КОНТАКТНЫЙ ЛОКАЛЬНЫЙ НАГРЕВ АЛЮМИНИЕВОЙ ОСНОВЫ С НАНОПОРИСТЫМ ОКСИДОМ АЛЮМИНИЯ ЛИНЕЙНЫМ ИСТОЧНИКОМ ТЕПЛА ДЛЯ ИСПОЛЬЗОВАНИЯ В ТЕРМОМЕТРИИ

The paper presents the results of thermal studies for a sample of aluminum with nanoporous alumina using thermal imaging measurements. As a heating element, a carbon thread based on a viscose technical thread was used. On the base of results, it was established that local heating of the sample surface by the contact method using a linear heat source can be used in thermometry to determine the thermal conductivity of solid multicomponent dielectric materials.В работе представлены результаты тепловых исследований для образца из алюминия с нанопористым оксидом алюминия, выполненных с использованием тепловизионных измерений. В качестве элемента нагрева применялась углеродная нить на основе вискозной технической нити. На основе результатов исследований показано, что локальный нагрев поверхности образца контактным способом с использованием линейного источника тепла может быть использован в термометрии для оценки теплопроводности твердых многокомпонентных диэлектрических материалов.

Сontact local heating of an aluminum base with nanoporous alumina by a linear heat source for use in thermometry

В работе представлены результаты тепловых исследований для образца из алюминия с нанопористым оксидом алюминия, выполненных с использованием тепловизионных измерений. В качестве элемента нагрева применялась углеродная нить на основе вискозной технической нити. На основе результатов исследований показано, что локальный нагрев поверхности образца контактным способом с использованием линейного источника тепла может быть использован в термометрии для оценки теплопроводности твердых многокомпонентных диэлектрических материалов. The paper presents the results of thermal studies for a sample of aluminum with nanoporous alumina using thermal imaging measurements. As a heating element, a carbon thread based on a viscose technical thread was used. On the base of results, it was established that local heating of the sample surface by the contact method using a linear heat source can be used in thermometry to determine the thermal conductivity of solid multicomponent dielectric materials

Features of the porous morphology of anodic alumina films at the initial stage of disordered growth

A characteristic feature of disordered porous anodic film growth at the initial stage of aluminum anodizing was revealed by varying the electrolyte type and anodizing voltage. The samples were obtained by the electrochemical oxidation of thin aluminum films (100 nm thick) on SiO2/Si substrates in a 0.3 M oxalic acid at 10–50 V and were studied by SEM. The ImageJ analysis of the images revealed the simultaneous development of two large groups of pores: major pores with a large diameter and minor pores with a smaller diameter. When anodizing in oxalic acid at 10–50 V, it has been shown that the ratio of the diameters of the major and minor pores remains constant and is about 1.17. Using a geometric model, we demonstrated that the centers of the minor pores are located inside the elementary hexagonal cell formed by the centers of the major pores. Moreover, our results are very close to the theoretical value of 2/√3. At the initial stage of disordered pore growth, the development of minor pores rather than major pores is not a random process and is determined by energy-efficient conditions for the development of pores inside the hexagonal cells formed by the major pores. The increase in compressive mechanical stress in the anodic film leads to an interruption in the development of such pores

Applying Aniline for P-doping of PEDOT:PSS Films to Improve Their Conductivity and Efficiency of Perovskite Solar Cells

Poly(3,4- ethylenedioxythiophene):polystyrene sulfonate (PEDOT: PSS) is responsible for hole extraction efficiency and hole transport in the perovskite solar cell structure. The inclusion of PSS reduces the conductivity of the PEDOT films, which inhibits hole transport and results in a low photo current of the perovskite solar cell. In this work, an aniline solution was used as an additive in the PEDOT: PSS thin film to increase electrical conductivity. Two different methods were used to incorporate the additive: surface and volume treatment. The results show that the surface treatment with aniline solution can significantly increase the conductivity of PEDOT: PSS film. Moreover, the photoconversion efficiency of the perovskite solar cell with such a PEDOT: PSS layer is increased 1.5 times compared to the untreated one

Recognitionand Analysis of Microstructure Parameters of Porous Anodic Films Using ImageJ

The most important parameters that characterize the microstructure of the films and determine the possibility of their use as porous templates are the pore diameter, porosity, and ordering of the porous structure. Therefore, to increase the efficiency of the use of porous anodic alumina films, it is important to investigate the effect of the formation modes on the microstructure. The aim of this work was to choose and optimize a model for processing experimental data obtained by scanning electron microscopy in the ImageJ to determine the parameters of the microstructure of porous films. The work shows the result of SEMimage analysis and obtains plots of pore diameter distribution by size and determines the diameter of the main pores

Investigation of the features of the porous morphology of anodic alumina films at the initial stage of anodization

The work is devoted to the study of the porous structure formation of anodic alumina films at the initial stage of aluminium anodizing. SEM images of the surface morphology of the oxalic acid anodic films were analyzed. It was shown that at the initial stage, both major and minor pores are formed, the diameter ratio of which is about 1.16 and does not depend on the anodizing voltage. The results obtained indicate that the minor pores in the anodic films are located inside hexagonal cells composed of the major pores

