Експериментально досліджено корозійну стійкість покриттів, отриманих плазмовим напилюванням порошку оксиду алюмінію плакованого двошаровими оболонками з титану, алюмінію або міді на сталеву та магнієву основу. Проведена термодинамічна оцінка взаємодії оксиду алюмінію з металевими оболонками при плакуванні. Встановлено вплив плакованих порошків на мікроструктуру та пористість плазмових покриттів і зміну поляризаційного опору під час випробувань в рідких агресивних середовищах.
Corrosion resistance coatings deposited by plasma spraying of alumina powders with clad metal PVD film were studied. Thermodynamical evaluation of the interaction of alumina with titanium and copper in cladding was produced. Possibility of interaction was evaluated assuming that the alumina dissolved in the titanium. The result was defined atomic percentage of oxygen and aluminum in the titanium at temperature of cladding. The influence of clad powders on the microstructure, porosity and polarization resistance of plasma-sprayed coatings during testing in corrosive environments was studied. The corrosion behavior of coating was studied by technique of a polarization change based on the measurement of the current between the two electrodes from the same metal and a coating when applied the polarization less than 20 mV.
Alumina powder for plasma spraying coated dual layer of titanium, aluminum or copper reduces the total porosity and improves in a 2–3 times the corrosion resistance of coated steel in 10 % solution H2SO4, HNO3 as well as more than an order of corrosion resistance of magnesium alloy in a 3 % NaCl solution.
Largest values at spraying on steel substrate of the polarization resistance in acid solutions respond coatings from alumina powder with dual layer clad PVD film of titanium and copper. This increase in the corrosion resistance depends more on the thickness of the top sprayed coating than to the material and thickness of sprayed underlayer. It is associated with a decrease in the amount connected pores. Largest values at spraying on the magnesium alloy of the polarization resistance in 3 % NaCl solution had coating on base of clad alumina powder with underlayer and the additional activation of the substrate surface by electrospark doping for improving adhesion strength.
Further research perspectives are to enhance materials for clad powders and more detailed studying of the corrosion damage mechanism at elevated temperatures of plasma-sprayed coatings from clad powders.
Наведено результати експериментальних досліджень двостадійного термоусідання поліпропіленової термоусадної плівки. Визначено залежності коефіцієнта усідання поліпропіленової плівки в поперечному та поздовжньому напрямках від температури. Порівняно одно- і двостадійне термоусідання.
Shrinkage called polymer films capable to contract under the influence of a temperature exceeding the softening temperature of the polymer. Different polymers have different properties at shrink, among which the most important is the shrink degree (shrink coefficient) and shrink stress. Shrink coefficient determines the multiplicity of reducing the linear dimensions shrink film, so that it gets the ability to tightly encircle the products subject to packaging, reproducing its outer contours.
The process of packaging products in shrink film consists of two phases: formation package by sealing it in shrink film; shrinkage of the film through its blowing hot air. Hot air is blowing of package realizing by heat chamber or by heat tunnel.
The aim of the paper is to investigate the shrink coefficient polypropylene film in the transverse and longitudinal directions, depending on the process temperature.
During the implementation of the shrink method in case the object is subjected packing, sharp transitions or sharp edges possible undesirable deformation and/or damage to the object itself, or injury (up to fracture) packaging film (that is destroying the integrity of the package), it would be appropriate to use a two-step incremental shrinkage. Stepwise shrinkage was carried out in two stages: the first stage of the film was in the heat chamber 2 s, and at the next shrink stage – 5 s. In carrying out the experiment was seen addiction at the time that the first shrink stage exceeding 2 s, the relaxation of the film makes it almost fully realized and further shrinkage is negligible. After finishing shrinkage processes coefficient determined after the first stage and the overall shrink and total in the transverse and longitudinal directions, depending investigated transverse and longitudinal coefficients shrink temperature.
A comparison of the experimentally obtained graph of the one-step and two-step in shrink follows that when shrink film at one stage, shrink ratio is increasing with increasing operating temperature, whereas the two-stage shrink biggest factor shrink was obtained at a temperature 170oC . The total shrink degree in two-stage process is almost the same as in the one-step shrink.
Розглянуто задачу статичної оптимізації зневоднення та гранулювання мінеральних добрив у псевдозрідженому шарі за квадратичним критерієм якості. Одержано оптимальні значення витрат вихідного розчину й теплоносія – повітря.
