Oxi-nitriding of alloyed steels with forming of nano-scaled oxide film

摘要

Thermo-chemical treatment of chromium corrosion resistant steels in 'separated' atmospheres of ammonia and air is investigated consisting in surface oxidising and subsequent nitriding. As the result internal nitriding zone is formed under the nano-scaled oxide layer consisting of chromium nitrides dispersed in the ferrite matrix. Prolonged nitriding leads to formation of powder ferrous nitride layer over the oxidised surface. Such composite coating shows the increase of wear resistance comparing with the classical nitriding: in 4-4.5 times in conditions of sliding friction, in 2-2.2 times in conditions of abrasive and hydro-abrasive wear.