Uniform Distribution Of Components Research Articles

Study on mechanical alloying behavior and thermal stability of HfMoNbTaTi refractory high-entropy alloy

The present study prepared HfMoNbTaTi refractory high-entropy alloy powders with uniform distribution of components by mechanical alloying (MA). Six scenarios were designed to investigate the effects of rotational speed, milling duration, ball-to-powder weight ratio (BPR), and process control agent (PCA) on the alloy powder to achieve complete alloying, controlled morphology, and refined grain size. Results showed that the alloying efficiency and lattice strain increased significantly while the grain size decreased with increased rotational speed and BPR. In addition, the content of impurity elements (e.g., C, O, and Fe) also increased. Stearic acid added as PCA effectively prevented cold-welding and refined the particle/grain size but led to the appearance of unknown carbides. Excellent thermal stability was provided by the mechanically alloyed powders when annealed below 1000 °C. In contrast, the single body centered cubic (BCC) solid solution structure decomposed at 1200 °C annealing, and the decomposition temperature range was 942.5 °C–1041.2 °C based on the DSC curve. Finally, the dissolution pattern of components, the size mismatches effect, impact energy, and the optimal range of mechanical alloying process parameters were discussed in detail.

Formation of Bioresorbable Fe-Cu-Hydroxyapatite Composite by 3D Printing

Studies of the microstructure, phase composition and mechanical characteristics, namely the microhardness of metal–ceramic composites made of Fe 90 wt.%–Cu 10 wt.% powder and hydroxyapatite (Fe-Cu-HA), are presented in the manuscript. The composite material was obtained using additive manufacturing based on the 3D-printing method, with different content levels of powder (40, 45 and 50%) and polymer parts (60, 55 and 50%). It is shown that varying the proportion of Fe-Cu-HA powder does not significantly affect the elemental and phase compositions of the material. The X-ray phase analysis showed the presence of three phases in the material: alpha iron, copper and hydroxyapatite. It is shown in the experiment that an increase in the polymer component of the composite leads to an increase in the defectiveness of the structure, as well as an increase in microstresses. An increase in the mechanical properties of the composite (Vickers microhardness), along with a decrease in the percentage of Fe-Cu-HA powder from 50 to 40%, was established. At the same time, the composite containing 45% Fe-Cu-HA powder demonstrated the maximum increase in the microhardness of the composite by ~26% compared to the composite containing 50% Fe-Cu-HA powder, which is due to the more uniform distribution of components.

Modeling Of Polymer Melt Flow In The Annular Channel Of A Disk Extruder

Purpose. Polymer products are used in industry due to their performance properties. The homogeneity of the melt is essential for the quality of the final product. Uniform distribution of components and properties ensures homogeneity of the product's physical and mechanical characteristics. Insufficient homogeneity can lead to defects in the product. The homogenization zone plays an important role in ensuring a homogeneous melt. In a disc extruder, the homogenization zone consists of four consecutive channels. In order to describe the flow for the entire homogenization zone, it is necessary to model the first channel first. Therefore, the main purpose of this work is to model hydrodynamic and thermal processes during the flow of a non-Newtonian fluid in a straight annular channel in a non-isothermal regime, as well as to create a general procedure for further calculations for other channels. Methodology. The analysis of publications was carried out. The procedure for calculating the velocity and shear rate of the longitudinal and tangential melt flow, the effective melt viscosity, and the calculation of the melt temperature change along the length of the annular gap in an analytical form was developed. Findings. In accordance with the developed procedure, the values of tangential and longitudinal velocities and shear rates were calculated. The graphical dependences of the distribution of tangential and longitudinal velocities and shear velocities of the melt flow along the width of the annular channel, the distribution of pressure and the temperature of the polymer melt averaged over the width of the gap along the length of the annular channel are presented. Originality. In this work, a stationary flow in a straight annular channel was modeled for LDPE of the 15803-020 grade in a non-isothermal regime. A general procedure for further calculations for other channels of the homogenization zone has been developed. Practical value. The given calculation procedure can be applied to the following channels of the homogenization zone, which allows describing the melt flow for the entire homogenization zone.

