Containerless Methods Research Articles

EFFECTS OF REFRACTIVE INDEX AND ASPECT RATIO ON THE PARTICLE IMAGES IN A LEVITATED DROPLET

A technique using droplets suspended by ultrasound has attracted attention as one of the containerless processing methods. While this can avoid contamination from the container, it is known that ultrasonic levitation creates flow fields inside and outside the droplet. For more precise droplet control, it is desirable to elucidate the internal flow of the droplet, and measurements of the internal flow have been performed using the particle image velocimetry (PIV). The aim of this study is to elucidate the internal flow field behavior by solving optical problems and improving the accuracy of velocity field measurements in levitated droplets. The fluid that is to be investigated is scattered with small tracer particles and illuminated by a laser to capture the flow on a created laser sheet. The curvature distortion is successfully visualized using the PIV approach toward distortion correction using calibration methods. The curvature distortion illustration was performed based on the refractive index and aspect ratio of the simulated droplet in acrylic materials. The fluid flow, affected by droplet curvature and refractive index, has been visualized for both levitated and simulated droplets. The experimental results showed that the droplet curvature can be distorted in two types such as radial and tangential distortions and increase as the refractive index and aspect ratio increases.

(Invited) The Electrostatic Levitation Furnace Onboard the International Space Station for Container-Less Material Processing and Thermophysical Property Measurements at Extremely High Temperature

Electrostatic levitation is one of the container-less processing methods which utilizes Coulomb force between a charged sample and surrounding electrodes. Contrary to the other methods, electrostatic levitation cannot create a potential minimum, so high-speed feedback position control is necessary. Because of this technical difficulty, development of this method was behind to other methods, such as electromagnetic levitation, or acoustic levitation. Samples can be levitated even in ground. However, to levitate samples against gravity, huge electric field and huge surface charge on the sample are required. This creates some limitations in ground experiments. Firstly, Oxides samples are hard to levitate due to low surface charge. Secondly, experiment in inert gas environment is impossible to prevent electric discharge among electrodes. These limitations can be easily solved in microgravity. Oxides sample cane be levitated and melted. Metals and alloys can be processed in inert gas to suppress evaporation.The electrostatic levitation furnace on the International Space Station (ISS-ELF) developed by Japan Aerospace Exploration Agency, was launched to the ISS in 2015. Then, Installation to the MSPR (multi-purpose Small Payload Rack) was conducted in the next year. Since then, a variety of oxide/ metal samples have been levitated and melted in the facility. The ISS-ELF has a capability to measure thermophysical property of extremely high temperature melts. Density, Surface tension, and viscosity can be measured by this facility. Status of thermophysical property measurements is described in this presentation.

Thermophysical Property Measurements of Refractory Oxide Melts With an Electrostatic Levitation Furnace in the International Space Station

Due to their high melting temperatures and the risk of contamination from the crucibles, molten oxides which melting temperatures are above 2000 °C can hardly be processed using conventional methods. This explains that their thermophysical properties are very scarce. Containerless methods with gas flows have been developed and several thermophysical properties such as density, surface tension, and viscosity have been reported. However, the gas flow has detrimental side effects such as deformation of the sample and induction of internal flows in the molten sample, which affect the accuracy of the measurements. The electrostatic levitation furnace onboard the International Space Station (ISS-ELF), which utilizes the Coulomb force to levitate and melt samples in microgravity, has several advantages for thermophysical property measurements of refractory oxide melts. Levitation without a gas flow coupled to a reduced gravity environment minimizes the required levitation (positioning) force and reduces the deformation as well as the internal flow. This report briefly introduces the ISS-ELF facility and the thermophysical property measurement methods. The measured density, surface tension, and viscosity of molten Al2O3 are then presented and compared with the ones obtained by other methods. Finally, the measured data of refractory oxides whose melting temperatures are above 2,400 °C are summarized.

