Nitriding of a tool steel with an electron-beam-excited plasma

Abstract

Nitriding of a tool steel was carried out with an electron-beam-excited plasma (EBEP). EBEP is sustained with energetic electron beams over the pressure range of 10−3–101Pa by electron-impact ionization. Samples whose temperatures were controlled by electric radiant heater were exposed to EBEP. A nitrided layer of 100μm and a surface hardness of 1000HV(0.1) were achieved for tool steel SKD61 (JIS) at 800K and a treatment time of 3h. In order to measure the density of nitrogen atoms in EBEP, a vacuum ultraviolet absorption spectroscopy system was used. It was found that the density of nitrogen atoms increased from 1011to1012cm−3 linearly with an increase of electron beam current from 2to20A.