Multilayer Surface Research Articles

Impact Abrasive Wear Property of CrAlN/TiSiN Multilayer Coating at Elevated Temperatures.

The impact wear property of hard coatings at elevated temperatures is of particular interest for applications in nuclear power plants. This study evaluated the impact wear behavior of two CrAlN/TiSiN coatings with and without sand. Alternately grown CrAlN and TiSiN films with modulation periods of 455 and 19 nm were formed in a columnar structure. The nanomultilayer shows better impact wear resistance than multilayer films with and without sand. The energy absorption rate has a similar trend to wear rate, leading to lower rebound velocity and peak impact force of the nanomultilayer compared with that of the multilayer. CrAlN/TiSiN coatings can protect the 308L substrate from oxidation. The dominant impact wear mechanism without sand is plastic deformation, and this wear region can be defined as the percussive zone. Peeling occurs on the multilayer surface without sand after 104 percussions, leading to rapid oxidation of the 308L substrate at 500 °C. Due to the abrasion effect, the wear rate of the sample with sand increases by an order of magnitude compared to the sample without sand. The wear scar of the sample with sand can be divided into the mixing zone and the sand−affected zone from inside to outside. Fe oxides are formed beyond the unbroken coating, which may be related to the outward diffusion of Fe.

Prediction of TBM Disc Cutter Wear and Penetration Rate in Tunneling Through Hard and Abrasive Rock Using Multi-layer Shallow Neural Network and Response Surface Methods

Prediction of TBM Disc Cutter Wear and Penetration Rate in Tunneling Through Hard and Abrasive Rock Using Multi-layer Shallow Neural Network and Response Surface Methods

Numerical approach to design the graphene-based multilayered surface plasmon resonance biosensor for the rapid detection of the novel coronavirus

In this article, a graphene-based multilayered surface plasmon resonance (SPR) biosensor of (BK7/WS2/Au/BaTiO3/Graphene) is proposed for the rapid detection of the novel coronavirus (COVID-19). The proposed SPR biosensor is designed based on the angular interrogation attenuated total reflection (ATR) method for rapid detection of the COVID-19 virus. The sensor’s surface plasmon polaritons (SPPs) and the sensing region refractive index (RI) are changed, owing to the interaction of various concentrated ligand-analytes. The specific ligand is mechanized with the proposed sensor surface and the target analyte that has flowed onto the sensing surface. The proposed sensor is capable of detecting the COVID-19 virus rapidly in two different ligand-analytes environments, such as: (i) the virus spike receptor-binding domain (RBD) as an analyte and monoclonal antibodies (mAbs) as a probe ligand, and (ii) the monoclonal antibodies (IgG or IgM) as an analyte and the virus spike RBD as a probe ligand. Due to the binding of the target ligand-analytes, the concentration level of the sensing region is incremented. As the increment in the concentration level, the RI of the sensing medium increases, therefore the change in RI causes the shift in the SPR angle resulting in the output reflectance intensity. The performance of the multilayered SPR sensor is analyzed numerically using the finite element method (FEM) method. Numerically, the proposed sensor provides the maximum angular shift sensitivity at 230.77 deg/refractive index unit (RIU), detection accuracy (DA) at 0.161 deg−1, and the figure of merits (FOM) is at 37.22 RIU−1. In addition, with each additional graphene layer number (L), the proposed sensor exhibits the angular shift sensitivity increment (1 + 0.7L) times. The novelty of the proposed multilayer (BK7/WS2/Au/BaTiO3/Graphene) sensor is highly angular sensitivity, and capable of detecting the COVID-19 virus rapidly without a false-positive report.

Interaction of Blast Waves with Multilayer Surfaces and Multiphase Media

The possibilities and methods of attenuation of blast waves when they are reflected on any limiting surface in terms of the peak pressure and momentum of the compression phase are of real practical interest. This interest stems from the need to eliminate or maximally mitigate the harmful effects of accidental and terrorist explosions. Porous materials are widely used in a variety of engineering structures due to their superior energy absorption capacity and other advantages in mechanical and physical properties. But when the porous material was used in protective structures to resist an explosive shock wave or high velocity impact, the protective function of the porous material was questionable. There are data indicating both a weakening and an increase in the explosive load on the protected object, depending on the structure of the porous material, the thickness of the protective layer, the duration of the positive phase of the blast wave pressure.

