METHOD OF CYCLIC GAS NITRATION OF STRUCTURAL ALLOY STEEL PARTS Russian patent published in 2017 - IPC C23C28/04 C23C8/26 C23C8/34 

FIELD: metallurgy.

SUBSTANCE: method of cyclic gas nitration of structural alloy steel parts includes part heating in the furnace up to the temperature of 540-650 °C, isothermal holding at the heating temperature, during which the saturating atmosphere replacement is performed cyclically in two stages in each cycle, and subsequent cooling together with the furnace in the ammonia-base atmosphere. The nanoscale copper film is prelimenary applied to the part surface, and the mentioned heating is conducted in the ammonia and carbon dioxide atmosphere at a volume ratio of these components 1:1. The first cycle stage of isothermal holding is carried out in saturating ammonia atmosphere in a mixture with water vapour at a ratio of volumes of mentioned components 1:1 and obtaining the copper oxide film on the part surface. The second step of the mentioned cycle is carried out in saturating ammonia atmosphere in the mixture with carbon dioxide at the ratio of mentioned gas volumes 1:1, and with the copper oxide recovery up to forming the pure copper on the part surface. In the invention particular case, the thickness of the applied nanoscale copper film is within the range of 150-200 nm.

EFFECT: increase of metal ceramics solid area thickness up to a specified value in the diffusion nitrided layer, obtained at the parts surface from structural alloyed steel without the nitriding process duration increase and without reducing its hardness.

2 cl, 1 tbl, 5 ex