جستجوی مقالات مرتبط با کلیدواژه "nanostructure coating" در نشریات گروه "مواد و متالورژی"

In this paper, nanostructured CrAlN coatings were deposited onto steel substrates using an industrial cathodic arc physical vapor deposition (Arc-PVD) technique. Field emission scanning electron microscopy (FESEM) was employed to evaluate the microstructure and the phase analysis was carried out using Energy Dispersive Spectroscopy (EDS) and X-ray diffraction (XRD) methods. The XRD patterns were used to determine the crystallographic texture of the coatings and the results showed (222) as the dominant texture. Moreover, it was found that all coatings had nanocrystalline structure with crystallite sizes between 8-18 nm. CrN was found to be the dominant phase in the XRD patterns; addition of aluminum produced CrAlN, leading to shifts of the diffraction peaks. Cr2N and AlN phases were identified by the XRD pattern which can be attributed to the decrease of the nitrogen pressure down below a critical value and the increase in the evaporation of aluminium, respectively. The change in the Al content of the coating and the subsequent displacement of the diffraction lines caused a challenge in the phase identification procedure. Therefore, identifying the existing phases in the coating was not feasible merely by the EXPERT software since CrAlN is not defined in its database; the crystal phase data of the nitride coatings must be used for accurate phase identification.

Nanostructured titanium oxide coating due to the optical properties, resistance to oxidation, corrosion, and erosion has become highly regarded. There are different ways for applying nanostructure coating such as CVD, PVD, sol - gel and so on. Among of these methods, the sol - gel method was used more application, due to the ease of having such benefits as efficiency, homogeneity and uniformity of the chemical composition of the coating. So, in this paper, the intermediate coating, adhesive and porous nanostructured titanium oxide, as maintenance reserves cerium inhibitor, applied by sol - gel method on aluminum 2024, after that a layer of homogeneous, uniform and compact titanium oxide applied on the middle layer, then the structural properties, morphology and coating composition were investigated by XRD, FESEM and AFM and corrosion properties of the coatings in 3, 5% NaCl solution was measured by electrochemical techniques such as polarization and impedance measured. The results showed homogeneity, uniformity and free crack coating and also improving the corrosion resistance of Al 2024 from 36 to 2449 (KΩcm2), about 68 times. These effects can be due to self-healing mechanism of nano cerium inhibitors by releasing and producing cerium hydroxide and finally prevent cracks propagation.