Commercial operation of pellet fluidized bed shows that the reliable operation of such a technological system affects a large number of factors. Their impact on the stability of a technological system for the production of fertilizers with desired properties is still not investigated in full. Despite the fact that some production work for over 25 years, the optimal regime of granulation and drying processes to be found.
The aim of the paper is to investigate the process of obtaining continuous granulated product of a given dispersion composition. The results of static optimization of the process of dehydration and granulation with water solutions of ammonium sulfate using fluid bed granulator are considered.
There are many approaches to the optimization problem. Given the nature of the process optimization is feasible by changing the air flow and discharge of the product from the apparatus to maintain a given pressure drop in the reservoir. Chance of a different formulation of the optimization problem is show. It is proposed to consider air flow control actions and the cost of the initial solution.
In the analysis of processes involving phase transition, in terms of optimization, a material effect on the kinetics of the process with energy performance. Minimizing temperature deviation layer and spending power to carry out the process, was chosen as a quadratic criterion.
The application of static optimization by quadratic quality criterion to determine the effect of temperature on energy efficient process parameters is considered. To ensure the sustainability of the load for a working solution must adequately increase the temperature of the coolant at the inlet to the machine. Increasing the mass flow of liquid agent – coolant spending limit at which the rate of coolant in the machine is equal to the minimum rate of removal of particles.
Solution of the problem connected static optimization by quadratic quality criterion. Temperature dependence of the layer of control actions showed the presence of pronounced local minima. Optimum values of the original cost of the solution and coolant – air.
Проаналізовано практичне застосування розроблених енергоефективних технологічних засад одержання препрегів для базових процесів їх одержання, а саме змішування, просочування волокнистих наповнювачів та дозованого нанесення на них епоксидних зв’язуючих, із використанням ультразвуку.
It was stated that the basic processes of impregnation and dosed application are the important parts of the production of prepreg for polymer composite materials (PCM). This is because the quality of the impregnation is influenced by such factors as the presence or absence of air inclusions (so-called "bottle effect") in the structure of the impregnated fibrous filler during its impregnation, the homogeneity and the viscosity of the polymeric binder, good surface wettability of fibrous filler and so on.
The essence of the developed energy-efficient technological foundations is based on the integrated use of ultrasonic for the basic processes of manufacture of prepregs to overcome the above said drawbacks in their preparation.
Studies have shown that the effective effect of ultrasonichelps to improve the homogenization of the polymer binder, activation of fiberfill surface to improve its wettability with the polymer binder drainage structures fiberfill right before impregnation and to increase the productivity of the process of impregnation and dosed application of polymer binder by increasing the speed of a fiber-fill drawing with improving of properties of the final solidified PCM.
Furthermore, it was found out that the use of ultrasonic exposure to the impregnated fibrous filler in the bath and also to already impregnated fibrous filler may be regarded as an effective method for automatically maintaining of the required amount of containing of the binder polymer in the impregnated fibrous filler.
In addition, due to the action of ultrasonic reduces cumulative time of receipt of the prepregs, which ultimately also contributes to energy saving in the preparation of prepregs.
The result of the application of the developed technological bases and the equipment is the increase of productivity of the impregnation processes and dosed application of polymer binder, i.e. speed of drawing of the material and speed of removal of excess polymer binder in the preparation of a homogeneous impregnated material with virtually no air pockets.
This allows recommending the developed new technological basis of three-stage ultrasonic processing and the necessary equipment as a reliable means to maintain a predetermined value of the quantity (stabilization) of content of the polymer binder impregnated fabric filler.
A number of case studies (including the use of impregnation-drying machine MPT-3M) with the developed technological bases and equipment, providing energy saving process of preparing a polymer binder, impregnating a fibrous filler and dosed application to them the polymer matrix using ultrasonic was studied.
It is noted that with the use of the developed technological bases and equipment is achieved the use of highly viscous and highconcentrated impregnating compositions, and compositions with the disperse filler.
Проведено експериментальне дослідження середньої товщини плівки, гальмівного впливу стінки на рідину в роторно-плівковому апараті з висхідним потоком.
Intensification of heat and mass transfer processes in liquids most simply solved by using thin-film equipment. Organization processes in thin layers of liquid widely used in chemical, biotechnology, food and other industries. The basic requirement for improving the quality of thermally labile substances is to ensure continuity of the film and a small residence time of the product on the heating surface. In rotary apparatus with falling film problem is to ensure continuity of the film, especially in the case of high intensity of evaporation. Organization upward flow in rotor-film devices allows you to create favorable conditions for the processing of thermally labile compounds.
