PROCEDURE FOR PLASMA NITRIDING ITEM OUT OF STEEL OR NON-FERROUS ALLOY Russian patent published in 2011 - IPC C23C8/36 

FIELD: metallurgy.

SUBSTANCE: procedure consists in placement of item into plasma chamber, in supply nitrogen or gas mixture into discharge interval between cathode and anode at low pressure of 0.01-1 Pa, also gas mixture consists of mixture of nitrogen and of at least one of following gases: argon, neon, helium or hydrogen, in applying voltage between cathode and anode with fine-structure mesh and in ignition arc or glow low voltage discharge with cold cathode creating plasma emitter of electrons in zone of fine structure mesh. Further, negative voltage of 0.1-1 kV is supplied between the anode and grounded walls of the plasma chamber, surface of the item is ion-cleaned from oxide films by means of supplying negative bias voltage 100-500 V relative to walls of the plasma chamber onto the item. The item is heated to working temperature facilitating diffusion of nitrogen atoms into volume of the item by growth of voltage between the anode and grounded walls of the plasma chamber and current of discharge between the anode and cathode. Atoms of nitrogen are diffused into volume of the item at values of negative bias voltage on the item 0-150 V relative to the grounded walls of the plasma chamber or at floating potential of the item.

EFFECT: raised surface hardness of item, elimination of deformation after treatment, increased fatigue point and wear resistance of processed item.

4 dwg, 1 ex