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.
The scope of this work is to propose a methodology allowing the determination of the single-crystal elasticity constants of a phase included in a multiphase thin film taking into account its ...microstructure (crystallographic and morphological texture, porosity and multiphase aspect). The methodology is based on the use of a macro-mechanical test, the impulse excitation technique, a micro-mechanical test, X-ray diffraction and the Kröner-Eshelby scale transition model. As a supporting example, it was applied to determine the single-crystal elasticity constants of the Wβ tungsten metastable phase embedded in a two phases (α+β) tungsten thin film deposited on a steel substrate by DC magnetron sputtering. The effects of the grain-shape, the crystallographic texture, the porosity and the Wβ volume fraction on the macroscopic elasticity constants were studied. Among all these effects, it was found that the effect of the Wβ volume fraction was the most pronounced. The effects of the crystallographic and morphological texture on the microscopic elastic behavior of the film were evaluated. No dominance of the crystallographic or morphological texture effect was observed and their contributions depend on the crystallographic plane and the measurement direction.
Schematic representation of the methodology used in the determination of the single-crystal elasticity constants. Display omitted
Material extrusion (MEX) of metallic components is an indirect additive manufacturing (AM) process that is recently gaining a lot of attention in the industry. This multi-step process with debinding ...and sintering, provides an inexpensive safe alternative, that is effective, flexible and office-friendly for several corporations compared to other metal AM techniques. However, optimizing the manufacturing parameters of the MEX process is still challenging due to the lack of research on their impact on the mechanical and surface properties of the fabricated materials.
For this purpose, this paper investigates how various processing parameters impact the mechanical properties and surface roughness of 17-4 PH stainless steel parts produced by MEX. The parameters analyzed include layer thickness, build orientation, number of contours, and aging thermal treatment for 1 h at 482°C (H900). A Taguchi design of experiments (DoE) was employed to conduct the parametric analysis and the results were post-evaluated via the analysis of variance (ANOVA). The experimental results show that H900 treatment increases the micro-hardness by ∼50 HV0.3 and contributes in augmenting the ultimate tensile strength (UTS) by ∼200 MPa. The build orientation and its interaction with the layer thickness have the highest impact on the surface roughness. Moreover, the amount of enclosed porosity is higher in the samples with lower layer thickness. The absorbed impact energy (Wabs) is relatively low due to the enclosed porosity content and is not linked to the analyzed processing parameters. The best mechanical properties were obtained for parts built with solid infills, 0° build orientation, 0.125 mm layer thickness, two contours, and H900 as a post-treatment.
In this study, simulation and experimental methods were used to investigate the influence of cold spray conditions on AISI 316L stainless steel coatings. The effect of both helium and nitrogen gases ...used was investigated. The temperature, particle sizes of spraying powder, and distance from the nozzle throat to the impinging point were estimated by using the Kinetics Spray Solutions GmbH software. The 316L stainless steel (SS) coatings were examined by X-ray diffraction, Scanning Electron Microscopy and Energy Dispersive X-Ray Microanalysis. The tribological behavior was evaluated under different loads (2 N and 5 N) in dry conditions. It was found that the nitrogen and helium propellant gas with high speed and fine particles led to produce good coatings with dense microstructures. From the nanoindentation experiments, the Young's modulus and hardness of the SS 316L samples were enhanced of about 8% with helium due to the high particle velocity. It was shown that the wear resistance of SS 316L produced with helium was higher than that of the standard SS 316L coatings. The coatings produced with helium revealed lower friction coefficient (0.65) and wear rate (6.9 × 10
–4
mm
3
/Nm) under 2 N applied load than that obtained nitrogen. It was also found that the SS 316L cold sprayed by helium with dense structure presents high hardness and good tribological performance that can be suggested for several applications.
Graphical Abstract
The structural, magnetic, electronic, optical and mechanical properties of lanthanum chromite LaCrO
3
were investigated in cubic (Pm-3m) and orthorhombic (Pbnm) phases by the first-principles method ...based on the density functional theory. In this study, the WC-GGA with additional Hubbard potential U and Tran–Blaha-modified Becke–Johnson potential (TB-mBJ) were used. The structure optimization was accomplished for ferromagnetic (FM), A-type (A-AFM), C-type (C-AFM) and G-type (G-AFM). Both O-LaCrO
3
and C-LaCrO
3
phases were stable in the G-AFM state. The density of states and band structure revealed the existence of a wide band gap calculated with GGA + U and TB-mBJ, these two methods provide the accurate results for the band gap which are in good agreement with experimental values. The dielectric functions and optical proprieties were also calculated such as the absorption coefficient, refractivity index and the energy loss function. The elastic properties such as bulk modulus, shear modulus, Young’s modulus and Poisson’s ratio as well as the anisotropic factors were investigated. It has been shown that O-LaCrO
3
and C-LaCrO
3
phases were mechanically stable. Finally, the average sound velocity and the Debye temperatures of LaCrO
3
were evaluated.