Due to the complexity of studying hydrodynamics upward flow in a rotor-tape machine can not only describe the process of theoretical functional dependencies. Experimental studies provide an opportunity to present their results in the form of empirical equations that reflect the real picture of the process.
One of the main parameters characterizing the hydrodynamics of rising film flow is pumping and the average thickness of the film. The results of experimental studies for the height dependence of the number of revolutions of the rotor and the volume of fluid in the apparatus are based on the inhibitory influence of the wall. Also, the average film thickness is depending on the number of revolutions of the rotor and the fluid flow.
The study was carried out on a glass model of rotary-film device with a transparent wall , the height of discharge (235 mm) rotor with rigid blades, adjustable blade number (2 to 6) and the gap between the blades and the wall (0.75…2.00 mm). Experiments were carried out during isothermal upward flow of water at a temperature of 18 °C. Number of blades was 6, the distance between the blade and the wall – 2 mm. Rotor speed was changed from 30 to 100 rad/s.
It was established that the ratio of inhibitory effect increases with the amount of fluid that is in the machine, and decreases with increasing angular velocity. The thickness of the film increased with the flow and decreases with increasing angular velocity. The results are summarized relevant equations. Calculated values differ from the experimental values of less than 5 %. Reliability approximations made 0.96, indicating a sufficient reproducibility.
The results can be used for design calculations and further research rotary-film devices with a rising film.
Повідомляються результати досліджень із встановлення оптимальних технологічних параметрів спікання інструментальних композитів з надтвердих матеріалів із мінімально можливою щільністю потужності і максимально можливими швидкостями руху лазерного випромінювання відносно дослідного зразка.
Optimal technological parameters of laser sintering with the aim to minimize laser beam power density and to maximize travel speed of laser beam or workpiece for the formation of cutting tools from super-hard composites were determined in this paper.
Використовуючи експериментальні дані про електропровідність сипкого коксу та графітованих сумішей, одержано залежності, що дозволяють визначати питомий електричний опір залежно від вмісту сирого й графітованого коксу в суміші в діапазоні температур від 20 до 1000 °С, а також питомого електричного опору для сирого коксу й графітованої суміші залежно від її гранулометричного складу.
Using previously obtained experimental data on the electrical conductivity of bulk (carbon) coke and graphite mixtures obtained relationships to determine the value of specific electric resistance depending on the composition of crude coke and graphite in a mixture in the temperature range from 20 to 1000 °C. Also dependence of the electric support for raw coke and graphite convertible mixture depending on its grain size is obtained.
Study of the electrical resistivity of carbon materials relates to the field of saving energy in the furnaces of graphitization. Carbon materials are not only the raw materials for electrode manufacturing and coal products, but also are the active electrical resistivity in the furnaces of graphitization and can be recovery and thermal insulation. Resistance value allows drawing conclusions on the structural transformations that took place in the carbon material, caused by external influences on him. Electrical resistivity of the coal charge exhibits a significant influence on the uniformity of distribution of electric power in the volume of the furnace and has a direct impact on product quality and losses of energy.
Literature data of electrical resistivity of the coal charge can’t be used without additional analysis and calculations in different technological process conditions. The reason for this is the dependence of properties coal charge not only on the temperature range, but also on the particle size distribution of the starting materials and the degree of graphitization.
The article draws previously obtained experimental data on the electrical conductivity of particulate coke and graphite mixtures. Analysis of the experimental data showed that for the materials in question observed correlation of electrical resistivity particulate carbon materials on the particle size and the degree of graphitization.
The results of our study allow defining the magnitude of the electrical resistance depending on the composition of the mixture of raw coke and graphitized, the particle size of the starting components of the mixture at temperatures ranging from 20 to 1000 ºC.
The obtained dependences are necessary to find the optimal properties of the coal charge used in the production, as well as for the development of energy-saving regulations in technological processes of the enterprises.
Наведено результати досліджень впливу температурного поля скловарної печі на показники якості скловиробів. Одержані кореляційні функції, котрі показують зв'язок між характерними температурними точками у печі, в котрих розташовані термопари, та основними показниками якості скловиробів. На основі даних кореляційних функцій визначено точку вимірювання температури котра є визначальною для основних показників якості.
Results of studying the temperature field effect on glass products quality factors are provided. Correlation functions that show relationship between furnace’s characteristic temperature spots with thermocouples installed and the main quality factors of glass products are received. Temperature measurement spot which defines the quality factors of glass products is found based on the correlation functions.