Properties of stainless-steel surface after hollow cathode assisted plasma nitriding

Abstract

AISI 304 stainless steel was nitrided at different temperature in the plasma equipment using a new auxiliary device. The proposed hollow cathode auxiliary device improves the plasma density, thereby accelerating the nitriding process. The modified surface was characterized by x-ray diffraction, scanning and transmission electron microscopies, atomic force microscopy, surface microhardness testing. Electrochemical corrosion test was used to measure the localized corrosion resistance of the samples. Single S-phase layer without the CrN precipitation was obtained by hollow cathode plasma nitriding at 450 °C, which improved the microhardness, wear and corrosion resistance of the steel surface. Nitriding at higher temperature of 550 °C resulted in substitution of the S-phase towards layer composed from CrN and α-Fe phases, improving the microhardness but decreasing the corrosion resistance.

Scratch Response of Hollow Cathode Radiofrequency Plasma-Nitrided and Sintered 316L Austenitic Stainless Steel

“…In the SEM images in Figure 4, the precipitation of chromium nitride phases in the form of dark gray regions within the layer is not observed, contrasting with the findings in plasma-nitrided layers obtained at temperatures higher than 500 • C [35,41]. Furthermore, slip lines are observable within the nitrided layer, formed due to the plastic deformation that was induced during the plasma-nitriding treatment [11].…”

“…Therefore, the heating efficiency in HCD plasma nitriding can be raised compared to conventional plasma nitriding. This results in an effective treatment of austenitic stainless steels, promoting a uniform single S-phase layer without the CrN precipitation, enhanced hardness, and wear and corrosion resistance [31][32][33][34][39][40][41][42].…”

Solid Lubrication System and Its Plasma Surface Engineering: A Review

“…It has obvious advantages in energy saving and environmental protection [30][31][32]. There are various methods of chemical heat treatment, typically named after the infiltrated elements or compounds formed, such as nitriding [33][34][35], carburizing [36][37][38], nitrocarburizing [39], sulfurizing [40], oxidizing [41], among others.…”