Surface Modification of Low-Carbon Steels by Plasma Electrolytic Nitrocarburising

This study investigates the effect of the plasma electrolytic nitrocarburising conditions and electrolyte composition (NH 4 Cl, NH 4 NO 3 and glycerol) on steel structure and properties. The cross-sectional microstructure, composition and phase constituents of a modified layer are characterized. The thickness of each layer is determined by carbon and nitrogen diffusion, anode dissolution, and oxidation that occur simultaneously. These processes are affected by the concentration of electrolyte components. The aqueous solution containing NH 4 NO 3 , NH 4 Cl and glycerol enables to obtain the modified layer with the thickness of 0.20 mm and hardness of 930 HV, the decrease in the surface roughness from 1.01 to 0.15 µm, the corrosion rate by a factor of 4.4 and the weight loss after lubricate wear testing by a factor of 14.