Gas-jet synthesis of diamond-like films from an $\mathrm{H}_2+\mathrm{CH}_4$ gas mixture glow

Synthesis of diamond-like coatings from a high-velocity flow of gas mixtures in flow regimes from free-molecular to continuum with flow velocities from hundreds to thousands meters per second at different specific flow rates and temperatures in the case of activation of gases on hot surfaces is studied experimentally. Deposition of carbon films at low (less than 0.15 Pa) and high (2600 Pa) pressures from a mixture of hydrogen and methane is considered. The hydrogen flow is computed by the Direct Simulation Monte Carlo (DSMC) method in accordance with test conditions with given surface temperatures and chemical transformations on the surfaces. It is found that coatings obtained at the high pressure contain particles typical for diamonds and unusual inclusions shaped as prisms with a hexagonal cross section.