Peter M. Schanin

The structure and phase composition of prehardened 38CrNi3MoVN steel subjected to an electron beam treatment have been studied by the metallographic, scanning, and transmission electron microscopy. The e-beam parameters are as follows: the energy of accelerated electrons U ~ 15 keV, the beam current I ~ 60 ?, the current pulse duration t ~ 30 µs, the pulse repetition rate f ~ 1 Hz, the beam diameter in the specimen surface plane D ~ 1.6 cm, and the beam energy density E_S ~ 10 J/cm². The e-beam treatment of the material has been shown to result in a gradient structure whose characteristic feature is a considerable (tenfold) decrease in the average size of martensite crystallites and laths with attended increase in the steel surface layer hardness by a factor of 2.5−3.

This paper presents the results of investigation into the generation of a gas-discharge plasma by an arc source with a cold hollow cathode. The source produces a plasma of density ~1010-1011 cm-3 in a volume of ~0.5 m3 at a discharge current of up to 120 A, a discharge operating voltage of 30-40 V, and at a pressure of 0.1-1 Pa. The motion of a cathode spot in crossed electric and magnetic fields inside the hollow cathode and a special cathode design make it possible to preclude almost completely the penetration of the sputtered cathode material into the working chamber and to increase the lifetime of the cathode. Because the cathode spot operates at an integrally cold surface of the hollow cathode, the source allows generation of a chemically active gas plasma.

Research on a hollow-cathode non-self-sustained glow discharge demonstrates the feasibility of discharge operation at pressures from 0.1 Pa. Depending on experimental conditions, the discharge operating voltage can reach ~50 V, which is much lower than that of a self-sustained glow discharge in the same electrode system. The discharge current can range up to 30 A. The working gas is Ar, N₂, and N-based gas mixtures. Probe measurements of the discharge plasma show that the electron temperature varies between 1.5 and 7 eV, depending on the pressure of gas and its kind, and the plasma density can reach 10¹¹ cm⁻³ at 15-A currents. Nitriding in the discharge plasma at 600°C for 2 h made it possible to increase the hardness of Ti (VT1-0) 3.5 times and that of 12Cr18Ni10Ti three times, with a modified layer depth of 35 µm.

Self-sustained glow discharge with a hollow cathode was studied at high discharge currents (up to 30 A). Using a grid analyzer placed on the side flange of the hollow cathode, the ion and electron...

The article presents the results of an investigation into the influence of the composition of a plasma-forming gas (N2, Ar, He) on nitriding of VT1-0 grade titanium (0.25%-Fe; 0.1%-Si; 0.2%-O) and...

This paper presents the results of experimental studies of a new design of discharge system using a self-heated hollow cathode. The discharge system offers certain advantages that are attractive for use in high-dose ion implantation, plasma generators, and plasma electron sources.

The effect of the intensification of electron emission in a plasma-cathode diode with a grid-stabilized plasma boundary has been investigated. For a pulsed (100-mus) electron beam of 15-20-keV energy that passes through the plasma formed as a result of gas ionization by an electron beam, it has been revealed that an increase in pressure increases the emission current at a fixed plasma-cathode discharge current, and the emission current can become greater in magnitude than the discharge current. It has been shown that a significant increase in electron-beam current is provided by the secondary ion-electron emission that results from the bombardment of the emission electrode surface by the accelerated ions coming from the boundary of the anode plasma.

The process of nitriding at low pressures and temperatures (≤550°C) in hollow-cathode glow discharge plasma was studied for technical-purity titanium of the VT1-0 commercial grade. The diffusion saturation of titanium with nitrogen in plasma with a concentration of n = 10¹⁰–10¹¹ cm⁻³ takes place at an ion current density on the cathode within 1.6–4.0 mA/cm². It is established that a key role in the process of metal saturation is played by atomic nitrogen. The experiments revealed the formation of a layer of gradient structure with a high microhardness (∼14 GPa) on the surface of nitrided titanium.