotes a roughness growth of the precipitated coating surfaces. It is determined that the best friction properties of the coatings have been obtained with friction along the hardened steel 40X. While using more ductile material as a rider (unhardened steel 45) the friction factor growth is observed. The instrumental coating ZrSiN precipitated with the Ubasic value -150B and having a layer structure is characterized by the least and most stable value of the friction factor (0.22 with friction along the unhardened steel 45 and 0.2 along the hardened steel 40X).Показано, что при относительно низких значениях ускоряющего потенциала (Uосн= = 0–100 В) формирование покрытий металл – кремний – азот происходит в условиях отсутствия химических реакций образования нитридов. Увеличение до Uосн = –(150–250) В ведет к росту концентрации азота на фронте кристаллизации, что изменяет термодинамические условия роста зерен покрытия и способствует выделению обогащенного азотом слоя в виде прослоек. Увеличение давления технологического газа (азота или аргона) способствует росту шероховатости поверхности осаждаемых покрытий. Установлено, что наилучшие фрикционные свойства покрытий получены при трении по закаленной стали 40Х. При использовании в качестве контртела более вязкого материала (из незакаленной стали 45) наблюдается рост коэффициента трения. Наименьшей и наиболее стабильной величиной коэффициента трения (0,22 при трении по незакаленной стали 45 и 0,2 – по закаленной стали 40Х) обладает инструментальное покрытие ZrSiN, осаждаемое при Uосн = –150 В и имеющее послойную структуру.

INVESTIGATIONS ON STRUCTURAL INFLUENCE ON FRICTION FACTOR OF MULTI-COMPONENT VACUUM- PLASMA COATING

It is revealed that under relatively low values of the accelerating potential Ubasic = 0-100 B) metal - silicon - nitrogen coating formation occurs when chemical reactions of nitride formation are absent An increase of the Ubasic value up to -(150-250) В leads to higher nitrogen concentration in the area of the crystallization, that changes thermodynamic conditions of coating grains’ growth and contributes to the nitrogen enriched stratum isolation in the form of streaks. Technological gas (nitrogen or argon) pressure increase promotes a roughness growth of the precipitated coating surfaces. It is determined that the best friction properties of the coatings have been obtained with friction along the hardened steel 40X. While using more ductile material as a rider (unhardened steel 45) the friction factor growth is observed. The instrumental coating ZrSiN precipitated with the Ubasic value -150B and having a layer structure is characterized by the least and most stable value of the friction factor (0.22 with friction along the unhardened steel 45 and 0.2 along the hardened steel 40X)

DEVELOPMENT OF PROGRAM MODULE FOR CALCULATING SPEED OF TITANIC PLASMA SEDIMENTATION IN ENVIRONMENT OF TECHNOLOGICAL GAS

The program module has been developed on the basis of package of applied MATLAB programs which allows to calculate speed of coating sedimentation over the section of plasma stream taking into account magnetic field influence of a stabilizing coil, and also to correct the obtained value of sedimentation speed depending on the value of negative accelerating potential, arch current, technological gas pressure. The program resolves visualization of calculation results