Effect of tungsten carbidization on gas activation in synthesis of diamond structures

With the aim of developing a gas-jet technique for depositing diamond structures, the flow of a hydrogen–methane mixture through hot coaxial tungsten cylindrical channels with a tungsten coil inside has been investigated. Emphasis has been placed on tungsten surface carbidization during gas-jet deposition and the influence of carbidization on the deposition rate and morphology of applied coatings. Several experiments on tungsten surface carbidization under different conditions for hydrogen–methane mixture supply have been conducted. Simulation of the mixture flow by direct simulation Monte Carlo method has been performed. Possible ways of how methane and its fragments fall on the surface of the coil has been discussed.