Preparation and Characterization of Superhydrophobic Silane-Based Multilayer Surface Coatings on Aluminum Surface

Preparation and Characterization of Superhydrophobic Silane-Based Multilayer Surface Coatings on Aluminum Surface

Effect of doping engineering in TiO2 electron transport layer on photovoltaic performance of perovskite solar cells

Titanium dioxide (TiO2) is widely applied as an electron transport layer (ETL) in perovskite solar cells (PSCs) due to its remarkable potential ability of electron transfer and long-time stability in PSCs. However, the requirement of high annealing temperature and the existence of hysteresis effect in TiO2-based PSC devices hindered its future applicability in commercial photovoltaic. Recently, various new strategies such as the incorporation of interfacial layer between ETL and absorber, the development of multilayer ETLs, surface passivation, and doping of metal cations in TiO2 have significantly improved the device performance and long-term stability of PSC. Amongst, doping engineering in TiO2 ETL has received more attention due to improved charge transportation ability and elimination of hysteresis. Doping of new ions in ETL materials is the most efficient way to tailor the band structure and modulate the electron mobility. However, in most cases, the basic mechanisms of doping engineering in electron extracting materials are still lacking. The present featured article investigated the scientific requirement and challenges combined with doping engineering in TiO2 ETL.

Laminarin and sodium molybdate as efficient sustainable inhibitor for Q235 steel in sodium chloride solution

It is of great significance to develop high-efficiency and sustainable inhibitors for Q235 steel under neutral saline conditions. In this study, laminarin (LA) and sodium molybdate (SM) were developed as sustainable corrosion inhibitor for Q235 steel, their inhibition effect and synergistic mechanism in 3.5 wt% NaCl solution was studied by experimentally and theoretically. The results indicated that the complex inhibitor has the highest inhibition efficiency (i.e., 92.75% versus 72.68%) when LA concentration is 0.3 g/L and SM is 0.7 g/L. Electrochemical measurements showed that the LA–SM mixture was anode mixed inhibitor, and confirmed that LA and SM inhibitor have a good synergistic effect. SEM and SECM were conducted to explore the corrosion morphology of Q235 steel surface with LA–SM in NaCl solution. Synergistic mechanism revealed the composite inhibitor could produce multilayer surface protective film presumably leading to an enhanced corrosion inhibition.

Modeling Bistatic Coherent Scattering From Multilayered Rough Surface Using Its Effective Dielectric Constant at P- and L-Bands

This paper proposes a closed-form asymptotic solution for the bistatic coherent scattering of a multilayered rough surface structure based upon its effective dielectric constant (EDC) in specular direction. The EDC is modeled by establishing an equivalence of the coherent scattering between the multilayered rough surface structure and a half-space homogeneous medium. The scattering solution is then solved using the scalar Kirchhoff approximation (SKA) method. This new method is referred to as the SKA-EDC method, and it is applied to analyze the sensitivity of the EDC and coherent reflectivity to bare soils with realistic parameters at P- and L- bands. The result indicates that EDC can give different responses to the soil moisture variations with respect to the coherent reflectivity, enabling the potentials of root-zone soil moisture retrieval. At incidence angle smaller than 35°, EDC gives the same value for both polarizations, and the coherent reflectivity can show a significant response to soil at depths < 15-50 cm at 0.80 GHz and <5-15 cm at 1.57 GHz, depending on soil moisture. The simulation also demonstrates that subsurface roughness has a trivial effect on the EDC and coherent reflectivity for three-rough-surfaces separated by continuously dielectric profiles. Subsurface can thus be assumed to be flat for reducing uncertainty in soil moisture inversion algorithms when the subsurface roughness is unknown.

Reducing down-cycling of carbon fibre by fibre architecture preservation: Multi-layer fibre surface quality investigation

Carbon fibre has a high mechanical reinforcement capability associated with fibre architectures. However, it is significantly down-cycled in the current recycling practice as a result of a loss of fibre architecture. Without the use of chopping/shredding process, the architecture of carbon fibre can be preserved, but the surface cleanliness of recycled carbon fibre (rCF) is not clear. In this study, an investigation is carried out on the surface quality of architecture-preserved rCF obtained from multiple layers of a carbon fibre reinforced polymer (CFRP). Carbon fibre woven fabrics are manufactured into CFRP, recycled using a pyrolysis technique, and inspected using visual and microscopic techniques. The results indicate a good preservation of fibre architecture in all five layers of CFRP. Nonetheless, the residue from the pyrolysis of resin is increased in the internal layers (4th and 5th) of rCF in comparison to the external layers (1st to 3rd). The results suggest that fibre architecture preservation has a potential to reduce the down-cycling of carbon fibre, but the impact is limited in internal fibre layers due to reduced fibre surface cleanliness. The insights from this study provide a further understanding on the approach to reduce the down-cycling of carbon fibre and move the carbon fibre industry towards circular economy.

