Controlling nitrogen dose amount in atmospheric-pressure plasma jet nitriding

Ryuta Ichiki, Masayuki Kono, Yuka Kanbara, Takeru Okada, Tatsuro Onomoto, Kosuke Tachibana, Takashi Furuki, Seiji Kanazawa

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


A unique nitriding technique with the use of an atmospheric-pressure pulsed-arc plasma jet has been developed to offer a non-vacuum, easy-to-operate process of nitrogen doping to metal surfaces. This technique, however, suffered from a problem of excess nitrogen supply due to the high pressure results in undesirable formation of voids and iron nitrides in the treated metal surface. To overcome this problem, we have first established a method to control the nitrogen dose amount supplied to the steel surface in the relevant nitriding technique. When the hydrogen fraction in the operating gas of nitrogen/hydrogen gas mixture increased from 1% up to 5%, the nitrogen density of the treated steel surface drastically decreased. As a result, the formation of voids were suppressed successfully. The controllability of the nitrogen dose amount is likely attributable to the density of NH radicals existing in the plume of the pulsed-arc plasma jet.

Original languageEnglish
Article number714
Issue number6
Publication statusPublished - 2019 Jun


  • Atmospheric-pressure plasma
  • Hydrogen fraction
  • Nitrogen dose amount
  • Plasma nitriding
  • Void


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