Investigation of the possibility of controlling the formation of physical and mechanical properties of aluminum alloys under pressure crystallization

The study of scientific and technical materials showed that the existing control systems for technological processes of casting with crystallization under pressure are not effective enough. The paper presents a control system capable of real-time measurement, control and correction of the main technological parameters of the process, such as the time and nature of the temperature distribution in the tooling and casting, the rate of pressure imposition on the crystallizing metal, the magnitude of the applied pressure. These parameters have a direct impact on the formation of the properties of the final product. The paper defines the parameters of the response of the control system to fast crystallization processes for the timely prediction of the properties of the final product. The paper proposes a technology for metal processing by pressure prior to the onset of crystallization. In the process of conducting experimental studies in castings, it was possible to achieve the same uniform distribution of components, gas and non-metallic inclusions, as in a superheated liquid metal, bypassing the development of diffusion. As a result of ultrafast application of pressure to a level of 500 MPa on the liquid metal, it was possible to realize the process of compression of the crystal lattice to such limits at which it was possible to exclude the diffusion of components along structural defects. Due to the programmed application of pressure on the liquid and crystallizing one, the idea of controlling the processes of distribution of intermetallic compounds, non-metallic and gaseous inclusions has been realized.

Исследование структуры и свойств быстрозатвердевших оловянно-цинковых эвтектических сплавов, легированных сурьмой

The study results of the phase composition, microstructure, and mechanical properties of rapidly solidified foils of Sn—Zn eutectic alloys doped with antimony are presented. Alloy foils are characterized by uniform distribution of components. The rapidly solidified eutectic alloy consists of dispersed separations of the zinc phase, distributed in a tin matrix; antimony forms an intermetallic compound with zinc. The rapidly solidified eutectic alloy doped with antimony has a microcrystalline structure, no texture is observed. At small grain sizes, twins are formed in eutectic alloys with antimony. The microhardness of the foils increases with increasing antimony concentration. At room temperature, during storage of rapidly solidified foils, decomposition of the supersaturated solid solution is observed. Annealing the foils leads to a decrease in microhardness and coarsening of the microstructure.

MATHEMATICAL MODELLING OF THE PROCESS OF VIBRATION MIXING OF MINCED SAUSAGE

The relevance of the study is determined by the need to optimise the process of mixing minced meat in the production of sausages “Ozdorovchi” to reduce the duration of the technological operation, energy and raw material costs. Therefore, the article is concerned with the substantiation and determination of the amplitude-force parameters of a vibro-mechanical machine for mixing sausage mince ingredients. The leading method for studying this issue is mathematical modelling, which allows for comprehensive consideration of the patterns of changes in the main parameters of the oscillatory process. The article theoretically substantiates the expediency of using vibration impact to provide a rapid and uniform distribution of components in the minced mass. An experimental model of a vibrating machine for mixing minced sausage ingredients has been developed. The calculation scheme of the investigated technical system of the process of vibration mixing of minced sausages “Ozdorovchi” is compiled. The equation of motion of the executive bodies of the system is compiled. The dependences for the equations of motion of the actuators of the vibration mixer are determined. Dependences for the main characteristics of the oscillatory system under study are calculated. Based on the analysis of the graphical representation of the amplitude-force dependences, the working amplitude of oscillations of the mixing tank is substantiated in the range of 2-2.5 mm. It is established that the implementation of the required operating oscillatory mode requires for a given capacity relatively small power consumption in the range of 500-600 W. Optimal parameters for mixing minced meat with vibration intensification of the process, as well as the use of appropriate ingredients, allow for achieving a comprehensive technological effect while minimising energy consumption. Therefore, the materials of the article are of practical value for the meat processing industry in the technology of boiled sausage products with health-improving properties

Comparison the Preparation Methods of Powder Feedstock for Laser Powder Bed Fusion

Four various methods of powder feedstock preparation for laser powder bed fusion are compared. Application of commercial spherical powder leads to the formation of single-phased state. Powder mechanically alloyed during 14 minutes in air atmosphere provides conditions for the formation of double-phased state with nonuniform distribution of components in the samples. Mechanical alloying in Ar-atmosphere during 30 minutes leads to the formation of double-phased state with more uniform distribution of components and precipitations of Cr2O3. Preliminary mechanical sieving of the powder allows to produce double-phased samples with nonuniform distribution of components comparable with that in samples produced from powder mechanically alloyed during 14 minutes in air atmosphere. Microhardness of all the studied samples produced from all the studied powders was comparable. All the proposed methods of powder feedstock preparation are applicable in laser powder bed fusion depending on the required properties, elemental and phase composition of the final product.