A High-Temperature and Frequency-Reconfigurable Multilayer Frequency Selective Surface Using Liquid Metal

A high-temperature and frequency-reconfigurable multilayer frequency selective surface (FSS) based on liquid metal is proposed in this work. After construction of a multilayer dielectric cavity with specific dielectric-shaped pillars and the injection of liquid metal (EGaIn) into each layer of the cavity, the liquid metal and dielectric pillars form a slot-type bandpass FSS, and frequency reconfiguration is realized by switching the injection layer. A prototype of the proposed FSS was designed, fabricated and measured. The measured results validated the design well. The good conductivity and fluidity of the liquid metal are utilized to realize the reconfigurable electromagnetic performance of the proposed FSS. This works in the C-band (5 GHz) and Ku band (13 GHz) and has a frequency switching time between 13.1 to 14.2 s. Moreover, due to the good thermal conductivity of liquid metal, the flowing liquid metal can take away heat, and the multilayer FSS can work as cooling plate. The heat transfer performance was investigated by numerical simulations. A 1000 ° plane heat source was set on the bottom surface of the double-layer FSS. The average temperature on the top surface was 62.2 °, when the liquid metal fluid in the FSS had a speed of 1 m/s. The proposed multilayer FSS has strong potential for applications in some special application fields involving stealth and hypersonic aircraft.

Anchoring Co3S4 nanowires on NiCo2O4 nanosheet arrays as high-performance electrocatalyst for hydrogen and oxygen evolution.

The development of catalysts which can substitute expensive metals to efficiently split water is currently a hot research topic. Here, a multi-layered NF/NiCo2O4/Co3S4 nanocomposite was prepared on 3D porous nickel foam by hydrothermal and annealing processes. The electrode is a multi-layered, highly conductive and high specific surface area network without a binder, which facilitates electron transport and exposure of active sites, enhances full contact of the electrolyte/electrode interface, and accelerates H2 and O2 diffusion during water electrolysis. As expected, NF/NiCo2O4/Co3S4 exhibits surprising electrocatalytic activity, and only required 71 and 170 mV to reach 10 mA cm-2 in the hydrogen and oxygen evolution reactions, respectively, and exhibited stability up to 36 h. This strategy provides an efficient, durable, and low-cost bifunctional catalyst.

Ultrabroadband Metamaterial Absorber Based on Effectively Coupled Multilayer HIS Loaded Structure With Dallenbach Layer

An ultrawideband metamaterial absorber is demonstrated in the radar frequency range. The absorber features a thin thickness and outstanding broadband absorption performance. Effective absorption was obtained based on the loss of multilayer high-impedance surface (MHIS) loaded electromagnetic (EM) absorber and the Dallenbach layer. The impedance of the MHIS loaded EM absorber was analyzed to resolve the high-frequency broadband absorption. We explained the reason for the resonance shift of the Dallenbach layer and obtained the related impedance relation. Numerical simulations were carried out, and the results are in agreement with the theoretical analysis. We investigated the absorption mechanism by analyzing the distributions of electric and magnetic fields, and the standing wave effect on the surface of the resistive film is explained. Experiment characterizations have been carried out to demonstrate that the absorption is improved by the effective coupling of the Dallenbach layer. The absorption of the structure with magnetic material (MM) has been improved in the low-frequency range of 1–5.65 GHz with the maximum value of 92% at 2.44 GHz. A wonderful approach has been proposed: the Dallenbach layer placed under the MHIS loaded absorber fully exerts a low-frequency absorption effect to broaden the absorption band.

Sea Surface States Detection in Polar Regions Using Measurements of Ground-Based GNSS Interferometric Reflectometry

This article analyzes the interferometric measurements of ground-based global navigation satellite systems (GNSSs) stations and proposes a novel method for sea surface states detection. The novel technique benefits from a cost-effective data collection from a large number of global GNSS stations. In this study, we extend a traditional GNSS interferometry reflectometry (GNSS-IR) model so that it can be applied to a multilayer surface by considering the surface roughness, total reflectivity, and penetration loss in multilayer situations. Based on this model, the wavelet analysis is used to perform parameterization on the interferometric observations represented by the signal to noise ratio (SNR). An integration factor and power curve are also proposed to characterize the surface state transition. One-year data from an Arctic geodetic GNSS station in the north of Canada are collected for analysis to validate the proposed approach in comparison with the existing methods based on the amplitude and damping factors. The results show that the new method demonstrates good usability and sensitivity to detect surface state transitions, e.g., icing, snowfall, and snow melting. However, the amplitude and damping factor-based methods derived from the single-layer model are only able to detect the pure ice surface and cannot respond to thick snow conditions. Finally, the high-resolution spaceborne images confirm the reliability of this method, exhibiting a great potential for long-term coastal sea surface detection based on the global geodetic GNSS stations and later being expected to be applied to sense cryosphere surface states.