ЕКОЛОГІЧНА ОЦІНКА СТАНУ ПОВОДЖЕННЯ З ТВЕРДИМИ ПОБУТОВИМИ ВІДХОДАМИ В МІСТІ УМАНЬ

The study of municipal solid waste management was carried out on the example of the city of Uman, the features of the municipal waste collection were considered. One of the promising utilization methods of the municipal waste organic component is proposed — anaerobic fermentation with subsequent composting of the resulting products. Urban population growth, industrialization, urbanization and economic prosperity lead to an increase in municipal solid waste (MSW). The aim of the work was to consider the characteristics of municipal solid waste management using the example of the city of Uman; inspect the features of collecting municipal waste; consider a separate collection system; identify problems and possible solutions. According to the statistics of Uman city council, 73-75 tons of municipal waste per day are delivered to the landfill. The control is carried out on the composition of the waste entering the landfill. Sorting takes place using a sorting line, which was put into operation in October 2016. Removal of municipal solid waste from the residential sector is carried out according to the schedule. The waste from the private sector of the city is removed during the day. Transportation (transport) of municipal waste is carried out by specially equipped vehicles. On the plots of the private residential sector, the collection of municipal waste is carried out by containerless and container methods. The containerless method is used in those areas of private building, where the possibility of the garbage truck's driving and its maneuvering are limited. Analysis of the current state of municipal solid waste management in the city of Uman showed that the main reasons for the increase in the volume of environmental pollution due to municipal solid waste is the lack of a high-quality management system in the field of MSW management, and especially the outdated waste collection and transportation scheme. The state of MSW management does not meet modern requirements. At the landfill, as a result of the introduction of the technology for the production of biogas from municipal solid waste, it is possible to obtain marketable products — biogas and compost. The city can receive income from the use of biogas as an alternative source of energy for heating buildings or from its consuming by the population. For the city of Uman, the volume of biogas formation at the MSW landfill in 2018 would have amounted to 5,441,280 m3, and in 2019 – 5,424,930 m3.Thus, it is possible to obtain significant volumes of biogas for the production of both heat and electricity. As a result of the study, recommendations were developed to improve the system for collecting municipal waste in the city of Uman. One of the promising utilization methods of the municipal waste organic component in the city of Uman is anaerobic fermentation followed by composting of the resulting products.

Thermophysical Properties of an Fe57.75Ni19.25Mo10C5B8 Glass‐Forming Alloy Measured in Microgravity

Iron‐based metallic glasses are among the lowest‐cost form of amorphous metals and have numerous potential applications, such as wear‐resistant coatings, cutting tools, and gears. There is an increased interest for using this novel alloys as protective coatings and to produce structural elements by additive manufacturing. If an accelerated process development is desired, computer‐based process simulations are nowadays a vital tool. As a consequence, high‐quality measurements of the thermophysical properties in the solid and liquid phases are essential for developing numerical simulation models and suitable processing parameters. Due to the high melt reactivity of liquid metals at high temperatures, measurements using conventional containers are challenging, hence containerless methods have to be used. Herein, the thermophysical properties of an Fe‐based metallic glass‐former have been measured in the liquid phase using the electromagnetic levitator ISS‐EML on‐board the International Space Station (ISS).

Surface Properties of Liquid Al-Ni Alloys: Experiments Vs Theory

The present study is an overview of the surface properties of liquid Al-Ni alloys, which are of great importance for the design and development of new Al-Ni and Ni-based industrial alloys, widely used as functional and structural materials. The solidification and thus, the microstructural evolution are directly dependent on the interface/surface properties of metallic melts. Therefore, numerical simulation of microstructure evolution requires reliable property data as input to such models. Taking into account the experimental difficulties related to a high reactivity of liquid Al-Ni alloys and the effects of impurities on their surface properties, the surface tension over the whole concentration range has been determined in the frameworks of three international research projects. Namely, the surface tension measurements have been carried out by both traditional container-based and as an alternative, containerless methods within the ESA-MAP ThermoProp and ESA-MAP Thermolab Projects and also under the EU FP6-IMPRESS Project. The obtained datasets were analysed and subsequently compared with the model predicted values as well as with the literature data. A strong exothermic mixing characterises the Al-Ni system and the presence of a few intermetallic compounds in the solid state leads to the formation of short range ordered elements or complexes in the liquid phase, at least near the melting temperature, which significantly affects the surface properties of alloy melts. Aiming to estimate the effects of short range ordering on these properties, the Compound Formation Model (CFM) and the Quasi Chemical Approximation (QCA) for regular solution were applied.

