Layers Of Different Thicknesses Research Articles

Influence of surface texture and coating thickness on adhesion of nickel plated coatings to aluminium substrate

Adhesion of coating to substrate has been a challenge due to the hybrid effects induced by surface roughness. In this study, the adhesion of electroplated nickel and electroless NiP layers of different thicknesses ranging from 5 to 20 μm, as metal coatings, applied to aluminium substrates of different surface conditions, has been evaluated. Different processes including grinding, polishing, sandblasting and laser surface texturing were used to produce a series of roughness/surface textures on the substrate coupons. Adhesion of the coatings was assessed by bending test qualitatively as well as semi-quantitatively. It was found that surface texture isotropy/anisotropy (value of <0.1 and >0.8) and skewness significantly affect the delamination of plated coatings. With the increase in layer thickness, it was realized that the coating cracks and delamination increased and adhesion strength decreased by 14 % on average.

The effect of sand-crumb rubber mixture treatment on the seismic response of a low-rise building located on liquefiable soil

One of the most effective measures to reduce earthquake risks in high-seismic areas is to reduce the input forces caused by earthquakes to the structure. The properties of rubber materials in geotechnical projects are energy absorption, dynamic deformation change as well as damping of latent energy in loads, high shear modulus and damping ratio, easy access and their economic nature. In this research, with finite difference modeling, the effect of using sand- crumb rubber layer on the seismic behavior of the model has been obtained. In the following, by changing the thickness and depth of the sand-crumb rubber layer, the seismic behavior such as floor displacement and internal forces have been investigated. This research numerically models liquefaction (UBCsand with FLAC) and predicts the effects of the sand-crumb rubber layer of different thicknesses (as % weight of the mixture) under the foundation and evaluates the structure's damage and settlement interacting with the soil by validating the numerical model with the laboratory model and calibrating it with different ratios. The results show that liquefaction, pore water pressure excess ratio and soil settlement will be significantly reduced with the presence of sand-crumb rubber layer, and also the base shear has shown an increase, but the structural damage is reduced.Graphical

Optimal permeance ratio, flux direction and layer distribution in composite asymmetric membranes composed of sequences of layers obeying real-power flux laws

In this study, the optimal permeance ratio and layers distribution in multilayer membranes and thin films in which each layer obeys the following real-power law: Flux=πi(P1,ini−P2,ini) are determined for any positive real values of ni. Such an exponent has a physical meaning in several cases, such as: diffusion-controlled permeation of hydrogen in metal membranes i) under infinite-dilution conditions (n = 0.5), and ii) under higher-concentration ones (0.5 < n < 1.5), iii) desorption-limited permeation (n = 1) in the same type of membranes, Knudsen-type diffusional mechanism (n = 1) and viscous flow (n = 2) in microporous membranes. Furthermore, n is equal to 4 in radiation-driven thermal flux. The work considers two generic layers of different thicknesses and exponents, for which it is proven the existence of a general optimal permeance ratio π1/π2 maximising the flux ratio, which is found to be equal to the inverse of the ratio between the respective maximum theoretical driving forces that can be established in each layer. Such an optimal permeance ratio is also proven to be a global optimum. Afterwards, we provide a theoretical generalisation of this optimality to whatever types of driving forces. Then, we provide a demonstration that the highest species permeating flux is always established when feeding it from the layer side with the highest exponent independently of the permeance ratio. As an important consequence, to maximise flux, a multilayer membrane/thin film should be fabricated by depositing the layers in cascade according to the ascending or descending exponents, and should be used in a configuration in which the flux flows from the layer with the highest pressure exponent to the layer with the lowest one. It is also shown that there exists an optimal value of the lower exponent n1 that maximizes the flux ratio keeping constant the other parameters. Finally, we showed that a virial-type linear combination of polynomial driving forces can be approximated by the empirical flux law investigated. Overall, our results are valid not only for whatever type of composite membranes and thin films (metallic, ceramic, polymeric and hybrid ones), but also for any sequential system involving a flux of whatever physical entity obeying the aforementioned law, such as heat transfer in the presence of radiation, non-linear electrical resistances and possible others.