Hydrogel Alginate Seed Coating as an Innovative Method for Delivering Nutrients at the Early Stages of Plant Growth.

Seed coating containing fertilizer nutrients and plant growth biostimulants is an innovative technique for precision agriculture. Nutrient delivery can also be conducted through multilayer seed coating. For this purpose, sodium alginate with NPK, which was selected in a preliminary selection study, crosslinked with divalent ions (Cu(II), Mn(II), Zn(II)) as a source of fertilizer micronutrients, was used to produce seed coating. The seeds were additionally coated with a solution containing amino acids derived from high-protein material. Amino acids can be obtained by alkaline hydrolysis of mealworm larvae (Gly 71.2 ± 0.6 mM, Glu 55.8 ± 1.3 mM, Pro 48.8 ± 1.5 mM, Ser 31.4 ± 1.5 mM). The formulations were applied in different doses per 100 g of seeds: 35 mL, 70 mL, 105 mL, and 140 mL. SEM-EDX surface analysis showed that 70 mL of formulation/100 g of seeds formed a continuity of coatings but did not result in a uniform distribution of components on the surface. Extraction tests proved simultaneous low leaching of nutrients into water (max. 10%), showing a slow release pattern. There occurred high bioavailability of fertilizer nutrients (even up to 100%). Pot tests on cucumbers (Cornichon de Paris) confirmed the new method’s effectiveness, yielding a 50% higher fresh sprout weight and four times greater root length than uncoated seeds. Seed coating with hydrogel has a high potential for commercial application, stimulating the early growth of plants and thus leading to higher crop yields.

Tailoring the BaCoO3-CeO2 catalyst for NO direct decomposition: Factors determining catalytic activity

The 5%BaCoO3-CeO2 catalysts show excellent catalytic performance for NO direct decomposition; however, the reasons for the high activity remain to be explored. Here, the catalyst was prepared by different methods (citric acid–nitrate one-pot method, impregnation method and mechanical mixing method), aiming to reveal the factors determining the catalytic activity. The results show that the one-pot derived materials display superior activity and oxygen resistance, which is stemmed from the smaller grains and uniform distribution of components, higher surface area, larger interface, better redox activity, faster oxygen desorption kinetics and better NO sorption capability. The catalytic mechanism was discussed based on the diffuse reflectance infrared Fourier transform spectroscopy and kinetic study. This work demonstrates that the one-pot method is promising to synthesize high performance heterogeneous catalysts and the derived 5%BaCoO3-CeO2 is a competitive candidate for NO direct decomposition.

Liqui-Tablet: the Innovative Oral Dosage Form Using the Newly Developed Liqui-Mass Technology

In this study, an attempt was made to produce Liqui-Tablets for the first time. This was carried out through the compaction of naproxen Liqui-Pellets. The incentive to convert the novel Liqui-Pellet into Liqui-Tablet was due to the array of inherent advantages of the popular and preferred tablet dosage form. The study showed that naproxen Liqui-Tablet could be successfully produced and the rapid drug release rate (100% drug release ~ 20 min) could be achieved under pH 1.2, where naproxen is insoluble. It was observed that the different pH of the dissolution medium affected the trend of drug release from formulations with varying amounts of liquid vehicle. The order of the fastest drug-releasing formulations was different depending on the pH used. The presence of Neusilin US2 showed considerable enhancement in the drug release rate as well as improving Liqui-Tablet robustness and hardness. Furthermore, images from X-ray micro-tomography displayed a uniform distribution of components in the Liqui-Tablet. The accelerated stability studies showed acceptable stability in terms of dissolution profile.

