جستجوی مقالات مرتبط با کلیدواژه « magnetron sputtering » در نشریات گروه « مواد و متالورژی »

In this study, Ta, TaC and TaSiC coatings have been deposited by a non-reactive magnetron sputtering method, and their structural, microstructural, mechanical, and corrosion properties have been investigated. XRD results revealed the presence of α-Ta and TaC0.6 phase structures in the Ta and TaC coatings, respectively. However, the TaSiC coating showed a quasi-amorphous structure. Additionally, the Ta coating showed a columnar microstructure with rough topography and tensile residual stress, while the addition of carbon and silicon resulted in the compactness and smoothness and domination compressive residual stress in the TaC and TaSiC coatings. Nanoindentation results showed that the addition of carbon to the Ta coating increased the hardness by four times, however the addition of silicon to the TaC coating had an adverse effect on the hardness of the coating. The corrosion studies revealed that the coatings have a cathodic nature with respect to the ST37 substrate, making the samples susceptible to galvanic corrosion. Furthermore, the addition of carbon and silicon was found to improve the corrosion resistance of the coatings by increasing the coating compactness and decreasing the density of open porosities.

In the present work, two- component heterostructure of ZnOnanorods array (ZnO NRs) and CuO nanostructure has been grown. Well-aligned ZnO NRs have been synthesized using seed layer by low temperature wet chemical method. Then, CuOthin film has been form by thermal oxidation ofCu thin film deposited by magnetron sputtering on ZnO NRs to increase and expand optical absorption to visible region. The structure, morphology and chemical, optical, photocatalytic properties of ZnO NRs/CuOheterostructures have been studied by, X-ray diffractometry (XRD), field emission- scanning electron microscope/ energy dispersive X-ray spectroscopy (FE-SEM /EDX), UV-Vis- near IR optical absorption spectroscopy, and current – voltage measurement, respectively.Thermal oxidation of Cu thin film on ZnO NRs in the temperature range 200- 600 °C Cause ZnO NRs/CuO TF heterostructure to form. The ZnO NRs/CuOheterostructures increase and expand optical absorbtion to visible range in comparision to bare ZnO NRs.Photocatalytic activity of ZnO NRs/CuOheterostructure was investigated through Rhodamine B (RhB) photodegrdation under UV- Vis irradiation.Photocatalytic efficiency of ZnO NRs/CuOheterostructure is considerably increased in comparison to bare ZnO NRs

In this study, due to the poor corrosion resistance of Mg alloys in aquatic environments, TiO2 ceramic coating applied by the magnetron sputtering technique to enhance the corrosion resistance and biocompatibility of AZ91D alloy. The Microstructural studies by field emission scanning electron microscopy (FESEM) and X-Ray diffraction (XRD) analysis showed that the coating formed uniformly with semi spherical morphology containing TiO2, Mg2TiO4 and MgTi2O5 spinels, so that above of the substrate was Ti diffiusion affected. The polarization corrosion test in simulated body fluid (SBF) solution showed that applying the coating by reducing the corrosion current by about 100 times improves the corrosion resistance of the magnesium substrate so that MTT results show that density and number of cells on the coated sample is higher than substrate without coating due to cell joint stronger. The viability of MG67 cells on the samples increased from 77% in the substrate to 89% in the coated sample.

Nowadays, suitable protective properties of tantalum nitride coatings, such as hardness, abrasion resistance and high corrosion resistance lead to increasing its application in medical engineering and improving the biological behavior of titanium and its alloys. In this research, nanostructured tantalum nitride coating was applied on the NiTi alloy by magnetron sputtering method. Then, the phase, structural and morphological properties of coating were investigated by using XPS, FESEM, AFM, respectively, as well as the nanomechanical properties of the coating were evaluated by using Nano-scanning and nano-scratch methods in different loads.
The results indicate that applying the uniform, homogeneous and crack free tantalum nitride coating with a thickness of 1050 nm. The hardness and elastic modulus of coating is 12.6 and 87.4 GPa under the applied force of 1000 μm and the penetration depth of 91 nm, respectively, which resulted in enhancing the hardness of NiTi alloy surface, about 34%. The coefficient of friction is 0.28 and the dominated wear mechanism of nanostructured tantalum nitride coating is abrasive wear with shearing mechanism.

