| 摘要 |
The present invention refers to a plasma reactor coupled with a microwave post discharge. The concurrence of ionized species and neutral but activated species generated from a microwave post discharge allow nitrogen to be diffused in tool grade steel pieces and the subsequent formation of a hard layer of nitrides. The piece to be nitrided constitutes the cathode of the reactor, which is placed into a chamber where a 10-3 Pa vacuum is carried out by means of a mechanical pumping system. The walls of the piece are connected to ground and the piece to be treated to a 600V negative potential, in this environment a plasma that is slightly ionized is produced about the said piece. For the purpose of improving the reaction, a flow of neuter species that are vibrationally excited or dissociated is transported to the surface of the piece. The reactivity of the medium is controlled by means of a molar fraction of N2, H2 or Ar contained in the mixtures to be combined with the substrate. The temp erature of the piece is controlled by means of the potential difference applied to the sample. Diverse operational parameters have been determined in the process so as to generate hardness profiles, which depend on depth.
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