Liquid Carbon Properties Against Input Energy Only

Abstract

The main discussed results were obtained at the high pressure (14–94 kbar) under slow (millisecond) heating by electrical current (Togaya et al.) during 1997–2010 years. In spite of the fact that only resistivity and enthalpy were measured the authors gave an important conclusion on the appearing liquid state of carbon and on the dependence of resistance versus pressure. Liquid carbon (at the melting point) diminishes its resistance at a pressure lower 50 kbar, and resistance rises at a pressure higher 50 kbar. American scientists (Gathers et al.) obtained experimental data under microseconds heating, that graphite is compacted even in a solid phase, reaching its maximum density near the input energy ∼7.5 kJ/g (that is before melting). Thus, graphite of low initial density compacts to the maximum density (2.2 g/cm3) in the time interval shorter than 1–2 microseconds, and then reaches melting point just as usual graphite of high initial density. The third part of this chapter (also microseconds heating) shows the behavior of resistance for different graphite grades under thermo-compression in sapphire capillary tubes. Korobenko and Savvatimskiy (JIHT, Russia) obtained the data on expansion of carbon at fast microseconds heating and estimated the resistivity of carbon near melting with an expansion included. A detailed data on resistivity versus input energy under fast heating of isotropic graphite MF-307 (Japan production) are discussed. It was mentioned a critical sensitivity of graphite to the start of melting under rising pressure. It was discussed the role of pinch pressure for graphite melting (except its surface). Discovered a critical sensitivity of graphite melting to the magnitude of applied pressure (experiments for graphite sticks heated inside sapphire capillary tubes).