Plasma electrolytic surface carburizing and hardening of pure iron

In this study, surface carburizing of pure iron was investigated in aqueous solution, which consists of water, glycerin, and NH4Cl, for a very short period of time. The formation of hard carbon-rich layer on the surface of pure iron was confirmed by XRD analysis. SEM study combined with EDS showed the presence of carbon in the coated layer. Moreover, RF-Glow Discharge Optical Emission Spectrometry (RFGDOES) presents only carbon diffusion into the base material. Metallographic and SEM studies revealed that a uniform and compact carbon-rich layer was firmly sticking to the surface of the pure iron, and there was no crack observed between a carburized layer and a substrate. The average thicknesses of carbon-saturated layers were changing from 12 μm for 10 s to 78 μm for 60 min. The hardness of the carbon-rich layer on the substrate was 850 HV, while the hardness of the substrate was 150 HV.