Magnetron sputtering is one of the most commonly used deposition techniques, which has received considerable attention in industrial applications. In particular, owing to its compatibility with ...conventional fabrication processes, it can produce and fabricate high-quality dense thin films of a wide range of materials. In the present study, nitrogen (N) was combined with pure vanadium in order to form binary nitride to improve its mechanical and tribological performance. To evaluate the influence of nitrogen on the structure of the as-deposited vanadium nitride (VN) coatings, the following techniques were used: XPS, XRD, SEM, AFM and optical profilometry. The residual stresses were determined by the curvature method using Stoney’s formula. The hardness and Young’s modulus were obtained by nanoindentation measurements. The friction behavior and wear characteristics of the films were evaluated by using a ball-on-disk tribometer. The obtained results showed that the N/V ratio increased with increasing the N
2
flow rate while the deposition rate decreased. The preferred orientation was changed from (200) to (111) as the N
2
flow rate increased with the presence of V–N and V–O binding energies as confirmed by XPS analysis. The nitrogen addition resulted in a columnar morphology and a fine structure with fine surface roughness. The VN thin film containing 49.5 at.% of nitrogen showed the best performance: highest mechanical properties (hardness = 25 GPa), lowest friction coefficient (
μ
= 0.37) and lowest wear rate (W
s
= 2.72 × 10
−5
mm
3
N
−1
m
−1
). A good correlation between the film microstructure, crystallite size, residual stress and mechanical and tribological properties was observed.
Chromium nitrides were deposited by RF reactive magnetron sputtering from a Cr target on high carbon steel substrates XC100 (1.17 wt% carbon) in a N2 and Ar gas mixture. In order to investigate the ...formation of chromium nitrides, carbide and carbonitride compounds were subjected to vacuum annealing treatment for 1 h at various temperatures ranging from 700 to 1000 °C. The samples were characterized by EDS, XPS, XRD, SEM, nanoindentation and tribometry. The results showed the emergence of Cr2N and CrN during the early stages of annealing and the appearance of chromium carbonitride phases only at 900 °C. The (111) preferred orientation of the fcc CrN phase was changed to (002) at 900 °C in parallel with the appearance of chromium carbides. Nanoindentation tests revealed a gradual increase of the Young's modulus from 198 to 264 GPa when increasing the annealing temperature, while the hardness showed a maximum value (H = 22.4 GPa) at 900 °C. The low friction coefficient of the CrCN coating against a 100Cr6 ball was approximately 0.42 at 900 °C. The enhancement of mechanical and tribological properties was attributed to the stronger bonding CrC at the CrN/XC100 interfaces as confirmed by XPS results.
•CrCN coatings were deposited on steel by RF reactive magnetron sputtering.•Microstructure of the coatings was strongly affected by the annealing treatment.•High temperature promotes the diffusion of carbon from substrate towards the film.•Thermal durability and high abrasive wear resistance with CrC and CrN bonds.
To purify water at low cost for our daily life, the effect of ceramic-based (mullite–cristobalite) and (mullite–zircon) powders doped with different amounts of magnesium oxide (MgO) (10 and 20 wt%) ...was studied. These compounds are made of a local raw material DD3 with addition of zirconia (ZrO
2
) to create an open porosity. The powders were prepared by the traditional mixing method with the help of an automated crushing. The effect of MgO doping on structural, morphological and photocatalytic properties of the material was studied by various analytical techniques such as X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, infrared, and UV–visible spectrometry. The results of XRD proved that there was a deformation in the crystal structure of the two types of ceramics after addition, which resulted in a shift of the spectra to the right, while SEM proved the presence of pores with a larger size as the proportion of MgO increases. The chemical composition of the basic components of the ceramic compounds as well as the additive was confirmed with EDS and IR spectra. The final results show that ceramics with added zirconia (DD3Z) and doped with 10% of MgO have a better photocatalytic efficiency than ceramics without zirconia. This important effect could be related to the higher rate of porosity, which provides a more active surface. The 10% MgO content showed a high photoactivity of 77.33% in only 15 min. The maximum hydrolysis rate obtained with Orange II was 92.95% after a period of 45 min with DD3Z/MgO powders.
