Nanostructured Coatings Research Articles

Sustainable Fabrication of ZnO Nanostructures for Enhanced Photovoltaic Performance: Insights from SEM and XRD Analysis

The study of sustainable ZnO nanostructure coatings for photovoltaic cells has advanced solar energy technologies. Hydrothermal and sol-gel methods were utilized to make ZnO nanorods, nanowires, nanoflowers, nanoplates, and nanotubes. These nanostructures have many shapes and crystalline arrangements. SEM revealed different shapes. The average length of nanorods, nanoflowers, nanoplates, and nanotubes is 150, 120, 200, and 160 nm, respectively. XRD verified crystal structures and dimensions. The 25–30 nanometer crystals have orientations of (002), (101), (103), (110), and (112). These nanoparticles greatly improved solar cell performance. Open circuit voltages were 0.65 V to 0.74 V, while short circuit currents were 11.3 mA to 13.5 mA. Power conversion efficiency ranged from 5.9% to 7.1%, while fill factors were 76% to 85%. A strong association exists between nanostructure morphology, structural properties, and cellular performance. This shows how these settings improve solar cell efficiency. These findings show that ecologically friendly ZnO nanoparticles have exciting potential. They point to efficient, ecologically friendly solar energy conversion methods. Research and development of customized nanoparticles may improve solar devices. This may provide eco-friendly and efficient solar energy systems.

Structure and Properties of Wear-Resistant Nanostructured Coatings Based on W, Cr and N

Structure and Properties of Wear-Resistant Nanostructured Coatings Based on W, Cr and N

Polymorphous nanostructured metallic glass coatings for corrosion protection of medical grade Ti substrate

Metallic glasses have received attention in the world of materials science and engineering due to their high mechanical and tribological properties. Thin film nanostructured metallic glasses have shown great prospects as surface coatings with increasing applications in biomedical areas for implants and surgical devices. In this work, we deposited titanium- and zirconium-based polymorphous thin film metallic glasses (Ti–Fe–Cu, Zr–Fe–Al, Zr–W–Cu) on medical-grade polished titanium substrate by co-sputtering using a PVD system. The corrosion behaviour of the films was investigated by exposing the samples to sterile simulated body fluid and examined using electrochemistry, microscopy, and spectroscopic analyses. The polymorphic properties of the films after exposure to simulated body fluid were observed by SEM and TEM. SEM analysis shows that the surface morphology of the exposed samples was found to vary significantly compared to their corresponding as-deposited samples. Electrochemical properties (Ecorr, Icorr, and OCV, impedance |Z|) demonstrated that the thin film metallic glasses were found to enhance the corrosion resistance of the substrate. Further investigations of the exposed films by XPS and Raman analyses have revealed that the induced oxide passive layer significantly enhanced the corrosion efficacy of the films on titanium substrate. Among the three samples, Zr–W–Cu coating has shown the highest corrosion protection almost 450 times better than the bare titanium substrate.

Silver/Graphene Oxide Nanostructured Coatings for Modulating the Microbial Susceptibility of Fixation Devices Used in Knee Surgery.

Exploring silver-based and carbon-based nanomaterials' excellent intrinsic antipathogenic effects represents an attractive alternative for fabricating anti-infective formulations. Using chemical synthesis protocols, stearate-conjugated silver (Ag@C18) nanoparticles and graphene oxide nanosheets (nGOs) were herein obtained and investigated in terms of composition and microstructure. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterizations revealed the formation of nanomaterials with desirable physical properties, while X-ray diffraction (XRD) analyses confirmed the high purity of synthesized nanomaterials. Further, laser-processed Ag@C18-nGO coatings were developed, optimized, and evaluated in terms of biological and microbiological outcomes. The highly biocompatible Ag@C18-nGO nanostructured coatings proved suitable candidates for the local modulation of biofilm-associated periprosthetic infections.

Nanomechanical characterization of nanostructured Lu2SiO5 environmental barrier coatings by nano-indentation

Nanostructured rare-earth silicates are widely considered as environmental barrier coatings for the new generation of silicon-based composites. In current work, the nanostructured Lu2SiO5 coatings were deposited successfully using nanostructured Lu2SiO5 feedstocks by atmospheric plasma spraying (APS). Moreover, the nanomechanical properties of Lu2SiO5 coatings were characterized systematically by nano-indentation. Results indicate that the grain growth of Lu2SiO5 coatings is not obvious compared to Lu2SiO5 feedstocks. The nanostructured Lu2SiO5 coatings exhibit bi-modal nanomechanical properties. The elastic modulus and nanohardness of Lu2SiO5 coatings are 148.84 ± 28.00 GPa and 8.51 ± 4.12 GPa, respectively. In addition, the elastic work and plastic work of Lu2SiO5 coatings are 10.387 ± 1.283 nJ and 18.437 ± 6.823 nJ, respectively. The proportion of consumption of energy of Lu2SiO5 coatings is 0.636 ± 0.099 during indentation, which means that nanostructured Lu2SiO5 coatings process an excellent wear resistance.

