INFLUENCE OF EVAPORATION AND HYDRODYNAMICS EFFECTS ON SURFACE MODIFICATION OF METALS UNDER THE ACTION OF COMPRESSION PLASMA FLOWS

摘要

Use of compression plasma flows opens wide possibilities for modification of metals and semiconductors by creating deep uniformly doped surface layers with elevated service characteristics. In the present work, evaporation and hydrodynamic effects in metals (iron, copper, aluminum) under the action of compression plasma flows are studied theoretically and experimentally. In experimental onditions, plasma flows were generated by employing a magnetoplasma compressor of compact geometry with storage battery energy of 15 kJ. The lifetime of stable plasma flow was 100 μs. It was found that at a power density of 5-12 GW/m~2 intense ablation of material from the metal surface occurs. Modeling of heat transfer processes on the basis of the Stefan problem with account for melting and evaporation showed that the observable ablation of material cannot be explained only by evaporation. It was found experimentally that hydrodynamic removal of metal in a liquid state under high plasma flow pressure (10-30 atm) makes a substantial contribution to the total ablation. The proportion of hydrodynamic removal grows with increase of the plasma flow power density.