Toward Tectonic-Type and Global 1D Seismic Models of the Upper Mantle Constrained by Broadband Surface Waves

ABSTRACT The unprecedentedly dense current sampling of the upper mantle with seismic data offers an opportunity for determining representative seismic velocity models for the Earth’s main tectonic environments. Here, we use over 1.17 million Rayleigh- and 300,000 Love-wave, fundamental-mode, phase-velocity curves measured with multimode waveform inversion of data available since the 1990s, and compute phase-velocity maps in a 17–310 s period range. We then compute phase-velocity curves averaged over the globe and eight tectonic environments, and invert them for 1D seismic velocity profiles of the upper mantle. The averaged curves are smooth and fit by VS models with very small misfits, under 0.1%, at most periods. For phase-velocity curves extending up to 310 s, Rayleigh waves resolve VSV structure down to the shallow lower mantle. Love-wave sampling is shallower, and VSH and, thus, radial anisotropy profiles are resolved down to 375–400 km depth. The uncertainty of the VS models is dominated by the trade-offs of VS at neighboring depths. Using the model-space-projection approach, we quantify the uncertainty of VS in layers of different thickness and at different depths, and show how it decreases with the increasing thickness of the layers. Example 1D VS models that fit the data display the expected increase of the lithospheric seismic velocity with the age of the oceanic lithosphere and with the average age of the continental tectonic type. Radial anisotropy in the global and most tectonic-type models show a flip of the sign from positive (VSH&amp;gt;VSV) to negative at 200–300 km depth. Negative anisotropy is also observed in the shallow mantle lithosphere beneath oceans down to 45–55 km depth. We also compute a global model with the minimal structural complexity, which fits the data worse than the best-fitting one but does not include a sublithospheric low-velocity zone, providing a simple reference for seismic studies.

Formation of Highly Tunable Periodic Plasmonic Structures on Gold Films Using Direct Laser Writing

AbstractDirect laser writing method is a promising technique for the large‐scale and cost‐effective fabrication of periodic nanostructure arrays exciting hybrid lattice plasmons. This type of electromagnetic mode manifests a narrow and deep resonance peak with a high dispersion whose precise controllability is crucial for practical applications in photonic devices. Here, the formation of differently shaped gold nanostructures using the direct laser writing method on Au layers of different thicknesses is presented. The resonance peak is demonstrated to be highly dependent on the shape of the structures in the array, thus its position in the spectra, as well as the quality, can be additionally modulated by changing the morphology. The shape of the structure and the resonance itself pertain not only on the laser pulse energy but also on the grating period. This overlapping effect occurring at distances smaller than the diameter of the focused laser beam is studied in detail. By taking advantage of the highly controllable plasmonic resonance, the fabricated gratings open up new opportunities for applications in sensing.

Numerical Modelling of Bearing Strength of Concrete Strengthening with Carbon Fibre Reinforced Polymers (CFRP) Wrapping for Different Thickness of CFRP Sheet

The bearing strength of concrete plays an important role in transmitting the bearing force into the structural supports, especially for buildings and infrastructure such as concrete footings, concrete bridges, column corbels and concrete connections. The structural behaviour of the concrete bearing is related to the confinement effect, in which the load is transmitted to the concrete surface through the contact interaction between the steel bearing plate. However, extreme penetration on the contact surface of the concrete blocks by the steel bearing plate leads to failure modes on the concrete block. This research study focuses on the performance of the bearing strength of the concrete when it is wrapped with carbon fiber-reinforced polymers (CFRP) as the strengthening method. This research also examines the bearing strength of concrete when it is wrapped with a single layer of different thicknesses of CFRP sheet, which range from 1mm to 4mm thick. In order to understand the concrete bearing performance, a finite element model (FEM) using ABAQUS/CAE software is developed. An optimum meshing with a size 12.5mm is used for the further nonlinear analysis of the concrete model to discuss the results, such as the model validation by comparing the bearing strength results from the FE model with the Australian Standard, the comparison of the load-displacement curve for different thicknesses of CFRP wrapping, as well as the structural response or visualization of the concrete model. From the results, it shows that the different thicknesses of the CFRP wrapping significantly have a positive impact on the bearing capacity of the concrete, where the bearing strength of the concrete increases up to 26.16% as the thickness of the CFRP wrapping increases to 4mm for the optimum meshing size of 12.5mm. The FE visualization also shows various structural responses of the concrete bearing in the context of the deformation shape, vertical displacement, vertical stress distribution and max and minimum principal stress distribution of the concrete bearing, which are further discussed in this report

