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

Authors: Larisa Petrova; Larisa Shestopalova

Addresses: Department of Technology of Construction Materials, Moscow Automobile and Road State Technical University (MADI), Leningradskiy, 64, 125319 Moscow, Russian Federation ' Department of Technology of Construction Materials, Moscow Automobile and Road State Technical University (MADI), Leningradskiy, 64, 125319 Moscow, Russian Federation

Abstract: 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.

Keywords: oxi-nitriding; chromium steels; nano-scaled oxide film; internal nitriding zone; modified layer; microhardness; wear resistance; corrosion resistance; corrosion resistant steels; surface oxidising; ammonia; air; chromium nitrides; ferrite matrix; composite coatings; sliding friction; abrasive wear; hydro-abrasive wear.

DOI: 10.1504/IJMMP.2014.061057

International Journal of Microstructure and Materials Properties, 2014 Vol.9 No.1, pp.25 - 37

Available online: 24 May 2014 *

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