Melting temperature measurement of refractory oxide ceramics as a function of oxygen fugacity using containerless methods

AbstractAn aerodynamic conical nozzle levitator (CNL) has been used to measure the melting temperatures of refractory ceramics. The well‐established method of cooling traces has been adapted to allow measurements for air‐sensitive samples using a controlled atmosphere, where the oxygen partial pressure can be adjusted and monitored in real time. In this study, we explain the details of a system that we developed for use at the Spallation Neutron Source (Oak Ridge National Laboratory). Measurements of the melting behavior of (Fe,Cr,Al)3O4 spinels were made between log (PO2 (atm)) of −0.7 and −5. The melting temperature of hercynite is found to be oxygen potential dependent, ranging between 1692 and 1767°C at log (PO2) values from −4.42 to −0.70.

Non-contact methods for measuring the surface tension of liquids (review)

A review of non-contact methods for determining the surface tension of liquids along with analysis of the physical effects underlying them is presented. A review of non-contact methods for determining the surface tension of liquids along with analysis of the physical effects underlying them is presented. The advantages, disadvantages, possible ranges of measurements and scope of non-contact methods are discussed. Passive methods do not require any stimulation of the measurement object whereas active methods, when implemented, affect the liquid under study. Electrical, electromagnetic, acoustic, jet, and mechanical methods used for excitation of capillary waves are described in analysis of the methods based on capillary waves intended to study the properties of surface-active substances. We also considered methods based on the processes occurred in an oscillating or rotating levitating drop of liquid (containerless technology) used to study the properties of melts and methods based on local deformation of the liquid surface by the electric field, acoustic pulse, and gas jet. It is shown that aerodynamic methods based on deformation of the liquid surface under control by a gas stream are the most promising for standard laboratory conditions. It is noted that containerless methods should be used in zero gravity tests, whereas the methods based on capillary waves or deformation of the liquid surface with a focused acoustic pulse appeared useful in testing inviscid liquids. Methods based on electrical deformation of the liquid surface under control are limited with the thickness of the liquid layer, relatively high sensitivity to the density and dielectric constant of the liquid, and some other uncontrolled factors. It was also noted that aerodynamic non-contact method of the surface tension determination is characterized by low sensitivity to the density and viscosity of the controlled liquid. The presented review of non-contact methods of the surface tension determination provides optimal choice of the method most suited for solving specific measurement problems.

Large‐sized La2O3‐TiO2 high refractive glasses with low SiO2 fraction by hot‐press sintering

AbstractOwing to the ultrahigh refractive index, La2O3‐TiO2 glass is regarded as a promising candidate material in the field of lens, gemstones, and many other optics. However, due to its extremely low glass‐forming ability, it can only be obtained by rapid solidification processes such as melt quench or containerless solidification methods, leading to the limited size of as‐solidified products (for example, 1‐10 mm for containerless solidified sample), that are severely deferring the application of this novel high refractive glass. In this work, we aimed at preparing the larger sized bulk glasses over 10 mm, La2O3‐TiO2 glasses were successfully prepared by hot‐press sintering within the glass kinetic window. A small amount addition of SiO2 was found to effectively increase the glass‐forming ability while keeping high refractive index. When the content of SiO2 was 15 mol%, its transmittance could reach 54% at 800 nm and 72% in the infrared region (1 mm thick). Meanwhile, its refractive index could keep ultrahigh value above 2.14. And the sintering mechanism was studied according to the sintering shrinkage curve. It indicates that the plastic flow was the main mass transfer way in the densification process.