Chitosan succinate and food-grade chitosan for the creation of tissue-engineering structures by the laser method

Laser radiation makes it possible to form a composite material with laser radiation, which is intended for use as cellular- and tissue-engineering structures. It is important to obtain a uniform distribution of components throughout the volume of such material. Intermolecular interactions between chitosan and single-walled carbon nanotubes (SWCNTs) affect the structure of the composite. The results of IR spectroscopy and nonlinear optical studies have shown that the effect of laser radiation has different effects on the two types of chitosan, which was clearly demonstrated by SEM studies. Upon detailed examination, agglomerates in the composite material are clearly visible. Chitosan succinate less prevents the formation of agglomerates from SWCNTs, as a result of which a high agglomeration of nanotubes occurs among themselves in the composite material. The corresponding formations are distinguishable in the SEM images.

Graphene-alumina nanostructured hybrid: synthesis with use dodecylamine and physicochemical properties

Combination of sol–gel and sonochemical techniques is suggested for producing a nanostructured graphene–alumina hybrid, which is a promising raw material for manufacturing fine-grained ceramics. This study focuses on the use of dodecylamine both in the sol–gel synthesis of Al-containing particles and in sonochemical graphene exfoliation. It has been shown that, when forming graphene–alumina composite in a reaction mixture of Al-containing sol and graphene suspension, graphene sheets take part as a template in the formation of a hybrid structure. Graphene sheets orient sol particles on their surface due to van der Waals interaction and control growth and direction of oligomeric gel chains. The graphene sheets limit the growth of Al-containing particles, which leads to an increase in the specific surface of the hybrid as compared to an alumina powder sourced from the same sol. The proposed approach enables the preparation of chemically homogeneous composite nanopowders with uniform distribution of components.

Influence of design and technological parameters of a high-speed paddle mixer on the quality of dry building mixes

Today, one of the most promising building materials is dry building mixes. Their production is not only a large segment of the construction market, but also a kind of testing ground for promising developments of modern technological equipment. The paper discusses the design of a high-speed fixed drum paddle mixer for producing modified dry building mixes with a complex recipe. The question is raised about the complexity of the uniform distribution of components in the total volume of the mix. A number of existing factors affecting the distribution of components of the prepared mix are determined. Criteria for evaluating the quality of the finished mix are given. The method for determining the influence of design and technological parameters on the quality indicators of the finished product is described. The method of experimental research that allows evaluating the influence of the design and technological parameters of the mixer on the inhomogeneity coefficient of the resulting dry construction mix is presented. The obtained results confirm the effectiveness of the proposed design of a high speed paddle mixer to obtain high-quality modified dry building mixes at a minimum rate of heterogeneity of the mixture, as well as other indicators to measure the quality of the final product, diagrams of dependence of inhomogeneity coefficient of structural and technological parameters of the mixer are given. Rational values of the main design and technological parameters of the mixer for the production of dry building mixes are given.

Design, calculation and use of the multipurpose vacuum ground meat mixer

Ground meat mixers mixing minced muscle tissue with other pre-formulated ingredients, are among the most common types of specialized meat processing equipment. The quality of minced meat, this being a food dispersed medium, including a solid, liquid and, in part, a gas phase, is determined by the dispersity and uniformity of its structure, as well as the uniformity of the distribution of components, that is, by the efficiency of the mixing process. The research carried out made it possible to theoretically substantiate the processes of mixing minced meat with the help of specialized technological equipment, including that providing vacuuming of processed food masses. A list of regulatory requirements for the structures of industrial meat mixers, which determine their technological efficiency, safety and hygiene, is given. Two main layouts of the specified equipment are described, horizontal and vertical. The design of a horizontal compact vacuum meat mixer with a coaxial double working spiral is presented. The results of work on the creation of a model range of vertical vacuum meat mixers are described, the possibility of using vertical vacuum machines for maceration by massaging medium-sized and small-sized meat raw materials is proven. It is advisable to carry out such a transformation of the equipment by replacing the working bodies of mixing with special massaging arms, these ensuring the most efficient performance of the specified technological operation. The diagram is presented, the design is described and the working cycle of the vertical vacuum machine with the geometric capacity of the working bowl is 0.15 m is described; the main technological and dynamic calculations of the said machine are given. The calculations made it possible to create an advanced non-metal-intensive design of a vacuum machine for mixing minced meat and/or massaging meat raw materials, which meets current requirements for equipment of the purpose. Studies of the quality of mixing of ground meat have shown that vacuuming makes it possible to consistently achieve a better density of minced meat, and for minced meat processed on an atmospheric mixer, a more uniform distribution of components was characteristic.