Coating of Filter Materials with CeO2 Nanoparticles Using a Combination of Aerodynamic Spraying and Suction.

Textiles and nonwovens (including those used in ventilation systems as filters) are currently one of the main sources of patient cross-infection. Healthcare-associated infections (HAIs) affect 5-10% of patients and stand as the tenth leading cause of death. Therefore, the development of new methods for creating functional nanostructured coatings with antibacterial and antiviral properties on the surfaces of textiles and nonwoven materials is crucial for modern medicine. Antimicrobial filter technology must be high-speed, low-energy and safe if its commercialization and mass adoption are to be successful. Cerium oxide nanoparticles can act as active components in these coatings due to their high antibacterial activity and low toxicity. This paper focuses on the elaboration of a high-throughput and resource-saving method for the deposition of cerium oxide nanoparticles onto nonwoven fibrous material for use in air-conditioning filters. The proposed spraying technique is based on the use of an aerodynamic emitter and simultaneous suction. Cerium oxide nanoparticles have successfully been deposited onto the filter materials used in air conditioning systems; the antibacterial activity of the ceria-modified filters exceeded 4.0.

ВИБІР ТЕХНОЛОГІЧНИХ ПАРАМЕТРІВ ЛАЗЕРА ДЛЯ ОТРИМАННЯ НАНОСТРУКТУР НА ІНСТРУМЕНТАЛЬНІЙ СТАЛІ У12А

According to the improved model of the thermal interaction of laser radiation and the processing material, a study of the change in the maximum temperature at different depths of the surface layer was carried out on the example of tool steel U12A. The rate of change of the maximum temperature and temperature stress as a function of the heat flux density of laser radiation (LV) was also studied. The range of LV density was taken within q=108...1011 W/m2 for different times of its action, which corresponds to the conditions for the possible occurrence of NS. The study of the dependence of the rate of change of the maximum temperature on U12A steel on the density of the heat flow at different depths showed that during all times of its action, rates of temperature change of more than 107 K/s are realized, which indicates that, according to this criterion, the formation of NS is possible over the entire range of densities heat flow and at all investigated depths. To determine the possibility of accelerating the formation of NS, the values of temperature stresses in the zone of action on U12A were calculated at a density of 108...1011 W/m2 at different depths with an action time of t=10-4 ...10-10c. Which showed that the direct formation of NS from the action of temperature stresses is practically impossible, however, at a time of 10-5...10-4 of their values, they approach those required at a heat flux density of 1011 W/m2. In order to determine the technological parameters that ensure the production of NS, spatial dependences of the volume of NS on the heat flux density and the time of its action were constructed for the radius of the spot R=10-6 m (Fig. 8) and R=5•107 m (Fig. 9) . It was determined that obtaining NS is more realistic for the size of the spot 5•107 m, although the probability of obtaining them is also low. In fig. 10 and 11 show similar dependences for the grain size on the heat flux density and the time of its action for the spot size R=10-6 m and R=5•107 m when acting on U12A tool steel. The obtained spatial pictures allow, knowing the required grain size, to choose the technological parameters that allow them to be implemented. All this will be required during the development of the technology for obtaining strengthening nanostructured coatings on the cutting tool.

Gas Sensitivity of Nanostructured Coatings Based on Zinc Oxide Nanorods under Combined Activation

Gas Sensitivity of Nanostructured Coatings Based on Zinc Oxide Nanorods under Combined Activation

Artificial intelligence-based model for physical-mechanical surface properties of nanostructured coatings

This article presents a computational numerical model for the simulation and analysis of quantum chemistry and Gibbs free energy theory using static (ANNS), dynamic (DANN), and chaotic neural networks (CANN). The model calculates the physical-surface mechanics of hardness, adhesion, and strength. They resulted in nanostructured metal coatings with electrodeposited chromium nanoparticles on low-carbon steel. The ANNS, DANN, and CANN simulations showed that model-obtained values for analyzed properties presented an approximation of 99 % concerning theoretical matters taken as base. Likewise, model accuracy was verified by comparison with reference data (datasheet). The proposed model is not limited to the analyzed case and provides consistent results for predicting surface physical-mechanical properties of electrodeposited coating-substrate arrangements, with a minimum error percentage of 1–1.5 % over learning.

