In this investigation, a systematic characterization of the diffusion coatings was carried out. These coatings, developed by different nitrocarburizing processes, namely salt-bath, gas and plasma nitrocarburizing, were conducted on various steel substrates. The tested substrates were St 52-3, Ck 45, 42 CrMo 4, 30 CrNiMo 8 and X 20 Cr 13. The thickness of compound layers and their porosity were measured using optical microscopy. The structure of compound layers was characterised using an X-ray diffractometer and their surface roughness by a stylus profilometer. The surface hardness measurements and hardness profiles were carried out according to the Vickers principle.

Diffusion coatings have been used increasingly to modify surface properties of various machine components for several applications. In general, these coatings are used to improve the wear behaviour. Frequently, it is desirable that the corrosion behaviour will be improved at the same time.In this investigation, the corrosion behaviour of various diffusion coating substrate-combinations has been studied. The coatings developed by three different nitrocarburizing processes, namely salt-bath, gas and plasma nitrocarburizing, were conducted on five various steel substrates. These substrates were St 52-3, Ck 45, 42 CrMo 4, 30 CrNiMo 8 and X 20 Cr 13. The thickness of the compound layers and their porosity were measured using optical microscopy. The structure of the compound layers was characterized using an X-ray diffractometer and their surface roughness by a stylus profilometer. The corrosion test was carried out using a salt-water spray test. The predominant corrosion mechanisms have been evaluated using scanning electron microscopy.It was found that the employed nitrocarburizing processes have improved the corrosion resistance of all tested coating-substrate-combinations comparing with that of the base materials. In general, the corrosion resistance increases with an increase of the compound layer's thickness and after an oxidation process. The best coating-substrate-combinations to improve the corrosion behaviour were salt-bath nitrocarburized tempering steels, whereas the thin layers of the plasma nitrocarburized specimens were the worst.

Diffusion coatings have been used increasingly to improve surface properties of several machine components for tribological applications.In this investigation, the abrasive wear of various diffusion coatings has been studied. These coatings developed by three different nitrocarburizing processes, namely salt-bath, gas and plasma nitrocarburizing, were conducted on five various steel substrates. The substrates were St 52-3, Ck 45, 42 CrMo 4, 30 CrNiMo 8 and X 20 Cr 13. The thickness of the compound layers and their porosity were measured using optical microscopy. The structure of compound layers was characterized using an X-ray diffractometer, and their surface roughness by a stylus profilometer. The surface hardness measurements and the hardness profile were made according to the Vickers principle. The abrasion test was carried out using a pin-on-table machine. The predominant wear mechanisms have been evaluated using scanning electron microscopy.It was found that the employed nitrocarburizing processes have improved the abrasive wear resistance of all tested coating-substrate-combinations. In general, the abrasive wear rate decreases with an increase in the hardness of the compound layer as well as its thickness. The best coating substrate-combinations to improve abrasion resistance were salt-bath and gas nitrocarburized specimens of the substrate X 20 Cr 13. Plasma nitrocarburized specimens of the substrate St 52-3 and Ck 45 were the worst.