A. Savvatimskiy
Sep 7, 2015
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Carbon at High Temperatures
Abstract
Astrophysical and terrestrial aspects of carbon investigations are discussed. Carbon and diamond structures are shown in comparison. A practical role of carbon in industry is underlined. The clue steady state experimental studies (starting with 1911 year), was discussed up to 1963 year. Particularly the estimation data of Leipunskiy (Russia) are shown to obtain diamond at high pressure (more than 40 kbar) for carbon with dissolved iron and at elevated temperature (higher 1500 K). 1.1 Astrophysical and Terrestrial Aspects of the Carbon Study Carbon is a unique element of the periodic table, it is formed a huge amount of carbon compounds on the basis of carbon. Organic chemistry as a science emerged due to the existence of carbon. Not coincidentally, it belongs to the boundary matter between living and nonliving matter. One form of carbon—graphite is among the most refractory substances, which explains its widespread use in the industry. Construction of a complete phase diagram of carbon at high temperatures has always been the aim of the experimenters, because it allowed them to predict the properties required for practical applications. Modern energy industry, including pulse technique, required knowledge of the physical properties of carbon at high temperatures, normally comprised its liquid state. To solve this problem has not been enough steady state research methods, as for crucible there is no more refractory matter than the graphite itself. Transient research methods (rapid heating by laser or electric pulse current); have been intensively developed for several decades, first to study metals, and then graphite. The main problem under this study remains the measuring a true temperature of the specimen. There is evidence that for polycrystalline metals fast heating (up to fractions of a microsecond) may obtain, in general, the equilibrium thermal properties (enthalpy of the solid and liquid phase, heat capacity, heat of fusion) as well as temperature. Under graphite © Springer International Publishing Switzerland 2015 A. Savvatimskiy, Carbon at High Temperatures, Springer Series in Materials Science 134, DOI 10.1007/978-3-319-21350-7_1 1 heating there are more significant features related to: its complex structure (anisotropy), sublimation of the solid phase, the density dependence of the manufacturing process, the initial heterogeneity of structure, etc. These features affect the measurement of temperature of graphite, especially near the melting point. Motivation for scientists to study carbon has two major components: (1) astronomy and (2) the practical needs of space exploration and development of nuclear technology. We denote these two areas in more detail. (1) The planets of our solar system (Mercury, Venus, Earth and Mars) are composed of silicates based on silicon. However, as was predicted by astronomers in 2005 [1] may exist planets consisting mainly of carbon. Theorists M. Kuchner, (Princeton University) and S. Seager (Carnegie Institution of Washington) presented a model in which some exoplanets (planets orbiting their stars) may consist mainly of carbon compounds. Carbon planets are more common in the center of the galaxy, because the carbon concentration is higher than near the solar system. Carbon planets contain carbon in various phase states. Kuchner and Seager believe that their idea is consistent with the discoveries of planets located close to their parent stars—much closer than Mercury is to the Sun. In such a planet, they argue, significantly more likely to survive at high temperatures near the star. Exoplanets revolve around stars (such as stars already discovered more than a hundred); most of them must contain a large amount of carbon, as resulted from the condensation of coal dust and gas rich in carbon. They may consist of solid carbon components, including silicon carbide SiC. On such planets cannot be excluded deposits of almost pure carbon. The upper layers of carbon deposits can be graphite, and the lower (due to pressure)—diamond. Experimental confirmation of the existence of carbon planets appeared in 2010 [2]: an analysis of multi-wavelength photometry of the exoplanet WASP-12b showed a high concentration of carbon in the atmosphere. Recent images of Titan—Saturn obtained with the probe “Huygens” shows that the Methane Rivers and lakes are on its surface. Astrochemical Katharina Lodders from Washington University in St. Louis, Missouri, suggested that methane-rich atmosphere of Jupiter—proof that the planet was formed around of the carbon-based nucleus. The knowledge of the properties of carbon at high pressures and temperatures is one of the main problems in the physics of extreme conditions. (2) Relevance of research on the properties of carbon depends on the fact that carbon and its compounds are increasingly used as structural materials for scientific and industrial high-temperature devices. For example, the development of space launch programs directly related to the search for new materials that can withstand significant thermal load (protective tiles on the “Buran-rocket”; nosecone missiles whose temperature reaches more than 3000 K at the entrance to the Earth’s atmosphere, and finally, the exhaust nozzle of the last missiles of the latest pattern. Nozzle of up-to date missiles performed on the basis of carbon compounds must to withstand a temperature 2 1 The First Attempts of Carbon Melting and Obtaining Diamond ...