Kara, Levent; Asl, Hojjat Gahramanzade; Karadayi, Özcan

TiN, TiAlN, CrAlN and TiAlN/TiSiN films were deposited on AISI H13 hot work steel substrate by cathodic arc evaporation method. Each coating was optimized in laboratory conditions and the highest hardness and wear resistance coatings were taken into consideration for this study. Morphological properties, chemical compositions, crystallographic structure, nano hardness and adhesion strength of coatings were analyzed with SEM, AFM, EDS, XRD, nano indentation and scratch resistance tester. Wear experiments were performed using ball-on-disk tribometer against Al2O3 ball of 6mm diameter and wear volume of coatings were measured using optical profilometer. Wear experimental results revealed that all coated samples showed higher wear resistance and hardness than uncoated AISI H13 steel substrate. The highest wear and scratch resistances as well as nano hardness were attained for CrAlN coating. TiAlN coating has the lowest scratch resistance and wear resistance. Adhesive wear mechanism was the dominant wear mechanism for CrAlN coatings which is the highest wear resistant coating. Abrasive wear mechanism was the dominant wear mechanism for TiAlN coatings which is the lowest wear resistant coating.

Çomakli, O.; Yetim, A.F.; Karaca, B.; Çelik, A.

The 31CrMoV9 steels were plasma nitrided under different gas mixture ratios to investigate an influence of nitrogen amount on wear behavior. The structure, mechanical and tribological behavior of untreated and nitrided 31CrMoV9 steels were analyzed with X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), microhardness device, 3D profilometer and pin-on-disk wear tester. The analysis outcomes displayed that the compound layer consists of nitride phases (Fe2N, Fe3N, Fe4N and CrN). Additionally, the thickness of the compound layers, surface hardness and roughness increased with increasing nitrogen amount in the gas mixture. The highest friction coefficient value was obtained at nitrogen amount of 50%, but the lowest value was seen at nitrogen amount of 6%. It was observed that wear resistance of 31CrMoV9 steel improved after plasma nitriding, and the best wear resistance was also obtained from plasma nitrided sample at the gas mixture of 94% H2+6% N2.

Aslan, M.; Çomakli, O.; Yazici, M.; Yetim, A.F.; Bayrak, Ö.; Çelik, A.

The present study was focussed on investigating the corrosion properties of plasma-oxidized and -nitrided CoCrMo alloys under different conditions. The structural properties of untreated and treated samples were examined by using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Corrosion behavior of samples was mainly investigated by potentiodynamic polarization and electrochemical impedance spectroscopy in simulated body fluid solution. The results showed that corrosion resistance of the oxidized layers was better than that of the nitrided ones. The corrosion resistance of the alloys increased as the plasma oxidation process temperature and time increased. However, the corrosion resistance of the alloys reduced with increase in the process temperature and time after plasma nitriding process.