Titanium adhesion layer influence on the formation of hybrid lattice plasmon structures via laser-direct writing

The field of nanotechnology is attracting increasing attention due to the successful use of nanostructures in sensor fabrication and the development of new optical devices. Various lithography techniques can be employed to produce nanostructures, but the most recent technique, laser-direct writing, provides efficient and precise control over structural parameters, which is crucial for achieving and optimizing optimal plasmonic properties. In this work, plasmonic structures were formed on a thin gold surface using adhesive titanium layers of different thicknesses, which improve the adhesion between the gold coating and the substrate. The plasmonic properties of the formed structures were assessed to determine the influence of the titanium layer on the quality of plasmonic resonance. The plasmonic structures formed with the titanium adhesion-enhancing layer exhibited high-quality values of plasmonic resonances comparable to those of the structures without the adhesion layer. This property is particularly relevant for the development of plasmonic sensors, as increased adhesion of laser-induced structures increases the durability of this type of sensors.

Seismic Failure Mechanisms of Concrete Pile Groups in Layered Soft Soil Profiles

So far, little attention has been paid to the investigation on the seismic failure mechanisms of flexible concrete pile groups embedded in the layered soft soil profiles considering the material non-linearities of soil and concrete piles. The purpose of this study is to investigate seismic failure mechanism models of flexible concrete piles with varied groups in silt layered loose sand profiles under horizontal strong ground motions. Three-dimensional finite element models of the pile–soil interaction systems, which include nonlinearities of soil and concrete piles as well as coupling interactions between the piles and soil, were created for Models I, II, and III of the soil domains, encompassing 1x1, 2x2, and 3x3 flexible pile groups with diameters of 0.80 m and 1.0 m. Model I consists of a homogenous sand layer and a bedrock, Models II and III are composed of a five-layered domain with homogeneous sand and silt soil layers of different thicknesses. The linear elastic perfectly plastic constitutive model with a Mohr–Coulomb failure criterion is considered to represent the behavior of the soil layers, and the Concrete Damage Plasticity (CDP) model is used for the nonlinear behavior of the concrete piles. The interactions between the soil and the pile surfaces are modeled by defining tangential and normal contact behaviors. The models were analyzed for the scaled acceleration records of the 1999 Düzce and Kocaeli earthquakes, considering peak ground accelerations of 0.25 g, 0.50 g, and 0.75 g. The numerical results indicated that failure mechanisms of flexible concrete groups occur near the silt layers, and the silt layers have led to a significant increase in the spread area of the damaged zone and the number of damaged elements.

Microstructure and physical properties of black-aluminum antireflective films.

The microstructure and physical properties of reflective and black aluminum were compared for layers of different thicknesses deposited by magnetron sputtering on fused silica substrates. Reflective Al layers followed the Volmer-Weber growth mechanism classically observed for polycrystalline metal films. On the contrary, the extra nitrogen gas used to deposit the black aluminum layers modified the growth mechanism and changed the film morphologies. Nitrogen cumulated in the grain boundaries, favoring the pinning effect and stopping crystallite growth. High defect concentration, especially vacancies, led to strong columnar growth. Properties reported for black aluminum tend to be promising for sensors and emissivity applications.

Fire and Explosion Hazard Aspects for Bucket Elevators

Technological installations for the vertical transport of cereal products, are affected by the presence of combustible dusts that can be mixed with air, in suspension, or in the form of dust layers of different thicknesses. The presence of these combustible dusts is a constant danger of fires or even explosions. In combustible dusts are swirled in the air in concentrations in their explosive range and there is also an ignition source, the dusts can burn quickly and even give rise to explosions, in which case the force and pressure developed is considerable. Since, in most cases, following a fire and especially a combustible dust explosion, the damage caused is quantified by immeasurable material damage and even by recording human losses, special attention must be paid to how they are identified and implemented protection and prevention measures to prevent fires and combustible dust explosions. In this paper, the principles and main factors that must be considered when quantifying the risk of fire and/or explosion for a bucket elevator used for the vertical transport of cereal products are highlighted. A number of recommendations for the safe use of these lifts are also presented.

