EFFECT OF HYDROGEN CONCENTRATION IN ARGON-HYDROGEN MIXTURES ON PARAMETERS OF ELECTRIC-ARC IN GAS-VORTEX PLASMATRONS FOR DIAMOND COATING SYNTHESIS

Experiments have been performed to investigate the influence of hydrog en concentration in argon-hydrogen mixtures on are discharge parameter s of a gas-vortex plasmatron with gas-dynamic fixing of the are length for synthesizing diamond coatings (DC) at different argon flow rates. A phenomenological explanation is offered to account for the dependen ce of the are voltage drop on hydrogen concentration in the argon-hydr ogen mixture for fixed are current and argon flow rate values. It is s hown that increasing the argon flow rate at a constant hydrogen flow r ate increases the specific enthalpy and the temperature of hydrogen. A n experimental method of determining the optimum hydrogen concentratio n in the argon-hydrogen mixture of the are discharge used for DC synth esis at different are current values is proposed. (C) 1998 Elsevier Sc ience S.A.