| 书目名称 | Materials Sciences in Space | | 副标题 | A Contribution to th | | 编辑 | Berndt Feuerbacher,Hans Hamacher,Robert J. Naumann | | 视频video | | | 图书封面 |  | | 出版日期 | Book 1986 | | 关键词 | crystal; design; diffusion; dispersion; electron; fluid dynamics; glass; materials; materials science; metals | | 版次 | 1 | | doi | https://doi.org/10.1007/978-3-642-82761-7 | | isbn_softcover | 978-3-642-82763-1 | | isbn_ebook | 978-3-642-82761-7 | | copyright | Springer-Verlag Berlin, Heidelberg 1986 |
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Front Matter |
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Abstract
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Abstract
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Introduction |
B. Feuerbacher |
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Abstract
The development of space exploration and astronautics has undergone a major change in scope during the early eighties. This is quite apparent from the availability of a new space transportation system, the space shuttle, which offers a large cargo capability to low earth orbits with the novel features of full payload recoverability and nearly regular, frequent service. Along with this, a number of other aspects changed more gradually and less apparent. The role of man in space has shifted from a mainly technical piloting function to a much more active involvement, including scientific tasks and interactive work in space. This is illustrated by Figs. 1.1 and 1.2, contrasting the rather clumsy appearance of Astronaut Aldrin on the lunar surface during the Apollo 11 mission with the hands-on work of Payload Specialist Lichtenberg in the shirt-sleeve environment of Space!ab during STS-9.
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Historical Development |
R. J. Naumann |
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Abstract
This chapter outlines the history of the U.S. Microgravity Science and Applications program from its beginning as strictly an applications program aimed at developing space manufacturing processes for commercial use, through its metamorphosis as a material science program, to its present status as a microgravity science program. Significant findings of the early flight experiments are summarized.
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Simulation of Weightlessness |
H. Hamacher |
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Abstract
The phenomenon of gravitation is characterized by the mutual attraction of any two bodies. The universal character of gravitation was first recognized by Isaac Newton who found the well-known law for the attraction force F acting between two mass points or homogeneous spherical bodies . M, m are the masses, γ = 6.67·lO. Nm.kg. the universal gravitational constant and R the distance of the centers. The weight of a body of mass m is related to the gravitational acceleration g of the earth by W = mg. Assuming an ideally central gravitational field for the earth, Eq. (3.1) yields for points outside the earth periphery . where g. = γM./R.. = 9.81 ms. is the gravitational acceleration at the earth surface, usually called 1 gravity or lg. M. = 5.97·10.kg and R. = 6.371·10. m are mass and mean equatorial radius of the earth, respectively.
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Convection and Bulk Transport |
Robert A. Brown |
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Abstract
Probably the most alluring prospect of performing experiments in a low-gravity environment is the ability of freeing an experiment from the action of the earth’s gravity, which although constant and of known direction, has pronounced effects on the processing of fluids and gases. The most important effects of gravity are the impossibility of levitating a fluid mass isolated from solid surfaces and the consequences of buoyancy-driven-convection caused by gradients of temperature and concentration in the fluid. It was recognized over a decade ago that the large reductions in gravity possible aboard an orbital spacecraft will remove these two effects and lead to new experiments and, possibly, to the development of new methods for processing materials. In conjunction with the enormous interest in experimental research in a low-gravity environment, many new analyses have been reported that add to the understanding of transport phenomena both on earth and in space relevant to the design and intepretation of these experiments.
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Diffusion and Atomic Transport |
G. Frohberg |
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Abstract
Diffusion is a common phenomenon in gases, liquids and solids. The diffusion coefficient, describing these processes, is typically of the order of 1 cm./s for gases, 10. cm./s for liquids and normally lower than 10.cm./s for solids. Diffusion in gases, of lower practical interest in the field of material science, is well understood in terms of the kinetic gas theory. On the other hand, much experimental and theoretical interest is concentrated on diffusion in solids and in this field many new and fine tools have been introduced in diffusion investigations in the last decades.
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Capillarity and Wetting |
J. M. Haynes |
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Abstract
Interfacial phenomena, originating at boundaries between phases, have a profound influence on the behaviour of matter. The excess of energy associated with the existence of an interface gives rise to the force of ., which results in a general tendency for conterminous phases to adjust the areas of their common boundaries, either to a minimum or to a maximum, the first representing . hydrostatic equilibrium, and the second .. Extremization of this excess energy may also lead to a redistribution of material components in the iimediate vicinity of an interface — the phenomenon of .. The curvature of interfaces imposes a mechanical equilibrium condition which implies, in turn, an influence on the chemical potential of material components in the system. Here again, equilibria may be stable or unstable. In systems involving active material transport, . can be of major interest.
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Solidification |
P. R. Sahm,J. C. Sturm |
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Abstract
Solidification on Earth is always linked to complex interactions of the various heat and mass transport processes. The amount of diffusive and con-vective phenomena, especially in the vicinity of the liquid-solid interface, take a strong influence on the microstructure and the resulting properties. Therefore a key of reproducible solidified microstructures at increasingly higher levels of control is a better understanding of the interactions between fluid mechanics and the liquid-solid interface.