Diamond-like carbon (DLC) and titanium-doped DLC coatings were prepared by hybrid PECVD/direct current magnetron sputtering (DCMS). In this study, we show that the operating conditions of ...titanium-doped DLC coatings used for implants in surgical devices significantly modify their surface properties and consequently their interaction with cells. The coatings showed uniform distribution on the substrate and their biocompatibility was tested by way of rat
calvaria
osteoblasts. Doping DLC with Ti changed the roughness and wettability of the film interface. The autoclaving of the samples led to the surface oxidation and the formation of TiO
2
on the top-most layers of Ti-doped DLC. This was quantitatively assessed by X-ray photoelectron spectroscopy (XPS) and revealed the presence of Ti
3+
and Ti
4+
species in
redox
reactions during their interactions with cells. By XPS analysis, the oxidative carbonaceous species C=O and O=C–C were detected during the bacterial inactivation. Reactive oxygen species (ROS) were identified on the sputtered samples and the
⦁
OH radical was identified as the most important oxidative radical intermediate leading to bacterial disinfection. The position of the intra-gap of the oxidized C species is suggested within the TiO
2
bandgap.
Mimicking naturethrough nanostructuring allows the creation of multifunctional surfaces withremarkable properties, such as anti‐reflectivity, high optical transmittanceand controlled wettability, ...enabling anti‐icing or anti‐fogging behaviors. These multifunctionalsurfaces have gained significant interest in civil and military domains. However,integrating them into real‐life applications faces challenges related tocost, high‐throughput large‐scale compatible nanofabrication techniques, andtheir mechanical resistance. While sub‐wavelength patterning improves the optical performance,it often comes at the cost of compromising the mechanical resistance. As opticalperformance improves, mechanical resistance tends to deteriorate, and viceversa. To address this challenge, taking inspiration from the lotus leafstructure, where patterns are covered by a thin 2D wax film, covering thepatterns of structured surfaces with a protective layer can be a viablesolution. This protective layer should enhance the mechanical resistance of thesurface without compromising its multifunctional capabilities. This reviewhighlights the most suitable materials that can be employed as protectivecoatings and their potential to enhance the resistance of structured surfaces.The fundamental concept behind the creation of multifunctional optical surfacesis discussed, followed by a comprehensive examination of mechanical tests thatcan be utilized to characterize their mechanical behavior. This review aims topave the way for the development of durable multifunctional optical surfaces,making them more amenable to industrial applications.
The mechanical resistance of multifunctional optical surfaces can be enhanced through hard coatings. This review provides a wide range of potential hard and transparent materials with different deposition approaches. A detailed and comprehensive roadmap for selecting the ideal material and the best pattern geometry is also described to fully unlock the application of these surfaces in harsh environments.
The development of cost-effective materials for fabricating electrodes is crucial for drug, pharmaceutical and environmental applications. This paper presents the synthesis and characterization of a ...novel polyketimine (PKI) membrane obtained by condensing partially of different weight percentages of oxidized polyvinyl alcohol and aminated polyether sulfone. Using the PKI membrane as a scaffold, we introduced laser-induced graphene electrodes (LIGEs) for the efficient electrochemical sensing of paracetamol (PCM), which serves as a model drug. Electrochemical measurements were conducted to assess the physico-chemical properties, including laser-induced porous graphene features, such as the heterogeneous electron transfer (HET) rate and electrochemically active surface area (ECSA). The obtained results demonstrate that the LIGEs exhibit excellent performance in PCM sensing, showing a linear detection range of 50-600 µM with a detection limit (LOD) as low as 14.3 µM and a good selectivity toward uric acid. Furthermore, the functionalization of the electrode surface with AuNPs improved the electrode physico-chemical properties (HET and ECSA) and lowered the detection limit down to 1.1 µM. Consequently, these affordable electrodes hold great potential for analysing other drugs and detecting heavy metal cations in various applications.
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.
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