Исследование распространения теплового потока в теплопроводящих оксидных подложках с различной теплопроводностью методом линейного источника тепла

Introduction. For controlled thermal management of power electronics devices, an important task is to increase the efficiency of heat removal from active components. Aim. To introduce a new approach to placing a linear contact-type heat source on the surface of thin samples in order to study the features of propagation of heat fluxes in oxide substrates from materials with different thermal conductivities. Methods and materials. The paper presents the results of studies of the propagation of heat fluxes in oxide substrates with different thermal conductivity (glassceramic and aluminum oxide ceramic - polycor). To generate the heat flux, a linear heat source was used, for which an electrically conductive carbon fiber was applied. Results. Thermograms and temperature distribution profiles were obtained at different periods of heating time on the surface of the substrate with a heating element and on its reverse side. It was shown that the placement of the linear heat source, implemented using an electrically conductive carbon filament, on the surface of the studied samples and time monitoring of thermograms from two opposite surfaces of the samples allowed to obtain data for evaluating the thermal properties of oxide substrates. The distribution of the heat flux in a homogeneous material near the generation point had the form of a cone of a heat pipe with a base on the surface with a heat source. The thermal cone for an aluminum oxide ceramic substrate had a larger angle of inclination than that in the case of glassceramic. Conclusion. The results obtained allowed to propose a method for reduction of thermal resistance of a heatconducting substrate by creating conditions for increasing the area of heat-conducting section.Введение. Для контролируемого управления тепловыми процессами устройств силовой электроники важной задачей является повышение эффективности отвода тепла от активных компонентов. Цель работы. Представление нового подхода к размещению линейного источника тепла контактного типа на поверхности тонких образцов с целью исследования особенностей распространения тепловых потоков в оксидных подложках из материалов с различной теплопроводностью. Методы. Представлены результаты исследований особенностей распространения тепловых потоков в оксидных подложках с различной теплопроводностью (ситалл и поликор). Для генерации теплового потока использовался линейный источник тепла, в качестве которого применялась электропроводящая углеродная нить. Результаты. Получены термограммы и профили распределения температуры в различные промежутки времени нагрева на поверхности подложки с элементом нагрева и на ее обратной стороне. Показано, что размещение линейного источника тепла на основе электропроводящей углеродной нити на поверхности исследуемых образцов и мониторинг во времени термограмм с двух противоположных поверхностей позволяют получить данные для оценки эффективности тепловых свойств оксидных подложек. Распространение теплового потока в однородном материале вблизи места генерации имеет вид конуса тепловой трубы с основанием на поверхности с источником тепла. Тепловой конус для керамики имеет больший угол наклона, чем в случае ситалла. Заключение. Полученные результаты позволили предложить способ снижения теплового сопротивления теплопроводящей подложки за счет создания условий для увеличения площади теплопроводящего сечения

Morphology investigation of nanoporous anodic alumina films with image analysis

Aluminum films approximately 100 nm thick were deposited on silicon substrates (SiO2 / Si) by thermal evaporation in a vacuum. Porous anodic alumina films were obtained in a potentiostatic mode at 20 V in 0.3 M aqueous solution of oxalic acid and 1.8 M aqueous solution of sulfuric acid. The main pore diameter was determined using the ImageJ software from SEM images. An algorithm determining the pore diameter in porous anodic alumina films was developed. In the nanoporous alumina films formed in sulfuric acid at 20 V the average pore diameter was 12.3 ± 0.1 nm. In the case of the oxalic acid electrolyte, the nanoporous alumina films formed at 20 V had an average pore diameter of 14.8 ± 0.1 nm. The obtained results are in a good agreement with the literature

Thermal and electrical characteristics of flat heaters made of aluminum with nanoporous anodic aluminum oxide and a resistive element of carbon filament

The results of studies of the thermal characteristics of aluminum heaters with a layer of anodic aluminum oxide are presented. In the design of an aluminum heater, a carbon electrically conductive filament based on a viscose technical fiber was used as a heating element. To seal the heater design, a silicone compound was used

Influence of Electrolyte Temperature on the Formation of the Morphology of the Porous Structure of Anodic Aluminum Oxide

The results of research on anodizing thin aluminum films 100 nm thick on SiO2–Si plates at 30 V in a 0.3 M aqueous solution of oxalic acid are presented. The effect of the electrolyte temperature on the morphology of porous anodic aluminum oxide (PAAO) films is studied. The pore diameter and interpore distance are determined by the computer analysis of the SEM images of the morphology of the anode films using the ImageJ software. The data obtained show that the pore diameter does not depend on the temperature of the electrolyte and the time of the process, but is determined only by the anodizing voltage. In the electrolyte temperature range of 5 to 40°C, the pore diameter of the PAAO films is 20 ± 0.5 nm, and the interpore distance is 77.7 nm. The research results indicate that a change in the temperature of the electrolyte, in contrast to the anodizing voltage, affects only the growth rate of the anode film, and not its porous morphology