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Nucleation and Undercooling |
D. M. Herlach,B. Feuerbacher |
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Abstract
Nucleation plays an important role in many processes involving phase changes, such as boiling, condensation, cloud formation, solidification, defect formation etc. Even though it is not invoked in the formation of a-morphous solid phases, nucleation dynamics is an essential ingredient into our understanding of glassy solidification. Nucleation effects occur whenever the free energy of a phase formed in a transformation process becomes size dependent, and they lead invariably to the phenomenon of undercooling. The latter is a non-equilibrium process which gives access to areas in the phase diagram not accessible to equilibrium systems.
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Critical Phenomena |
D. Beysens |
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Abstract
Critical Phenomena is a part of Physics which has developed rapidly over the last 15 years, as exempled by the 1982 Hobel price for Physics which was awarded to K. Wilson for his major contribution in the field. Indeed the domain covered by this field is very large. The concept of a 2. order phase transition, which is detailed below, allows many different phenomena encountered near a transition to be considered as being equivalent and so they can be formulated by the same universal laws. This universality applies to both the . — not only critical points are involved but also percolation, fractals, etc. — and the .. Indeed a very large number of physical systems, such as simple fluids, binary. or multicomponent fluid mixtures.- including metallic liquid mixtures -, liquid crystals, microemulsions, polymers, molten salt, alloys., superfluid Helium, magnets, ferroelectrics, etc. exhibit the same universal behaviors. These systems can be classified into a few “universality classes”, according to very simple criteria as we will see below. In the following we will mostly deal with the “class” of ..
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Abstract
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Furnaces |
Wolfgang Steinborn |
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Furnaces for Materials Processing in space as well as on the ground perform according to one or more of the three heating principles:
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Fluid Experiments |
Alain Gonfalone |
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Abstract
This chapter contains a brief description of techniques for measuring fluid properties current in space. A selection of instruments representative of the latest technology are presented and briefly described. Some of these instruments have already been flown. The scientific results that have been obtained with them are reported by Langbein in Chapter 16 and elsewhere [11.1], and will not be discussed here in any detail.
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Containerless Processing Technology |
R. J. Naumann,D. D. Elleman |
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Abstract
The virtual absence of hydrostatic pressure in a microgravity environment allows liquids to be confined solely by their surface tension and offers the possibility of melting and solidifying materials without physical contact. This “containerless processing” eliminates contaminants that may be introduced by the container or crucible and may be used to obtain ultrapure materials. This is especially important for systems that are highly corrosive in the melt. Elimination of container-induced nucleation also permits melts to be deeply undercooled before solidification. This offers the possibility of studying homogeneous nucleation and solidification in undercooled melts. Such solidification can be extremely rapid and may produce unique microstructures including metastable or amorphous phases in metals. The range of glass formation may be extended in borderline glass forming systems, which may result in new glasses with unusual properties. Since such glasses are formed from melts confined only by surface tension, they will have perfectly spherical pristine surfaces, undamaged by grinding or other shaping processes. It may also be possible to manipulate the melt to form aspherical shapes
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Metals and Composites |
J. J. Favier |
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Abstract
Metallurgy was from the very beginning one of the most promising domains of potential applications for space experimentation. In fact one of the first problems considered in the context of the microgravity environment was its capability to modify the procedure for brazing or welding in space when repairing spacecraft or assembling metallic structures in orbit. Later on, the opportunity was envisaged to use the specific microgravity conditions a board satellites in orbit for improving metallurgical processes. This was the situation when the first experiment opportunities emerged aboard SKYLAB in the early seventies. A few years later, in 1975, the call for proposals for the first Spacelab Mission found the European Scientific Community in the same feeling. Some scientists, however, considered this as an opportunity to test more fundamental material science concepts and to improve our basic knowledge in metallurgy. This position was reinforced with the low cost — low technological investment-rocket flight opportunities offered by the SPAR programme in the United States as well as the TEXUS programmes in Germany and later with the European Space Agency.
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Binary Systems with Miscibility Gap in the Liquid State |
Berndt Feuerbacher,Hans Hamacher,Robert J. Naumann |
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Abstract
Systems with miscibility gap in the liquid state, “immiscibles”, are of fundamental interest and have potential for the preparation of dispersions. The study of these systems and their application has, thus far, been very limited. Under terrestrial conditions the liquid components separate quickly due to sedimentation and buoyancy. Component separation due to nucleation and growth of nuclei and spinodal decomposition can, therefore, not be studied under defined conditions and fine dispersions cannot be prepared. Research under microgravity conditions in orbiting laboratories or under free fall conditions opens new avenues for the study of these systems. This paper summarizes the underlying thermodynamic and physical principles and mechanismes and reviews results of recent experimental investigations.
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Crystal Growth |
D. T. J. Hurle |
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Abstract
Improved chemical homogeneity and structural perfection are the main goals for crystal growth in space and the results of experiments in melt, solution and vapour growth are reviewed. Future prospects and requirements are indicated.
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发表于 2025-3-21 16:46:38