Advanced Nanostructured Coatings Based on Doped TiO2 for Various Applications

For many years, TiO2-based materials and improving their properties in order to expand their application areas have been the focus of numerous research groups. Various innovative approaches have been proposed to improve the photocatalytic and gas-sensing properties of TiO2 nanostructures. In this review, we aim to synthesize the available information in the literature, paying special attention to the sol–gel technology, which is one of the most frequently used methods for TiO2 synthesis. The influence of dopants on the structural, morphological, optical, and electrical properties of TiO2 and the way to modify them in a controlled manner are briefly discussed. The role of shallow and/or deep energy levels within the TiO2 bandgap in the electron transport behavior of doped TiO2 is emphasized. Selected research on photocatalytic applications in water disinfection, wastewater treatment, and self-sterilizing coatings that contribute to improving the quality of human life and environmental preservation is highlighted. A survey of biosensors that are closely related to medical applications such as cancer detection, implantology, and osteogenesis is also provided. Finally, the pressing problems that need to be solved in view of the future development of TiO2-based nanostructures are listed.

Structural Color from Cellulose Nanocrystals or Chitin Nanocrystals: Self-Assembly, Optics, and Applications.

Widespread concerns over the impact of human activity on the environment have resulted in a desire to replace artificial functional materials with naturally derived alternatives. As such, polysaccharides are drawing increasing attention due to offering a renewable, biodegradable, and biocompatible feedstock for functional nanomaterials. In particular, nanocrystals of cellulose and chitin have emerged as versatile and sustainable building blocks for diverse applications, ranging from mechanical reinforcement to structural coloration. Much of this interest arises from the tendency of these colloidally stable nanoparticles to self-organize in water into a lyotropic cholesteric liquid crystal, which can be readily manipulated in terms of its periodicity, structure, and geometry. Importantly, this helicoidal ordering can be retained into the solid-state, offering an accessible route to complex nanostructured films, coatings, and particles. In this review, the process of forming iridescent, structurally colored films from suspensions of cellulose nanocrystals (CNCs) is summarized and the mechanisms underlying the chemical and physical phenomena at each stage in the process explored. Analogy is then drawn with chitin nanocrystals (ChNCs), allowing for key differences to be critically assessed and strategies toward structural coloration to be presented. Importantly, the progress toward translating this technology from academia to industry is summarized, with unresolved scientific and technical questions put forward as challenges to the community.

Simple Deconvolution Models for Evaluating the True Microhardness of Thin Nanostructured Coatings Deposited via an Advanced Physical Vapor Deposition Technique

This article discusses the micromechanical properties and true microhardness determination of nanostructured tribological coatings (NTCs) based on a multilayered alternating nitride/carbonitride bilayer substructure for transition metals. The constituent nitride/carbonitride bilayers in the superlattice structure of the NTC were alloyed with refractory metals, denoted as Me = Me1 or Me2= Cr, Hf, Nb, W, and Zr. The resulting NTC coatings were deposited onto 100Cr6 steel substrates using an advanced physical vapor deposition (PVD) technique, referred to here as high-power ion-plasma magnetron sputtering (HiPIPMS). The comprising crystalline nanometer-scale TiAlSiMe1-N/TiMe2-CN nanoparticles strengthened by Me additives significantly increased the NTC microhardness to over 3200 HV. The primary focus of this research was to determine the true microhardness of the NTC film samples. The apparent microhardness (Ha) of the film/substrate system for various NTC samples was measured during microindentation testing using the Vickers method. Nine NTC samples were tested, each generating a corresponding microindentation dataset containing between 430 and 640 imprints, depending on the specific NTC sample. These datasets were analyzed using three distinct empirical approaches: (i) the inverse power-law model (IPL-Model), (ii) the sigmoid-like decay model (SLD-Model), and (iii) the error function model (ERF-Model). The observed solid correlation between the proposed models and experiments suggests that the true microhardness estimates (Hf) obtained through the empirical mathematical modeling approach are reliable.

