Yury A. Melnik

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.

New Method for Synthesis of Hard Coatings Using Pulsed Bombardment with High-Energy Gas Atoms

For deposition of hard coatings is used a source of metal atoms accompanied by high-energy gas atoms. The metal atoms are produced due to sputtering a flat rectangular target in low pressure magnetron discharge. The gas atoms with energy up to 30 keV are produced due to charge exchange collisions of accelerated ions in space charge sheaths near the surfaces of a grid parallel to the target. The ions are extracted from the discharge plasma and accelerated by high-voltage pulses applied to the grid. The metal atoms pass through the grid and deposit on the products. Conjunction of their trajectories with those of gas atoms bombarding the growing coating allows synthesis of the coatings on rotating dielectric products. Mixing by high-energy gas atoms of the coating atoms and atoms of the product material in its surface layer improves the coating adhesion.

Effective Sputtering System for Deposition of Wear-Resistant and Anticorrosion Coatings

Results of a target sputtering investigation have been obtained, the target being positioned on the bottom of a cylindrical hollow cathode covered by a grid. It was shown that influence on the glow discharge of a nonuniform magnetic field with lines crossing the target center as well as the grid, the hollow cathode and the target periphery, where the field lines are arc-shaped, depends on the magnetic induction on the target edge. Due to ionization by electrons emitted by the cathode and forced by the magnetic field to approach to the target more frequently the plasma density near the target grows up and more than a half of all ions produced in the discharge quite uniformly sputter the target