Although tantalum nitride coatings have recently been attracted researchers’ attentions due to their high hardness and corrosion resistance, the fracture toughness and deformation plasticity of thin tantalum nitride film has not been well investigated yet. In this research, for the first time, the fracture toughness, strain rate sensitivity and plasticity of sputter deposited tantalum nitride thin films have been evaluated using nano indentation technique and SEM micrographs. It was shown that the fracture toughness was increases from 0.6 to 7.8 MPa√m with increasing the nitrogen in sputtering chamber. This increase was attributed to the structural evolution from a hexagonal γ-Ta2N phase to the hexagonal ε-TaN and face centered cubic δ-TaN phases, determined by X-Ray Diffraction analysis. The plasticity of the TaN films evaluations indicated that the ratio of plastic work to total work was increased from 50% to 57% and 80%with phase variation from γ-Ta2N to ε-TaN and δ-TaN, respectively.

In this study, tantalum (Ta) thin film was deposited on Si(100) and 316L stainless steel (SS) substrates by DC magnetron sputtering. The structural properties of Ta film were investigated by X-ray diffraction analysis. In addition, the scanning and transmission electron microscopies as well as atomic force microscopy were used to study the cross-section and the morphology of the coating. The corrosion behavior of the bare and Ta-coated 316L SS was evaluated by potentiodynamic polarization test. The electrochemical impedance spectroscopy was employed to study the corrosion mechanisms. The results revealed that the structure of Ta coating on either Si and SS substrates is a mixture of αβ phases, while pre-deposition of a thin tantalum nitride seed layer causes to the deposition of pure α-Ta and decrease the sheet resistance from 90 µΩ.cm to 15 µΩ.cm. Microscopic evaluations shows that the Ta coating is compact, homogeneous and defect-free, exhibiting a columnar structure with a surface roughness of less than 6 nm. Furthermore, the corrosion studies show that the Ta coating perform as a physical barrier between corrosive electrolyte and substrate and, in this way, provide a protective efficiency of more than 70%. In this regard, the diffusion of corrosive electrolyte toward the substrates through open porosities was found to be the corrosion mechanism of the Ta coating and the porosity index of the coating was calculated to be about 6%.

In current research, single HA, single TiO2, and double layer HA/TiO2 coatings was applied on Ti-6Al-4V substrate by AC/DC magnetron sputtering method with obtained optimum parameters. The parameters were: power 175 W to coat single HA layer, optimum Ar/O2 ratio of 30/70 for coating TiO2 thin film, both which applied for HA/TiO2 multilayer coating sample. In addition, the effect of heat treatment temperature on hydroxyapatite layer growth was investigated. Phase formation, morphology, and roughness of coatings’ surface were investigated by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Atomic Force Microscope (AFM), respectively. Also, the effect of exposing samples to simulated body fluid (SBF) was studied. SEM images confirmed the formation of calcium phosphate precipitations on the surface of coatings. The XRD patterns and EDS analysis results showed the precipitations formed on surface of coatings were calcium phosphate phases. The corrosion test showed that the corrosion resistance of heat-treated HA/TiO2 multilayer coating was improved, 0.041 A.cm-2 in comparison with 0.015, 0.007, and 0.003 for single HA, untreated multilayer, heat-treated multilayer at 500ºC and 800ºC, respectively. SEM micrographs showed that at same periods of soaking samples into SBF, more precipitation formed on HA/TiO2 coating in than HA coating which indicates the improvement of bioactivity of Ti implants with applying the HA coatings, also showing 300 nm thick layers of HA and TiO2 on the alloy surface. AFM results showed that surface roughness of uncoated Ti alloy was improved by applying coatings of single HA, single TiO2, and multilayer HA/TiO2. The results of AFM also demonstrates that the single HA and single TiO2 coatings had similar surface roughness ( 64 Å) while untreated multilayer coating had an improved roughness of 73.5Å. The surface roughness was increased drastically for heat-treated multilayer sample at 800ºC due to positive effect of heat treatment on hydroxyapatite coating’s surface properties.