To evaluate the role played by the substrates on the change and the actual difference of the studied samples on their structural, morphological, optical and photocatalytic properties, thin layers of ...zinc oxide grafted with magnesium were prepared with the same number of layers, doping ratio and experimental conditions with the use of two types of porous ceramic substrates and glassy. The XRD analysis detected the polycrystalline structure with wurtzite-type for all synthesized samples. The grain size was found to vary between 39 and 21 nm for DD3Z and 23 nm to 17 for glass. UV–visible absorbance data indicated that all MZO films absorb visible light at around 410 nm. In addition, a blue shift toward shorter wavelengths side was noted with increasing magnesium content up to 4 wt%, while the band gap showed an increasing trend achieving 3.07 eV for ceramics substrate. SEM analysis showed that the doping greatly affected the morphology of ZnO samples. Based on the results shown by the photocatalytic activities of orange II, the doping with magnesium gave a significant improvement to the samples with a ceramic substrate compared to the samples with a glass substrate. To reveal the mechanism of photolysis Hole/radical scavengers were used. It was found that the addition of Mg–ZnO networks increases the adsorption of hydroxyl ions on the surface and thus acts as a trap site leading to the reduction of hole/electron pair and thus increasing the activity and enhancing photodegradation.
In this work was prepared α-Al2O3 alloys from laboratory aluminum oxide powder that was milled for different periods of time and sintered at a temperature of 1450 °C. The difference between the ...prepared samples was studied using several experimental measurement techniques, including X-ray diffraction, scanning electron microscopy and measurement of physical and mechanical properties. Moreover, the effect of milling time on the formation and sintering of alpha-alumina, by milling the mixture at different times using high energy crushing technique was studied. An influence of milling time on density, open spaces and microstructure of the samples was analyzed. The obtained results showed that longer milling duration led to alloys with higher hardness (H) and modulus of elasticity (E). This improvement is due to lower porosity and corresponding higher density at high temperatures. A noticeable decrease in the size of the particles with the increase of the milling time led to an increase in the lattice parameter accompanied by a decrease in defects and ionic voids. The percentage of pores reached 0.04 % within 24 h of grinding after it was approximately 0.20 %, while the density reached 96 % after the same highest grinding time. Tests showed that the value of friction coefficient decreases, while it increases with the increase in the applied pressure force and this was confirmed by SEM images of the samples. the main factor to reduce friction is the increase in grinding time, regardless of the value of the applied load. The results showed that the Al2O3 alloy applied to it with a load of 2 N and milled for 24 h had a minimum value of 1.94 µm3 wear volumes and a wear rate of 1.33 (µm3∙N−1∙µm−1). The sample milled for 24 h showed the best result, characterized by the lowest wear size, specific wear rate and the highest hardness with extraordinary density of 96 %, which is important in the field of biomaterials applications.
Surfactants are widely used in many chemical industries and as primary components of cleaning detergents due to their specific characteristics, which in turn results in high pollution of domestic and ...industrial wastewaters by such substances. In this study, the mechanistic pathways of the adsorption of cationic benzyl-dimethyl-dodecyl ammonium bromide (BDDAB) and anionic sodium dodecyl sulfate (SDS) surfactants on kaolinite clay in water were investigated. The results showed that the adsorption of anionic surfactant (SDS) on kaolinite is better compared with cationic surfactant (BDDAB), wherein the ♦maximum adsorption capacity was found 161.4 μmol g
−1
and 234 μmol g
−1
for BDDAB and SDS, respectively. Adsorption kinetics were the best suited to pseudo-second-order model for both BDDAB and SDS with an adsorption rate constant of 0.028 g μmol
−1
min
−1
and 0.023 g μmol
−1
min
−1
, respectively. Meanwhile, the adsorption of BDDAB by kaolinite showed that the isotherm adsorption tended to follow the Langmuir-Freundlich and Freundlich isotherm models. However, the SDS adsorption isotherm obeyed only the Langmuir-Freundlich model.
The influence of milling time on the tribological behavior of a Co–Cr–Mo alloy designed for biomedical applications, synthesized via mechanical alloying is investigated. Elemental Co, Cr and Mo ...powders are milled using different milling times (2, 6, 12 and 18 h) in a high-energy ball mill. The resulting powders were subjected to cold uniaxial and hot isostatic pressing respectively, followed by sintering to obtain cylindrical samples, which were evaluated for their structural, mechanical and the wear behavior. Results showed that the grain and crystallite sizes of the powders decreased with increasing milling time, reaching low values of <10 μm and 32 μm respectively, at higher milling times. Furthermore, the wear rates and the coefficients of friction were lower, at higher milling times due to high densities (96%), and higher elasto-plastic resistance, as presented by the H/E and H3/E2 values of 0.026 and 0.0021 GPa, respectively. Increased milling time enables the refinement of grains and reduction in porosity in the Co–Cr–Mo alloy, which in turn increases the alloy's elasto-plastic resistance and enhances its wear resistance.
