Quenching of liquid carbon under intensive heat transfer to the cold diamond substrate: Molecular-dynamic simulation

Abstract

Quenching of liquid carbon (T = 6600 K) on a cold diamond substrate at T = 300 K in conditions close to the experimental laser melting of dispersed graphite on the substrate of natural diamond is investigated using molecular dynamics (MD) simulations. Quenching was carried out for two types of boundary conditions on the side opposite to the diamond substrate. The simulations confirmed the experimental result of the formation of amorphous carbon under such conditions. The calculations showed that the destruction of the diamond substrate did not take place because of its very high thermal conductivity. The estimation of the cooling rate of liquid carbon was done, the result is 1015 K/s. Temperature profiles in different layers of liquid carbon were restored to reproduce the detailed picture of the quenching process. We evaluated the radial distribution functions (RDF), the distribution of carbon atom bond fractions sp1-sp2-sp3, the average bond length and the azimuthal angles distributions for amorphous carbon atoms. This analysis confirmed that the amorphous carbon obtained by quenching in MD-simulations had a graphite-like structure.