Using containerless methods to develop amorphous pharmaceuticals

BackgroundMany pipeline drugs have low solubility in their crystalline state and require compounding in special dosage forms to increase bioavailability for oral administration. The use of amorphous formulations increases solubility and uptake of active pharmaceutical ingredients. These forms are rapidly gaining commercial importance for both pre-clinical and clinical use. MethodsSynthesis of amorphous drugs was performed using an acoustic levitation containerless processing method and spray drying. The structure of the products was investigated using in-situ high energy X-ray diffraction. Selected solvents for processing drugs were investigated using acoustic levitation. The stability of amorphous samples was measured using X-ray diffraction. Samples processed using both spray drying and containerless synthesis were compared. ResultsWe review methods for making amorphous pharmaceuticals and present data on materials made by containerless processing and spray drying. It was shown that containerless processing using acoustic levitation can be used to make phase-pure forms of drugs that are known to be difficult to amorphize. The stability and structure of the materials was investigated in the context of developing and making clinically useful formulations. ConclusionsAmorphous compounds are emerging as an important component of drug development and for the oral delivery of drugs with low solubility. Containerless techniques can be used to efficiently synthesize small quantities of pure amorphous forms that are potentially useful in pre-clinical trials and for use in the optimization of clinical products. General significanceDeveloping new pharmaceutical products is an essential enterprise to improve patient outcomes. The development and application of amorphous pharmaceuticals to increase absorption is rapidly gaining importance and it provides opportunities for breakthrough research on new drugs. There is an urgent need to solve problems associated with making formulations that are both stable and that provide high bioavailability. This article is part of a Special Issue entitled “Science for Life” Guest Editor: Dr. Austen Angell, Dr. Salvatore Magazù and Dr. Federica Migliardo.

Further Development of Testing Procedures for High Temperature Surface Tension Measurements

A new testing procedure combining in one test two methods for surface tension measurements of liquid metals [the pendant drop (PD) and the sessile drop] and carried out in the same device is discussed. The attention is focused on methodological aspects of the PD method due to the novelty of its application for high temperature metallic systems. It has been claimed that under the conditions applied in the present study, this method can be considered as a quasi-containerless one. Surface tension measurements of pure Cu, Ni, Al, and Fe performed using the new procedure are described. To confirm the validity of this procedure, the experimental results are discussed in the framework of the available literature data, particularly those obtained by the containerless methods.

The Containerless Synthesis of Glass

Glasses are commonly synthesized by cooling melts at a rate sufficient to prevent the nucleation of substantial amounts of crystalline phases. In the limit, high cooling rates no longer prevent crystallization. In some of these cases, elimination of container‐melt‐induced nucleation by using containerless processing (also called levitation) significantly extends the glass‐forming composition range. Containerless methods also eliminate contamination allowing the preparation of high‐purity materials that can be used to benchmark properties and structure. This article briefly reviews the application of containerless methods to several types of glass. Some examples of glasses formed using containerless techniques are presented and discussed in the context of developing materials. A short commentary on specific issues that relate to the use of containerless processing is presented. This review is intended to provide an introduction to the use of containerless methods in glass research.

Thermophysical Property Measurements of Liquid Gadolinium by Containerless Methods

Thermophysical properties of liquid gadolinium were measured using non-contact diagnostic techniques with an electrostatic levitator. Over the 1585 K to 1920 K temperature range, the density can be expressed as ρ(T) = 7.41 × 103 − 0.46 (T − T m) (kg · m−3) where T m = 1585 K, yielding a volume expansion coefficient of 6.2 × 10−5 K−1. In addition, the surface tension data can be fitted as γ(T) = 8.22 × 102 − 0.097(T − T m)(10−3 N · m−1) over the 1613 K to 1803 K span and the viscosity as η(T) = 1.7exp[1.4 × 104/(RT)](10−3 Pa · s) over the same temperature range.

Surface Tension and Density of Liquid Metallic Alloys Measured by Electromagnetic Levitation

Reliable thermophysical data form the basis of any accurate solidification simulation. For the liquid phase of high-temperature metallic alloys, such data are scarce. In recent years, containerless methods, in particular electromagnetic levitation, have paved the way for noncontact measurement methods allowing precise determination of crucial thermophysical properties such as density, thermal expansion, and surface tension for this class of materials. Systematic investigations of the thermophysical properties of copper-based, nickel-based, and aluminum-based alloys have been carried out by the authors. This paper reviews the noncontact methodology used and provides a listing of the results obtained so far. Densities are discussed in terms of molar and excess volumes, whereas surface segregation is the key to understanding surface tensions of alloys.

