Cutting Tools Nitriding in Plasma Produced by a Fast Neutral Molecule Beam

Nitrogen plasma produced by a broad beam of fast neutral nitrogen molecules in 0.12-m3 vacuum chamber has been studied and used for cutting tools nitriding. The study results prove that fast molecules play a leading role in gas ionization and plasma density is proportional to their energy, equivalent current and gas pressure. Plasma is quite nonuniform: its density is maximal within the beam and rapidly decreases beyond it. Non-self-sustained glow discharge between chamber and an anode immersed in the plasma reduces plasma nonuniformity down to 10%, when discharge voltage amounts to 200–300 V, and raises plasma density by an order of magnitude. After 1-h-long soaking in discharge plasma of isolated from the chamber and heated by 4-keV beam up to 500 °C cutting plates made of high-speed steel their microhardness rises from 950 up to 1400 HV, and the mean radius of cutting edges decreases from 20 to 18 µm.