NITRATION OF MACHINE PARTS WITH PRODUCTION OF NANOSTRUCTURED SURFACE PLY AND PLY COMPOSITION Russian patent published in 2014 - IPC C23C8/36 B82Y30/00 

FIELD: process engineering.

SUBSTANCE: invention relates to metallurgy. Parts are processed by quenching at 920-940°C, subjected to negative hardening with heating to 600-650°C for 2-10 hours and removal of decarbonised ply. Then, ion-plasma nitration is performed at 500-570°C, cathode voltage of 300-320 V, and current density of 0.20-0.23 mA/cm². Ammonia with dissociation of 0-80% is used as a gas medium. Ammonia flow rate makes up to 20 dm³/h. Pressure in the chamber at cathode spraying makes 1.3-1.35 Pa and, at saturation, 5-8 GPa. This nitration is performed at cyclic temperature and ammonia dissociation variation. Note here that at the first half of described cycle temperature makes 570°C at maximum nitrogen potential. During second half, temperature decreases to 500°C while nitrogen potential is decreased owing to increase in ammonia dissociation to 40-80%. Note also that the number of said cycles should make at least 10. Nitrated part has surface ply containing diffusion ply with α-phase with nanosized incoherent alloying element nitrides that makes soft matrix. Besides, it has surface ply with hard inclusions composed by nanoparticles of ε-phase iron nitrides formed by local phase recrystallisation of iron nitride lattices. This results from cyclic temperature and ammonia dissociation variation.

EFFECT: higher wear resistance, longer life of kinetic friction parts made from above described material.

2 cl, 1 tbl, 2 dwg