A containerless levitation setup for liquid processing in a superconducting magnet

Containerless processing of materials is considered beneficial for obtaining high quality products due to the elimination of the detrimental effects coming from the contact with container walls. Many containerless processing methods are realized by levitation techniques. This paper describes a containerless levitation setup that utilized the magnetization force generated in a gradient magnetic field. It comprises a levitation unit, a temperature control unit, and a real-time observation unit. Known volume of liquid diamagnetic samples can be levitated in the levitation chamber, the temperature of which is controlled using the temperature control unit. The evolution of the levitated sample is observed in real time using the observation unit. With this setup, containerless processing of liquid such as crystal growth from solution can be realized in a well-controlled manner. Since the levitation is achieved using a superconducting magnet, experiments requiring long duration time such as protein crystallization and simulation of space environment for living system can be easily succeeded.

Thermophysical Properties of γ-Titanium Aluminide: The European IMPRESS Project

In the framework of its 6th Framework Programme, the European Union funds the Integrated Project IMPRESS, related to industrial applications of Ti-Al and Ni-Al alloys. One central task of this project is the precise determination of the relevant thermophysical properties of selected alloys for both the solid and liquid phases. The properties to be measured include thermal data such as heat of fusion, specific heat, and thermal conductivity, as well as thermophysical and transport properties such as density, surface tension, and viscosity. In addition to conventional high-temperature equipment, containerless methods are used. This article introduces the IMPRESS project, and discusses the first results obtained to date.

Solidification of Co-Cu Alloys in the Metastable Miscibility Gap under Low Gravity Conditions

Liquid Cu-Co shows a metastable miscibility gap where the homogeneous melt separates into the Co-rich L1-liquid and the Cu-rich L2-liquid. The required undercooling of the melt of > 120 K can be achieved by containerless methods as electromagnetic levitation, laser melting or drop tube processing. Due to the large undercooling, rapid solidification of the melt is favoured and preserves microstructure features of the metastable (liquid) phases. In Co-84.0 at% Cu alloy the L1- phase nucleates in the Cu-rich majority phase L2 as a dispersion of spherical droplets. Convective flow in the liquid influences largely the time evolution and the nature of the droplet dispersion and makes a theoretical description of the droplet growth extremely difficult. In the present work droplet dispersions are compared which formed under processing methods with different levels of convection: (i) (Terrestrial) electromagnetic levitation (EML), (ii) processing in the TEMPUS facility under parabolic flight conditions and (iii) processing in an 8 m drop tube. The distributions of droplet radii of the L1-phase has been measured in the solidified samples. EML processing leads to significant convection in the melt which causes coagulation of droplets. Reduced gravity conditions in the TEMPUS facility during parabolic flight or in a drop tube can decrease convection, but effects of the convective flow on the dispersion of droplets are still present. The need for experiments under micro-gravity conditions is evident from the results.

「最新の無容器技術による高温融体の物性測定とプロセス」の企画にあたって

「最新の無容器技術による高温融体の物性測定とプロセス」の企画にあたって

Thermophysical Property Measurements of Liquid and Supercooled Iridium by Containerless Methods

Thermophysical properties of equilibrium and supercooled liquid iridium were measured using noncontact diagnostic techniques in an electrostatic levitator. Over the 2300–3000 K temperature range, the density can be expressed as ρ (T)=19.5×103 − 0.85(T− Tm) (kg·m−3) with Tm=2719 K. The volume expansion coefficient is given by 4.4 × 10−5 K−1. In addition, the surface tension can be expressed as γ (T)=2.23 × 103 − 0.17(T−Tm)(10−3N·m−1) over the 2373–2833 K span and the viscosity as η(T)=1.85 exp [3.0× 104/(RT)](10−3Pa·s) over the same temperature range.

Thermophysical Properties of Undercooled Metallic Glass Forming Liquids

Non-contact thermophysical property measurement of liquid metallic alloys is rapidly developing as a response to the increased need of precise thermophysical data for industrial as well as for scientific applications. The paucity of. such data is mostly a result of the experimental difficulties arising from the unwanted convection and chemical reactions of liquid metals with containers at high temperatures. An overview will be given of the state of non-contact calorimetry and thermal transport property measurement based on electromagnetic induction and on typical results obtained during several different space flights using containerless processing methods. Furthermore, a perspective on a future measurement program of thermophysical properties supported by the European Space Agency is described. In this regard, the International Space Station is considered as the ideal laboratory for high precision measurements of thermophysical properties of fluids, which will help to improve manufacturing processes for a number of key industries.