Investigating ultra-thin Ag and Au layers using spectrophotometry and AFM imaging

A spectrophotometric method is demonstrated for refractive index and thickness determination of thin and ultrathin metallic films. The method involves a three-layer stack where the metallic layer of interest is deposited on an opaque Si wafer coated with SiO2. This stack creates oscillations in the reflectance spectrum, which are highly sensitive to the index of the metallic film, allowing precise determination of the index of layers down to 1 nm. Experimental index values are given for Ag and Au over the wavelength range of 370–835 nm. These results are correlated with Atomic force microscopy (AFM) images of the films, which reveal dramatic changes in structure for layers of different thickness.

Multilayered Inhomogeneous Beams under Torsion and Bending: An Analytical Study of Energy Dissipation

The present theoretical paper is devoted to the problem of energy dissipation in multilayered inhomogeneous beam structures of visoelastic behaviour. In particular, our attention is concentrated on studying the energy dissipation for the case of a beam that is loaded simultaneously in torsion and bending. Both torsion and bending moments which are applied on the beam change with time so that the angles of twist and rotation of the beam end vary continuously with time. The viscoelastic mechanical behaviour of the beam under torsion is treated by a viscoelastic model that has two linear springs and a linear dashpot. The model is under time-dependent shear stress. The viscoelastic behaviour of the beam under bending is modelled in a similar way. An analytical approach of deriving the energy dissipation is applied. The approach treats a multilayered beam that has an arbitrary number of layers of different thicknesses and material properties. The layers are longitudinally inhomogeneous. An investigation of the energy dissipation is carried-out to clarify the effect of the parameters of the time-dependent bending and torsion moments, the material inhomogeneity and the beam size on the energy dissipation.

Growth mechanism and field emission of B doped AlN films

This paper highlights the effect of boron dopant on the field emission and growth mechanism of AlN films. The films have been grown by reactive RF magnetron sputtering method. For undoped films, columnar AlN structure was obtained. In the case of boron doped AlN films, the structure growth proceeded gradually through four layers of different thicknesses and structures. It was found that boron favors the formation of an amorphous layer within which oxygen and boron based precipitates develops, retarding the growth of columnar morphology. Depth profiling X-ray photoelectron spectroscopy analyses confirm the presence of B-O, B-N, Al-B and Al-O groups.The study on the field emission (FE) properties of undoped and B doped AlN films on Si substrates indicates that the addition of boron allow to improve FE properties with low turn on field of 2.6 V/μm and low threshold filed of 3.07 V/μm. Such good field emission properties can be attributed to the formation of densely nanograined surface and the appearance of boron based groups.

Influence of Butter Layer Thickness on Microstructure and Mechanical Properties of Underwater Wet 16Mn/304L Dissimilar Welded Joint.

Butter layers of different thicknesses were successfully deposited on ferritic steel by using the tungsten arc welding (TIG) process. The effects of butter layer thickness on the microstructural characteristics, elemental distribution, and mechanical properties of underwater wet 16Mn/304L dissimilar welded joints were investigated. The results showed that the butter layer significantly changed the microstructure and elemental distribution of 16Mn/304L joints. As the thickness of butter increased, the heat-affected zone (HAZ) at the ferritic steel side changed from the original 16Mn steel to the ERNiCrMo-3 butter layer. The martensite content in HAZ also exhibited a downward trend. When the thickness of the butter layer exceeded 6 mm, the microstructure of HAZ at the ferritic steel side was composed of ferrite and pearlite, instead of quenched martensite. The microhardness of underwater dissimilar steel welded joints significantly reduced due to the absence of martensite. The addition of the butter layer increased the ultimate tensile strength from 515 MPa to 565 MPa. The results of this work could provide a robust basis for future applications of dissimilar steel structures.

