Methods of increasing the measurement accuracy during the experimental determination of the melting point of graphite

The experimental procedure involving pulsed laser heating is realized, which enables one to investigate phase transformations in graphite and eliminates the homogeneous condensation of carbon vapor over a sample. Data are obtained on the melting point of graphite and the temperature of crystallization of liquid carbon at a pressure of $15$ MPa. The absence of a difference between the melting point of graphite at a heating rate of $100$ MK/s and the temperature of crystallization of liquid carbon at the cooling rate of the melt bath of $1.6$ MK/s is revealed, which is indicative of the quasi-equilibrium of the melting process. In view of this, the temperature data are averaged by a unified value of $4800\pm100$ K. It is shown that, during the crystallization of carbon melt, highly ordered graphite with crystallites up to $250\mu$m in size is formed in a liquid film $5\mu$m thick on a graphite substrate.