The purpose of this research is investigation of two fine grained stainless steel coatings produced by two physical vapor deposition methods, i.e. magnetron sputtering and cathodic arc evaporation, on a carbon steel substrate. The coatings were compared according to their structure, hardness and adhesion. In order to evaporate the target atoms, high power (3300 w) was applied on the cathode surface in cathodic arc evaporation method and argon pressure (105 Pa) was used in magnetron sputtering method. For comparison of these coatings, the same substrate temperature (300 ± 50 oC) and bias voltage (250± 50 V) and also similar deposition time (50 min) were used. XRD, EDS, SEM and FE-SEM methods were used for characterization of the coatings. Nano-indention and Vickers indenter tests were also carried out for evolving the hardness and adhesion of the coatings. The EDS analysis results showed that the magnetron sputtered coating had a composition similar to the target material, whereas the cathodic arc evaporation coating had a different composition. Also, the nano-indention test showed that the magnetron sputtered coating hardness increased up to about 890 Vickers, which is much higher than that of the cathodic arc coating (about 260 Vickers) and bulk 304 stainless steel (220 Vickers), due to its nano-crystalline structure. However, the sputtered coating adhesion was evaluated weaker than that of the cathodic arc coating, because of the existence of more cracks at the edges and also local spalling of the coating.

In this study the structure of Cu-Ni3Al-MoS2 composite coating using physical vapor deposition have been investigated. It is expected, the use of this coating for operation in dry conditions and different temperatures, provides good abrasion resistance and lead to increase the life time of components while maintaining the economic efficiency. Because of the presence of the employed elements, Cu-Ni3Al-MoS2 coating has a good lubrication and conductivity properties with hard structure. This coating is used in aviation industries in cases, where surfaces slip to each other. For this purpose Target tablets containing Ni3Al-wt.30% MoS2 with a copper substrate were prepared using magnetron dispersion of composite coating Cu-Ni3Al-MoS2 structure was created on 4340 steel substrate. Coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy depressive spectroscopy (EDS) and roughness measurement test (RT). The hard cover was calculated, by the Vickers microhardness measurement of Cu-Ni3Al-MoS2 about 380 HV over 25 g load. During the study, it was demonstrated that this coating has a good adhesion and morphology with substrate.

Vanadium oxide (VOx) thin films prepared in a direct current magnetron sputtering system. In order to get different vanadium oxide phases the films anneled under different temperature and atmospheres. At first vanadium oxide (VOx) thin films annealed at two temperatures of 450 and 500oC. Mixed structure of VO2 and V2O5 phases formed in both samples while VO2 phase was the main phase at 450oC and changed to V2O5 phase at annealing temperature of 500oC. In the next step vanadium oxide (VOx) thin films prepared under two sputtering pressures of 2 and 5 torrand then annealed at 450oC. The results revealed that sputtering pressure doesnot have a big impact on crystal structure of vanadium oxide thin films. However، vanadion oxide thin films that prepared at lower sputtering pressure shows smaller grain size and higher hardness and Young،s modulus. Then the effects of annealing atmosphere (air and oxygen atmospheres) on microstructure and properties of vanadium oxide thin films that prepared at sputtering pressure of 2 torr and anneled at 450oC was investigated. It was shown that annealing atmospheredoesnot affect crystal structure of the films while mixed structure of VO2 and V2O5 in both samples. There is a possibility that some phases have been formd in amorphous. Vanadium oxide (VOx) thin film which anneled under oxygen، showed smaller grain size and better mechanical properties. The results of current study showed that deposition and annealing conditions have a big impact on microstructure and mechanical properties of vanadium oxide (VOx) thin film.

Tungsten, tungsten nitride and tungsten oxide coatings were prepared in a planar magnetron sputtering system at different sputtering conditions. Tungsten films prepared at different sputtering pressures and resulted to a mixture of WO3 and β-W phases while the peak intensity of WO3 phase was the lowest at an optimum sputtering pressure. Tungsten nitride and tungsten oxide coatings were deposited at different partial pressures of reactive gases at constant sputtering pressures. Total pressure was fixed at 9×10-3 torr while P(N2/Ar) ranged between 0.4-5 for nitride coatings and 0.25-2.5 for oxide coatings. At low reactive gas partial pressures, nitride and oxide phases were formed. However, by increasing the gas flow rate, coatings lost their long range order and amorphous like structure was formed. The surface roughness of the films prepared at higher partial pressure of reactive gas was higher. Lower adatoms mobility at higher reactive gas pressures leads to the formation of films with amorphous-like structure and higher roughness. The results showed that oxide films are more sensitive to the partial pressure of reactive gas compared to that of nitride films.

In this resead solar mirrors were made from silver nano layers on a white glass substrate. In this regard the DC magnetron sputtering was used for diposition of silver. ITO layers were used to enhance the adhesion of the main layer. The layers were characterized by spectrophotometery, RBS and XRD. It was observed that IR reflection was enhanced with the increase in Ag thickness. However increase in ITO layer and substrate temperature, and decrease in grain size, decreased the IR reflection.