Surface hardening by means of plasma immersion ion implantation and nitriding in glow discharge with electrostatic confinement of electrons

Abstract

At argon or nitrogen pressure 0.005-5 Pa a metal substrate is immersed in plasma of glow discharge filling a vacuum chamber and negatively biased to U = 1-10 kV. Emitted by substrate secondary electrons bombard the chamber walls and it results in growth of electron emission chamber walls and rise of gas ionization intensity inside chamber. At pressure p< 0.05 Pa nonuniformity of plasma density does not exceed ~10%. Measurement results of sheath width d between homogeneous plasma and a lengthy flat substrate were used to calculate dependence of the ion current density ji on its surface and ion-electron emission coefficient γi. The dependence allows evaluation of average dose of ion implantation on any complex-shaped product of the same material.