saeid mersagh dezfuli

In the present study, Diamond-Like Carbon (DLC) coating was applied using two hydrocarbon precursors, methane (CH4) and acetylene (C2H2) through the PVD-IBD process. Raman spectroscopy and nano-indentation analyses were conducted to study the effect of hydrocarbon precursor on the structural and mechanical properties of the DLC coatings. Additionally, Field Emission Scanning Electron Microscopy (FESEM) and Atomic Force Microscopy (AFM) were employed to investigate the surface morphology and topography of the created coatings. The results from Raman analysis revealed a smaller ID/IG ratio and a larger FWHM for the DLC coating synthesized with acetylene hydrocarbon precursor. Cross-sectional FESEM images of the resulting coatings demonstrated a higher deposition rate of carbonaceous species when using the acetylene precursor. Further, AFM analysis showed that the surface roughness of the DLC coating produced with acetylene hydrocarbon precursor was lower than that obtained with methane. Finally, nano-indentation testing indicated that the DLC coating created using acetylene gas source (C2H2) exhibited higher hardness (H) and elastic modulus (E).

In this research, the diamond-like carbon coating was created by ion beam deposition with the aim of evaluating and increasing the corrosion resistance of 316L stainless steel in solution of simulated body fluid (SBF). Analyzes of the Raman Spectroscopy, field emission electron microscope (FESEM), atomic force (AFM) and electrochemical analyzes were used to characterize the structure and investigate the corrosion behavior of diamond-like carbon coating. The results of Raman analysis showed the formation of diamond-like carbon with a low ID/IG ratio. FESEM and AFM observations of the diamond-like carbon coating surface showed the formation of a continuous and crack-free coating with thickness of 500 nm and surface roughness of 9 nm on the surface of 316L stainless steel. The results of potentiodynamic polarization test showed a significant reduction in the corrosion current density (Icorr) of 316L steel by the diamond-like carbon coating. The results of electrochemical impedance test showed high load transfer resistance and increased corrosion resistance of 316L stainless steel by diamond-like carbon coating.

Carbon ion energy is a key factor in determining the amount of sp3 bonds in the structure of the amorphous carbon film and its like-diamond nature. In this study, the structural evolution of diamond-like carbon coating based on the mechanism of sp3 bond formation of amorphous carbon under the influence of the ion beam energy in the radio frequency ion-beam deposition process were investigated. For this purpose, the parameter of ion beam energy was 200, 300, and 400 eV ​​ for the deposition of DLC coatings. Raman and X-ray spectroscopy (XPS) analyzes were used to evaluate the structure and chemical composition of the coatings. Also, in order to determine the effect of ion beam energy on the surface roughness and thickness of the applied coatings, atomic force microscope (AFM) and field emission scanning electron microscope (FESEM) were used. Hardness and elastic modulus were measured by nanohardness test. According to the results of Raman analysis, the lowest value of ID/IG ratio was obtained in ion beam energy of 300 eV, which was equal to 0.66. The results of XPS analysis showed the lowest amount of sp2 bonds in the diamond-like carbon film at ion beam energy of 300 eV. Also, results of AFM analysis showed at ion beam energy of 300 eV, the surface roughness of diamond-like carbon coating has the lowest value. Due to the highest amount of sp3 bonds in the ion beam energy of 300 eV, the diamond-like carbon coating had the highest hardness and was equal to 10.6 GPa.

The substrate temperature plays an important role in the mobility of carbon species as well as the formation and growth mechanism of the amorphous carbon layers with diamond-like characteristics. The amorphous carbon structure can be transformed into the diamond- and graphite-like structure under the effect of substrate temperature. Given that, this study aimed to investigate the structural evolution of the diamond-like carbon coating followed by changing the substrate temperature through the radio frequency direct ion beam deposition. In this regard, the substrate temperature values were obtained as 80, 110, and 140 °C for the deposition of DLC coatings. Raman and X-Ray Spectroscopy (XPS) analyzes were done to evaluate the structure and chemical composition of the coatings. To further investigate the thickness and roughness of the applied coatings, Atomic Force Microscopy (AFM) and Field Emission Scanning Electron Microscopy (FESEM) were used. According to the results, the lowest roughness value of the diamond-like carbon coating surface was obtained at the substrate temperature of 110 °C. In addition, the lowest value of ID/IG and the highest amount of sp3 bonding were obtained at the same substrate temperature.

This study, investigates the effect of bias voltage on structural changes of diamond-like carbon thin film created by ion beam deposition is investigated. For this purpose, the bias voltage in the values of 0 V, -50 V, -100 V and -150 V on the AA5083 aluminum alloy was considered. Raman spectroscopy was used to evaluate structural. Influence of the bias voltage on the thickness and roughness of coatings by atomic force microscope (AFM) and field emission scanning electron microscope (FESEM) were investigates. Hardness and elastic modulus were measured by nanoindentation test. The results of Raman analysis showed the highest amount of sp3 bonds in the diamond-like carbon thin film at bias voltage of -50 Vs. results of AFM showed the lowest of surface roughness (10 nm) at bias voltage of -50 Vs. The hardness of diamond-like carbon thin film was 14.1 GPa at the bias voltage of -50 Vs.

In this study, the effect of yttria and benzotriazole doping on corrosion behavior and activation of self-healing mechanism in Alumina-based nanostructured coatings was investigated. Single-component Alumina, double-component Alumina-Ytteria, and triple-component Alumina-Ytteria-benzotriazole ceramic-based coatings have been ‎layer-deposited over St52 steel surface by the sol-gel process in order to improve the abrasion and corrosion behaviour of this steel. Afterwards, phase analysis, morphology, and topography of these coatings have ‎been carried ‎out respectively by Grazing Incidence X-ray Diffraction (GIXRD), Field Emission Scanning ‎‎Electron Microscopy (FE-SEM), and Atomic Force Microscopy (AFM).‎ Moreover, in order to investigate ‎elemental distribution in layer-deposited coatings, Energy ‎Dispersive Spectroscopy (EDS) ‎was performed.‎ Also, the corrosion behaviour of under-investigation coatings ‎and substrate were studied using electrochemical impedance spectroscopy and potentiodynamic ‎polarization for 1, 48, and 96 hours of immersion in 3.5wt%NaCl solution. GIXRD results revealed the ‎amorphous nature of the coatings and the absence of formation of ‎crystalline structure. AFM and FE-SEM ‎observations revealed intactness of double-component Alumina-Ytteria and Alumina-Ytteria-benzotriazole ‎coatings in comparison with single component Aluminacoating.