Design and analysis of SAW pressure sensing element based on IDT/AlN/Mo/diamond multilayered structure

The multilayer structure of surface acoustic wave sensor is an important development direction of surface acoustic wave devices in recent years. In this paper, the IDT/AlN/Mo/diamond structure of surface acoustic wave pressure sensing element is modeled and simulated. The influence of the thickness of AlN and IDT on pressure coefficient frequency andK2were simulated and analyzed. The performance of surface acoustic wave pressure sensing element is compared when the metal layer is Mo, no metal layer and the metal layer is Pt. Finally, the relationship between frequency variation and pressure of the designed multilayer surface acoustic wave pressure sensing element is obtained. This research provides a good guidance for the design of surface acoustic wave pressure sensor.

Active Control of Near-Field Radiative Heat Transfer between Nanoparticles and Slab Via the Multilayered Surface Modes

Active Control of Near-Field Radiative Heat Transfer between Nanoparticles and Slab Via the Multilayered Surface Modes

MANUFACTURING TECHNIQUE AND CONSERVATION TREATMENT OF A UNIQUE GILT-BRONZE STATUETTE EXCAVATED THROUGH RESTORATION OF THE STEP PYRAMID, SAQARA

Unexpected excavation of the Osirian statuette was inaugurated in 2021 during a conservation project at the first step in the western façade of King Djoser Pyramid which dates back to the Ptolemaic era. Varies strategies of the examination techniques, such as stereo and polarizing microscopes, and scanning electron microscopy coupled to energy dispersive X-ray spectrometry and X-ray diffraction were undertaken to characterize the chemical structure of gilt-layer, preparatory layer, and bronze alloy to evaluate their condition. This paper describes the actual condition of the statuette after excavation inside the King Djoser Pyramid, and characterization of the corrosion phases, and determines the best technique for conservation. Visual investigation revealed that the core of the bronze statuette was in good condition, but most gold with gesso was misplaced. Investigation and analyses results demonstrate that amazing technique which gilding has been accomplished as a thin layer over the white substrate from gesso. X-ray diffraction establishes that cuprite and atacamite resulting from the activation corrosion were the major minerals covering the statuette. Besides, calcite and gypsum were detected, which are to be a part of the preparatory layer. EDX results demonstrate that pure gold was likely used in the gilding layer. The gilt-bronze statuette was made of multi-layered surfaces. The solid cast was used in the crafting technique. Fixation of remaining plaster to metal was undertaken using Clucel G (4%). The figure was immediately treated via popular methods as mechanical tools and solvents. Benzotriazole inhibitor (3%) was used to cure the activation of bronze disease. The coating system was applied by using 3% paraloid B72. Finally, the statuette was preserved in the storage with the appropriate conditions.

Control of Specific/Nonspecific Protein Adsorption: Functionalization of Polyelectrolyte Multilayer Films as a Potential Coating for Biosensors.

Control of nonspecific/specific protein adsorption is the main goal in the design of novel biomaterials, implants, drug delivery systems, and sensors. The specific functionalization of biomaterials can be achieved by proper surface modification. One of the important strategies is covering the materials with functional coatings. Therefore, our work aimed to functionalize multilayer coating to control nonspecific/specific protein adsorption. The polyelectrolyte coating was formed using a layer-by-layer technique (LbL) with biocompatible polyelectrolytes poly-L-lysine hydrobromide (PLL) and poly-L-glutamic acid (PGA). Nonspecific protein adsorption was minimized/eliminated by pegylation of multilayer films, which was achieved by adsorption of pegylated polycations (PLL-g-PEG). The influence of poly (ethylene glycol) chain length on eliminating nonspecific protein adsorption was confirmed. Moreover, to achieve specific protein adsorption, the multilayer film was also functionalized by immobilization of antibodies via a streptavidin bridge. The functional coatings were tested, and the adsorption of the following proteins confirmed the ability to control nonspecific/specific adsorption: human serum albumin (HSA), fibrinogen (FIB), fetal bovine serum (FBS), carcinoembryonic antigen human (CEA) monitored by quartz crystal microbalance with dissipation (QCM-D). AFM imaging of unmodified and modified multilayer surfaces was also performed. Functional multilayer films are believed to have the potential as a novel platform for biotechnological applications, such as biosensors and nanocarriers for drug delivery systems.