Development of trimetallic cobalt-nickel-vanadium oxide anticorrosion coatings for the protection of AA2024 Al alloy specimens against sodium chloride solutions

Trimetallic cobalt-nickel-vanadium oxide (CoNiVOx) thin films were fabricated on aerospace grade AA2024 Al alloy specimens to investigate their behavior as anticorrosion coatings in a sodium chloride (NaCl) medium. Compact and homogenous nanostructured CoNiVOx coatings were developed using aerosol-assisted chemical vapor deposition by varying the deposition duration from 45 to 150 min at a constant temperature (475 °C). The structure and composition of the trimetallic CoNiVOx thin films were comprehensively investigated using X-ray diffraction, transmission electron microscopy, scanning electron microscopy/energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy, which demonstrated the successful synthesis of CoO/NiO/VO composite materials. The electrochemical corrosion properties of the trimetallic CoNiVOx films in a 3.5 % NaCl solution were determined using Tafel extrapolation and impedance spectroscopic tests, whereas the electrochemical stability and localized corrosion characteristics were determined using scanning electrochemical microscopic analyses. This study demonstrates that the trimetallic CoNiVOx oxide layer fabricated for 150 min exhibited an effective barrier protection performance on Al surfaces against corrosive attack in NaCl media.

Antibacterial Nanostructured Coatings

Nanomaterials, which by definition must have at least one of their constituents at the nanoscale, can display unique optical, magnetic, electrical, mechanical, and other properties [...]

Synthesis and characterization of single-phase X2-Lu2SiO5 nanostructured feedstocks for advanced plasma-sprayed environmental barrier coatings

The objective of this work is to synthesize the single-phase X2-Lu2SiO5 nanostructured feedstocks for plasma-sprayed environmental barrier coatings (EBCs). Generally speaking, high-performance feedstocks are a prerequisite for obtaining high-performance coatings. The single-phase X2-Lu2SiO5 nanostructured feedstocks were fabricated by a nanopowder reconstitution method for the first time. The morphology and phase structure of X2-Lu2SiO5 nanostructured feedstocks were examined. The physical properties of X2-Lu2SiO5 feedstocks were evaluated. In addition, the thermal conductivity of nanostructured X2-Lu2SiO5 coatings was measured. Results show that the single-phase X2-Lu2SiO5 nanostructured feedstocks are successfully synthesized when the mole ratio of Lu2O3 and SiO2 nanopowder is 1:1.1 and the agglomerated powders are sintered at 1300 °C for 2 h. The nanocrystalline size of the X2-Lu2SiO5 feedstocks ranges from 40 to 70 nm. Moreover, the d10, d50 and d90 of X2-Lu2SiO5 feedstocks are 24.69 μm, 37.78 μm and 54.75 μm, respectively. The apparent density and tap density of X2-Lu2SiO5 feedstocks are 1.76 g/cm3 and 2.09 g/cm3, respectively. The thermal conductivity of as-deposited Lu2SiO5 coating is 0.78–1.20 W m−1 K−1 (30–1200 °C). Overall, the single-phase X2-Lu2SiO5 nanostructured feedstocks are the most promising feedstocks for advanced EBCs system in the future.

Electroplating of hydrophobic/hydrophilic ZnO nano-structural coatings on metallic substrates

In the present work, ZnO thin film is shown as a coating on an aluminum substrate. In order to synthesize ZnO thin films, electroplated Zn thin layers were thermally oxidized in atmospheric air for different times (1h–4h) at a fixed annealing temperature of 500 °C. The samples were characterized by scanning electron microscopy (FEG-SEM) equipped with energy dispersive x-ray analysis (EDX), a profilometer, x-ray diffraction (XRD), and Raman spectroscopy. The wettability properties of the synthesized films were evaluated by measuring the contact angle between the surface of the films and a deposited water drop (WCA). The FEG-SEM images show that the surface morphologies change throughout treatment time. The sample treated for 2 h shows flower-like microstructures with an average size of 100 μm, which are covered with spherical ZnO nanostructures with a size less than 50 nm. Measured surface roughness ranges from 5.800 μm to 6.560 μm. Layers thicknesses vary between 31 and 38 μm. Structural characterization by XRD demonstrates that the synthesized ZnO thin films were polycrystalline and have Wurtzite hexagonal structures, grown manly along the (101) plan. The estimated crystallite sizes are in the nanometric scale and reach their maximum value for the sample treated for 2 h. This annealing time corresponds to the low dislocation density (δ) and low lattice strain (ε), indicating fewer defects. The Raman analysis shows five normal vibrational modes, which correspond to the ZnO Wurtzite structure. It was possible to obtain both hydrophobic and hydrophilic surfaces; the shape and surface roughness of the as-prepared films had an impact on the results. The largest measured contact angle, of 97°, was obtained after annealing for 2 h at 500 °C.