Implant-related follow up complications resulting from poor implant integration, delamination, chipping, mechanical instability, inflammation or graft-vs-host reaction may lead to low patient ...tolerance, prolonged care and sometimes leading to a second surgery. Hence, there is an urgent need for developing biomaterials which will help to overcome the above compatibility problems. Ti based alloys have been widely used for biomedical applications, due to their excellent properties, such as low modulus, high biocompatibility and high corrosion resistance. In order to further improve the physical, mechanical and tribological properties of these alloys, microstructural modification is often required. Hence, this study aims to develop and evaluate the structural and tribological behavior of Hot Isostatic Pressed (HIPed) and sintered Ti-6Al-7Nb samples containing niobium, which is less toxic and less expensive as compared to the usual alloying element, vanadium (Ti-6Al-4 V). The Ti-6Al-7Nb alloys were fabricated by using nanoparticle powders milled for different durations (2, 6, 12 and 18 h) to evaluate the effect of milling time on the morphological and structural properties. Friction and wear tests were carried out on the (HIPed) and finally sintered Ti-6Al-7Nb alloy samples, to evaluate their tribological properties under different applied loads (2, 8 and 16 N), with an alumina α-Al2O3 ball as a counter face using an oscillating tribometer. The physical characterization of the nanopowders formed using different milling times indicated that the particle and crystallite size continually decreased with increasing milling time, while the microstrain increased. It is observed that the friction coefficient and wear rate for the samples prepared by powders milled for 18 h and tested under 2 N were lowest with values of 0.25 and 1.51 × 10−2 μm3∙N-1 μm-1, respectively compared to other milled samples. This improvement in tribological properties is attributed to the grain refinement at high milling times. The antibacterial evaluation of the fabricated alloys showed an improvement in antibacterial performance of the samples milled at 18 h compared to the other milling times.
In order to create alloys with exceptional properties for orthopedic uses, this study focuses on the impact of zirconium (Zr) content on the structural, electrochemical, and tribological qualities of ...nanostructured Ti–25Nb-xZr x = 5, 10, 15, 20, 25, and 30 atomic (at.) % alloys. The structural evolution was investigated using XRD and SEM techniques. The mechanical characteristics of the produced alloys, including Vickers hardness and Young's modulus, were measured. In addition, the corrosion tests were performed using the OCP, EIS, and PD methods in Ringer's solution within the independent pH range at 37 °C. A ball-on-disc tribometer was used to investigate the tribological behavior of the alloys under various loads and wet conditions using the Ringer solution. It has been verified that Zr content (at. %) in the alloys had an impact on their morphologies, structural evolution, and mechanical characteristics. According to the morphological analysis, the particle and crystallite size decreases with increasing Zr content. Young's modulus and Vickers hardness show the same tendency. The EIS data demonstrated that a single passive film formed on the alloy surfaces, and the addition of Zr enhanced the corrosion resistance of the passive films. The polarization curves demonstrate that the alloys had low corrosion current densities and large passive areas without the passive films disintegrating. Likewise, the inclusion of Zr resulted in a reduction in the corrosion and passive current density values. All of these results suggested that the titanium alloys exhibit a more noble electrochemical activity caused by Zr. From the tribological perspective, it was found that the friction coefficient of the alloys reduced with increasing Zr content.
•HiPed Ti–25Nb-XZr alloy was prepared with varying Zr content.•The lattice parameter and micro strain decreased with increasing Zr.•Alloy with highest Zr content (30 wt%) showed the lowest friction and wear rate.•Mechanical properties resulting from the refinement of grain size and reduction in porosity.
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•Synthesis and characterization of a Schiff base, 4-(2-hydroxyanilino)pent-3-en-2-one.•The hydroxyl group within the Schiff base acts as a good radical scavenger.•The Synthesised ...Schiff base has the potential to be used in the pharmaceutical field.
Schiff bases are crucial intermediates in organic chemistry. They are used to introduce carbon–nitrogen double bonds in organic molecules. In this study, 4-(2-hydroxyanilino) pent-3-in-2-one (L) was synthesized from the reaction of 2,4-pentanedione and 2-aminophenol. The structure of L was confirmed through analytical and spectroscopic data. In addition, its thermal stability was examined using thermogravimetric and differential thermal analysis. In the gas phase, investigations of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) revealed an energy gap (ΔE) of 3.9304 eV. The antioxidant capacity of L was assessed using various techniques, including hydroxyl radical scavenging, scavenging of 2,2-diphenyl-1-picrylhydrazyl (DPPH), β-carotene bleaching, and scavenging of 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid (ABTS). The synthesized Schiff base displayed significant antioxidant activity, with a half-maximal inhibitory concentration (IC50) of 19.8 µg/mL in the DPPH assay, 0.14 µg/mL in the ABTS assay, and 59.6 μg/mL in the hydroxyl radical scavenging assay. The bioactivity of the 4-(2-hydroxyanilino) pent-3-in-2-one was confirmed by the DFT study, and the MEP analysis indicates the reactivity of nitrogen and oxygen atoms. Docking studies and wave function analyses were conducted to provide further insights into the compound’s potential applications in the pharmaceutical field.
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