Polymerization kinetics and control of the components of a mesophase pitch

It is important to increase the content of pyridine soluble in mesophase pitch to improve its spinnability. A naphthalene isotropic pitch was used as the raw material to prepare mesophase pitch by polymerization. The components of the polymerized products were analyzed by solvent extraction with benzene and pyridine, and classified as benzene soluble (BS), pyridine insoluble (PI) and benzene insoluble but pyridine soluble (BI-PS). The effects of polymerization temperature, time and the components of the raw material on the distribution of the components and optical texture of the mesophase pitch were investigated. The reaction kinetic constants were calculated assuming a consecutive reaction from BS to BI-PS, then to PI. Results show that a mesophase pitch with a relatively uniform distribution of components is obtained after reaction at 430 °C for 20 h from an isotropic pitch pre-polymerized at 400 °C for 10 h. The mesophase pitch synthesis reaction has a significant auto-acceleration effect in that the reaction rate constant of a heavy component is larger than a light one. The reaction rate becomes faster and faster as the molecular weight of the pitch increases in the latter stage of the synthesis reaction. Therefore, the initial component of raw pitch, reaction temperature and time have a decisive influence on the distribution of components in the mesophase pitch.

3D printed Er3+/Yb3+ co-doped phosphosilicate glass based on sol-gel technology

We demonstrate a method to manufacture Er3+/Yb3+ co-doped phosphosilicate glass by the digital light processing (DLP) 3D printing based on sol-gel technology. The sol-gel technology was used to fabricate the rare earth ions doped photocurable printing ink to achieve excellent fluidity, tunable composition and uniform component distribution. Following photopolymerization of 3D printing, the parts underwent ageing and sintering at 1050 °C, which is much lower than conventional high temperature melting method (~1700 °C). To the best of our knowledge, this is the first time that rare earth ion doped multicomponent glass has been fabricated by 3D printing based on sol-gel technology. This method combined with fiber drawing technology provides a novel way to fabricate the rare earth ions doped glass fiber.

COMPOSITION AND SURFACE MORPHOLOGY OF COMPOSITE ELECTROLYTIC COATINGS CO-W-ZRO2

possibility of electrosynthesis and control of the composition and surface morphology of the composite electrolytic coatings of cobalt with refractory metals by varying the pulse current density has been proved. Composites deposited on copper substrate from biligand citrate-pyrophosphate electrolytes at 4 A/dm2 are distinguished by a developed surface and a more uniform distribution of components on the surface, increased tungsten content, almost 5 times higher than coatings deposited at 10 A/dm2, and a half reduction in oxygen percentage (up to 5.5%). This is explained by the inhibition of the hydrogen gas evolution reaction and the participation of hydrogen ad-atoms in the chemical reduction of intermediate tungsten oxides to metal when polarization is interrupted. Coatings obtained using pulsed current can be considered as composites of the composition Co-W-ZrO2, in which the oxide phase is formed directly in the electrode process as an intermediate for the incomplete reduction of tungstates. The topography of the films is characterized by the presence of grains of elliptical and spherical shape with crystallite sizes of 80 – 180 nm. On the main surface there are protrusions (large grains) with a diameter of 1 – 3 microns. The fractal dimension of the surface is 2.77, which indicates the 3D crystal growth mechanism during coating formation. According to the surface roughness parameters Ra and Rq, coatings belong to the 9th roughness class. By phase composition, composites are predominantly amorphous materials, which include nanocrystalline cobalt and intermetallic compounds Co3W and Zr3Co. Due to the quantitative and phase composition, surface morphology and fractality, the microhardness and corrosion resistance of Co-W-ZrO2 systems deposited at a current density of 4 А/dm2 are 20% higher than the coatings obtained at 10 A/dm2, and 3 times higher than the corresponding characteristics of the substrate.

