Pulsed plasma-oxidation of nitrided steel samples
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Plasma nitrided/nitrocarburized samples made of steel grade DIN C15 were post oxidized in a mixtures of H-2 and O-2 gases using pulse power supply. Plasma nitrocarburizing post-oxidation were performed at 520 degreesC. The applied process is a combination of plasma nitriding, plasma nitrocarburizing and plasma-oxidation of the compound layer. Pulse plasma was used in all process steps at 5 kHz frequency and pause/pulse ratio 1:19. The XRD examination revealed the existence of the compound zone composed of of the gamma or gamma+ epsilon carbonitride phase with a thin overlayer of magnetite Fe3O4. The architecture of formed surface structure provides the unique mechanical and tribological properties with the diffusion zone responsible for load bearing capacity, wear and fatigue resistance and the double compound layer resistant to wear and corrosion. The results of Vickers microhardness measurements, optical microscopy, XRD and SEM analyses were presented. The obtained surface structures... were compared with the samples salt bath nitrided in a conventional industrial unit. (C) 2003 Elsevier Science B.V. All rights reserved.
Keywords:plasma nitriding / plasma nitrocarburizing / salt bath nitrocarburizing / post oxidation / pulse plasma
Source:Surface and Coatings Technology, 2003, 174, 1220-1224
- 8th International Conference on Plasma Surface Engineering, Sep 09-13, 2002, Garmisch Partenki, Germany