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Open AccessArticle

Surface Hardening of Massive Steel Products in the Low-pressure Glow Discharge Plasma

Department of High-efficiency Machining Technologies, Moscow State University of Technology "STANKIN", Vadkovsky per. 3A, 127055 Moscow, Russia
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Technologies 2019, 7(3), 62; https://doi.org/10.3390/technologies7030062
Received: 15 July 2019 / Revised: 19 August 2019 / Accepted: 27 August 2019 / Published: 28 August 2019
(This article belongs to the Special Issue Processing and Fabrication of Advanced Materials)
A process vacuum chamber is filled with a homogeneous plasma of glow discharge with electrostatic electron confinement, which is used for surface hardening of massive products. At the current of 2–20 A and the gas pressure ranging from 0.1 to 1 Pa the discharge voltage amounts to 350–500 V. When a bias voltage of 2 kV is applied to an immersed in the plasma hollow cylinder with a mass of 15 kg, electrical power spent on heating it by accelerated ions exceeds by an order of magnitude the power spent on the discharge maintenance. The massive cylinder is heated up to 700 °C for 15 min. When argon mixture with nitrogen (30%) is used, the nitriding for 3h results in an increase in the surface hardness from 400 up to 1000 HV50 and the nitrided layer thickness grows to ~100 μm. The nitriding rate is enhanced by a high degree of nitrogen dissociation due to decomposition by fast electrons and surface structural defects due to bombardment by high-energy ions. View Full-Text
Keywords: glow discharge; electron confinement; plasma homogeneity; nitrogen dissociation; structural defects; nitriding rate glow discharge; electron confinement; plasma homogeneity; nitrogen dissociation; structural defects; nitriding rate
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Grigoriev, S.; Metel, A.; Volosova, M.; Melnik, Y.; Ney, H.A.; Mustafaev, E. Surface Hardening of Massive Steel Products in the Low-pressure Glow Discharge Plasma. Technologies 2019, 7, 62.

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