ОБҐРУНТУВАННЯ НОНМІКСИНГОВОГО СПОСОБУ ФОРМУВАННЯ СУМІШІ ІЗ СИПКИХ МАТЕРІАЛІВ

Змішування є основною технологічною операцією під час виробництва преміксів для тварин. У сумішах, з яких виготовляють премікси, важливо забезпечити рівномірний розподіл компонентів, оскільки від цього залежать ефективність використання преміксів та їх безпечність. Суміші преміксів містять окремі компоненти в мікродозах, відповідно співвідношення між компонентами суміші може становити 1:10 та більше. Забезпечити високу якість такої суміші шляхом змішування компонентів неможливо. Рівномірний розподіл компонентів за об’ємом такої суміші можуть забезпечити нонміксингові способи формування сумішей. У статті обґрунтовано спосіб нонміксингового отримання суміші, що передбачає її формування з елементарних об’ємів суміші, в яких забезпечено необхідне співвідношення між компонентами. Цей спосіб дозволяє формувати суміш із компонентів із різними фізико-механічними властивостями та геометричними параметрами. У результаті теоретичних досліджень отримана залежність, яка дозволяє обґрунтувати елементарний об’єм суміші для реалізації запропонованого способу формування суміші. У разі формування технічними засобами елементарних об’єм суміші такої величини, можна отримати суміш високої якості, оскільки розподіл компонентів у ній буде наближатися до ідеального. Крім того, отримані залежності, які дозволяють розрахувати масу мікродоз компонентів для формування елементарного об’єму суміші та, відповідно, обґрунтувати режим роботи дозаторів.

The effect of surface morphology of Co-W-ZrO2 electrolytic composite coatings on the functional properties of alloys

The possibility of electrosynthesis and control of the composition and surface morphology of the composite electrolytic coatings (CEC) of cobalt with refractory metals by varying the pulse current density has been proved. Composites deposited on copper substrate from biligand citrate-pyrophosphate electrolytes at 4 A/dm2 are distinguished by a developed surface and a more uniform distribution of components on the surface, increased tungsten content, almost 5 times higher than coatings deposited at 10 A/dm2, and a half reduction in oxygen percentage (up to 5.5%). This is explained by the inhibition of the hydrogen gas evolution reaction and the participation of hydrogen ad-atoms in the chemical reduction of intermediate tungsten oxides to metal when polarization is interrupted. Coatings obtained using pulsed current can be considered as composites of the composition Co-W-ZrO2, in which the oxide phase is formed directly in the electrode process as an intermediate for the incomplete reduction of tungstates. The topography of the films is characterized by the presence of grains of elliptical and spherical shape with crystallite sizes of 80 – 180 nm. On the main surface there are protrusions (large grains) with a diameter of 1–3 microns. The fractal dimension of the surface is 2.77, which indicates the 3D crystal growth mechanism during coating formation. According to the surface roughness parameters Ra and Rq, coatings belong to the 9th roughness class. Due to the quantitative composition, surface morphology and fractality, the microhardness and corrosion resistance of Co-W-ZrO2 systems deposited at a current density of 4 А/dm2 are 20% higher than the coatings obtained at 10 A/dm2, and 3 times higher than the corresponding characteristics of the substrate. It was shown the catalytic activity of tungsten containing CEC in ethanol oxidizing reaction and corrosion resistance in media of different acidity.

Modeling of structure formation of energy-saturated heterogeneous composite material

One of the approaches to modeling of the structure formation of an energy-saturated heterogeneous composite material (EHCM) by mixing its components represented by liquid and solid phases was considered. To develop a model of the mixing process, one of the heuristic algorithms was used, i.e. the metal annealing method. The model is formalized with the condition of averaging the particle sizes within each of the fractions, as well as the morphology of their surface. As a representative element of the model, an elementary cell is adopted in the form of hexogonally densely packed particles around one introduced into the composition of the composite material (in small amounts, from 5 to 15 %) as a modifier. The voids in the cell are filled with liquid polymer. The developed model is based on the objective function, which assumes obtaining a uniform distribution of components with the required density of their packing and filling the voids with a liquid phase while minimizing the number of mixing iterations. A comparison of the values resulted during modeling with the measured characteristics of mixing on a particular mixer will make it possible to form a matching scale of the modeling results to the operating modes of technological equipment. This will determine the appropriate modes of mixing the components at the stage of development of the technological process of EHCM production.