METHOD OF INTERNAL CYLINDRICAL SURFACE PLASMA STRENGTHENING Russian patent published in 2018 - IPC C23C16/34 C23C16/513 

FIELD: technological processes; chemistry.

SUBSTANCE: invention can be used for the chemical-thermal treatment of the inner cylindrical surface of structural materials and products of low- and high-alloy steels, titanium and titanium alloys. Article is placed in a vacuum chamber. Argon is introduced into the vacuum chamber and the surface is pretreated with a pulse-periodic anomalous glow discharge, after which the product is heated to a temperature above 150 °C by means of an additional heating system. Carry out working gas puffing to a pressure of 0.5–5.0 Torr. Use a mixture of hydrogen and nitrogen or a mixture of hydrogen, nitrogen and argon for steel, and a mixture of argon and nitrogen or a mixture of helium and nitrogen for titanium and its alloys. Nitridizing is carried out in the plasma of a pulse-periodic anomalous glow discharge with a hollow cathode with heating of the surface of the article from steel to 400–650 °C, and articles made of titanium and its alloy up to 400–900 °C by means of an additional heating system. Then, nitrogen is introduced into the vacuum chamber and the article is cooled to a temperature of 25 °C under a nitrogen atmosphere at a high pressure of 800 Torr.

EFFECT: method provides an increase in hardness and corrosion resistance of parts with an internal cylindrical surface with a diameter of 3 mm.

1 cl, 3 ex, 5 dwg