Scalable and high throughput photothermal water disinfection with negligible CO2 footprint utilizing nanostructured carbon coatings

Water heating and disinfection with reduced energy and CO2 footprint demands new and efficient materials for solar-thermal conversion technologies. Here, we demonstrate nanostructured porous hard-carbon florets (NCF) as effective solar absorber coating achieving excellent photon thermalization efficiency (87%). Functional NCF coating on three-dimensionally tapered helical solar receivers generate high surface temperatures (up to 95 °C). Such ‘green-heat’ is channeled to heat water up to 82 °C that simultaneously results in water disinfection through thermal shock. Untreated lake-water with high turbidity (5 NTU), high bacterial load (106 CFU mL−1) and pathogenic fungi is effectively disinfected in a continuous flow process. Translating this, a fully automated SWAP prototype (solar water antimicrobial purifier), delivers bacteria free hot water at an output capacity of 42 L m−2 day−1 with the lowest CO2 footprint (5 kg L−1) in comparison to all other existing approaches (>40 kg L−1).

Effect of Surface Modification via Laser Irradiation on the Operability of Carbide End Mills When Cutting Aircraft Alloys

In modern aviation production, innovative hard-to-machine materials with unique physical and mechanical properties are being used increasingly. When processing such materials, the weakest link in the technological chain of production is the metal-cutting tool. In this paper, to improve the efficiency of the blade cutting of heat-resistant alloys, we propose the use of nanostructured multilayer wear-resistant coatings with subsequent laser processing of the cutting surfaces of the end milling cutters according to various schemes. In this case, an increase in the wear-resistant properties of the cutting edge by 15%–20% is provided due to the formation, at high temperatures, of secondary structures with increased wear resistance and a reduction of the temperature and force loading of contact processes. Methodologically, the work was carried out in several consecutive stages: the first stage was the determination of effective grades of wear-resistant coatings obtained via various installations with their subsequent laser processing during the «SharpMark™ Fiber» installation; at the second stage tribotechnical tests were carried out during the tribometer and adhesion installation; and in the third stage wear-resistant, temperature-force tests were carried out using milling machines in various cutting modes. According to the results of the field tests, the tool durability period was increased by 15%–20%.

Similarity and difference in machining at mixed scales using nanostructured coated tools milling hypoeutectoid carbon steel

There are similarities and differences when machining at the microscale and macroscale. One difference is the lack of significant heat generated at the microscale, which means that thermal barrier coatings are largely redundant. However, the mechanisms of wear are similar and different depending on machining parameters. In this study, it is discovered that nanostructured coatings play different roles at mixed scales, which are experimentally determined by measuring tool wear, chemical diffusion, temperature, and forces. The main findings show that macroscale wear is thermal in nature and that microscale wear is primarily tribological. The principal conclusions focus on redesigning microtools and nanostructured coatings to eliminate wear, developing standards that describe the action of microtools, and understanding how to calculate the minimum chip thickness that guarantees the formation of chips rather than burrs.

Corrosion-resistant nanostructured carbon-based coatings for applications in fuel cells based on bipolar plates

The paper reports on carbon coatings deposited by accelerated C60 ion beam irradiation onto the VT1-0 titanium alloy surface at different substrate temperatures, considering potential applications in fuel-cell bipolar plates. We identified the temperature range for forming a conductive carbon nanocomposite coating (CNC) at different accelerating voltages (Ua). The obtained CNC consists of graphite nanocrystals embedded in an amorphous diamond-like matrix. The nanocomposite containing ∼40% of sp3 bonds is formed at Ts = 300–400 °C under Ua = 6 kV. The increase in accelerating voltage to 8 kV reduces the temperature of the nanocomposite formation to Ts = 200 °C. Interface contact resistance (ICR) of a CNC coated titanium plate decreases to 2.6 ± 0.7 mOhm⋅cm2 at a sealing pressure of 1.5 MPa, which is close to carbon paper – graphite contact resistance. This low ICR value persists after prolonged corrosion tests. Tribological studies established high wear resistance and high adhesion of CNC to titanium substrate, showing potential for stable operation of coated bipolar plates in mobile applications. CNC allows to overcome the limitation of corrosion-caused ICR increase, which makes CNC-coated titanium a promising candidate to substitute gold-coated stainless steel as a raw material for bipolar plates of proton-exchange membrane fuel cells.