Affiliation:
1. School of Engineering and Sustainable Development, Faculty of Computing, Engineering and Media, De Montfort University, Leicester LE1 9BH, UK
Abstract
Nitriding has long been used to engineer the surfaces of engineering steels to improve their surface and subsurface properties. The role of the surface compound layer (γ′-Fe4N and/or ε-Fe2-3N) in improving the tribological and corrosion-resistant properties of nitrided steels has been established. However, there have been very few studies on the response of the compound layer to tribocorrosion in corrosive environments. In this work, the tribocorrosion behavior of a 5 μm thick γ′-Fe4N nitride layer produced on mild steel (MS) by plasma nitriding has been studied in a NaCl-containing solution under various electrochemical conditions. The results show that at a cathodic potential of −700 mV (saturated calomel electrode, SCE), where mechanical wear is predominant, the total material removal (TMR) from the γ′-Fe4N layer is 37% smaller than that from the untreated MS, and at open circuit potential, TMR from the layer is 34% smaller than that from the untreated MS, while at an anodic potential of −200 (SCE), the γ′-Fe4N layer can reduce TMR from mild steel by 87%. The beneficial effect of the γ′-Fe4N nitride layer in improving the tribocorrosion behavior of mild steel is derived from its high hardness and good corrosion resistance in the test solution and its ability to resist both mechanical wear and corrosion and to reduce wear–corrosion synergism.
Subject
Surfaces, Coatings and Films,Mechanical Engineering
Reference39 articles.
1. Technological importance of plasma-induced nitrided and carburized layers on steel;Staines;Thin Solid Films,1981
2. Controlled nitriding;Spies;Met. Sci. Heat Treat.,2004
3. Lightfoot, B.J., and Jack, D.H. (1977). Heat Treatment ’73, American Society for Metals. Republished in the Source Book on Nitriding.
4. Mittemeijer, E.J., and Somers, A.L. (2015). Thermochemical Surface Engineering of Steels, Elsevier Woodhead Publishing.
5. Structure and properties of plasma-nitrided stainless steel;Menthe;Surf. Coat. Technol.,1995