Miniaturized Dual-Band Broadside/Endfire Antenna-in-Package for 5G Smartphone

This paper proposes a miniaturized antenna in package (AiP) for 5G millimeter-wave smartphone that incorporates broadside and end-fire arrays and supports a dual band covering 28 and 39 GHz. This paper demonstrates that the proposed AiP is 5.8 mm × 19 mm × 1.122 mm. It is believed that this is the smallest 5G AiP that can support a 10 dBi antenna gain, a 10 dB return-loss bandwidth of 3 GHz, and more than 10 dB isolation for both broadside and end-fire arrays. AiP consists of a 1 × 4 patch antenna array for broadside radiation and a 1 × 4 dipole antenna array for end-fire radiation. To miniaturize the patch antenna elements, a multi-layer Reactive Impedance Surface (RIS) is embedded between the patch layer and the ground plane. This multi-layer RIS idea greatly fits in 5G PCB-stack up antennas where each stack-up layer essentially requires certain portion of copper area. For the end-fire array antenna miniaturization with bandwidth improvement is achieved by modifying the Vertically Bent Folded Dipole Antenna (VBFDA) and adding a tightly-coupled T-shape side via wall. The AiP achieves a 10 dB return-loss bandwidth of 26.22 to 29.57 GHz and 35.18 to 41.00 GHz for Multi-Layer RIS Patch Antenna(MLRPA), and 26.40 to 29.74 GHz and 36.65 to 40.72 GHz for VBFDA. The antenna gain is 11.6 dBi for MLRPA and 10.0 dBi for VBFDA.

Electric field and strain induced gap modifications in multilayered GaN

Two-dimensional materials with a wide bandgap characteristic are critical to developing novel nanoscaled electronic devices. This study investigates the layer, in-plane biaxial strain, and vertical external electric field effects on the stability and electronic properties of multilayered GaN employing the density functional theory. Using structural optimization and phonon-mode calculations, the GaN structures with one to five layers are found to be stable and refer to the Born–Oppenheimer local minima. Under dimensionality effect, GaN unveils a semiconducting feature with an indirect bandgap at the HSE06 level that changes from 3.37eV for a monolayer to 2.79eV for a five-layered structure as the quantum confinement effect is reduced. The calculations demonstrate that the indirect bandgap of multilayered GaN decreases linearly when increasing the tensile strain. However, compressive strain engineering would induce an indirect-to-direct gap transition. Additionally, when the strength of the applied perpendicular external electric field to the multilayered GaN surface is increased, the GaN bandgap rapidly disappears due to the field-induced near free electronic gas. Calculated carrier effective mass indicate that both external effects impact charge carrier mobility as well. Such significant changes in the electronic properties under external excitations show that multilayered GaN shows promise in configurable nanoelectronic devices.

Volcanic ashe and its NaOH modified adsorbent for superb cationic dye uptake from water: Statistical evaluation, optimization, and mechanistic studies

The adsorptive performance of the natural Saudi Arabian volcanic ash (VA) and its NaOH-modified form (VA-NaOH) for Malachite green (MG) uptake from water were evaluated using response surface methodology (RSM) modeling technique and mechanistic aspects studies. The characterization analyses showed that both materials possess abundant functional groups (O–H, Si–OH, Si-O and Al-O), mineral salts (SiO2, Al2O3, CaO, Fe2O3, MgO), better surface characteristics leading to favorable adsorption of MG dye from water. The MG removals and the uptake capacities data were well described by cubic polynomial models with optimal condition at 25 °C, initial MG concentration of 120 mg/L, and pH 10 for VA and VA-NaOH. The kinetics of MG adsorption was best explained by pseudo-second order, while the Redlich–Peterson model fitted the equilibrium isotherms. The maximum Langmuir uptake capacity of 152 mg/g (VA) and 158 mg/g (VA-NaOH). The adsorption mechanism was speculated to be endothermic and involving both mono and multi-layer surface adsorption comprising chemisorption process (ΔG° = −27.6 to −33.9 kJ/mol), with increasing randomness scale at the liquid/solid interface without considerable entropy changes. The excellent regeneration ability, after successive cycles of desorption-adsorption, further indicates the high potential of the natural Saudi volcanic ash as excellent adsorbent for dyes removal from aqueous systems.