Artificial tailoring of MI transition at LAO/STO interface with SrSnO3 buffer layer

Buffer layers, capping layers, gate voltage, etc., can all have a major impact on the interface conducting properties of oxide heterostructures; in some cases, the thickness of a layer significantly alters the transport properties. Here, we report the impact of the SrSnO3 buffer layer of different thicknesses at the LAO/STO interface. The metallic behavior is observed in heterostructures with a buffer layer thickness smaller than 4 uc and the interface becomes insulating for thickness ≥ 4 uc. XPS results showed that the oxidation state of the Sn atom had changed in the insulating samples.

Influence of combined electromechanical processing modes of 40Kh steel on its structure and hardness

The paper considers the effect of combined electromechanical processing in three different modes on the structure and hardness of the surface layers of 40Kh steel, which was in a normalized state (the original structure). The modes differ from each other by the different applied load and the number of pulses. The applied load in modes 1 and 2 (current strength 39 kA, pulse time 0.02 s, number of pulses 1) is 100 and 250 MPa, respectively. A distinctive feature of mode 3 compared to mode 2 is a greater number of pulses (two). Metallographically it was established that in all three cases a hardened surface layer of different thickness (from 300 to 1200 μm) with a hardness of 593 – 598 HV is formed, consisting of two zones (a surface zone with a structure of fine-needle martensite; a transition zone smoothly transitioning into the initial ferrite structure). The transition zone (treatment according to mode 1) in its structure contains martensite and ferrite. The transition zone (mode 2 processing) consists of a Widemannstett structure. A more substantial surface heating zone according to this mode (700 μm) in comparison with the processing according to mode 1 (300 μm) in combination with intensive heat removal contributed to the formation of a Widmanstett structure, which is defective and unacceptable for operation. The transition zone with the processing according to mode 3 has the structure of martensite and ferrite. The formation of a defective Widmanstett structure in the transition zone does not occur, since 2 times more pulses are used during processing than in mode 2. This contributes to the heating of the surface layer to a greater depth (1200 μm), and, consequently, the structure formation in the transition zone occurs from the intercritical interval Ag3 – Ag1 .

Effect of Carbon Layer Thickness on the Electrocatalytic Oxidation of Glucose in a Ni/BDD Composite Electrode.

High-performance non-enzymatic glucose sensor composite electrodes were prepared by loading Ni onto a boron-doped diamond (BDD) film surface through a thermal catalytic etching method. A carbon precipitate with a desired thickness could be formed on the Ni/BDD composite electrode surface by tuning the processing conditions. A systematic study regarding the influence of the precipitated carbon layer thickness on the electrocatalytic oxidation of glucose was conducted. While an oxygen plasma was used to etch the precipitated carbon, Ni/BDD-based composite electrodes with the precipitated carbon layers of different thicknesses could be obtained by controlling the oxygen plasma power. These Ni/BDD electrodes were characterized by SEM microscopies, Raman and XPS spectroscopies, and electrochemical tests. The results showed that the carbon layer thickness exerted a significant impact on the resulting electrocatalytic performance. The electrode etched under 200 W power exhibited the best performance, followed by the untreated electrode and the electrode etched under 400 W power with the worst performance. Specifically, the electrode etched under 200 W was demonstrated to possess the highest sensitivity of 1443.75 μA cm-2 mM-1 and the lowest detection limit of 0.5 μM.

Magnetoelectric response in laminated BaFe12O19/Pb(Zr,Ti)O3 composites

The magnetoelectric (ME) response of laminated composites consisting of BaFe12O19 and Pb(Zr,Ti)O3 ceramics is systematically investigated. A butterfly-shaped curve of a magnetoelectric coefficient emerges in both three-layer and multilayer composites. We show that the appearance of a 7 ppm residual strain in the BaFe12O19 layer after magnetization is the main reason for this special curve. We also observe the self-biasing effect of the composites and a maximum ME response from 0.6 to 5 mV/(Oe cm) in laminated composites with magnetic and ferroelectric layers of different thicknesses that can be measured at a zero-bias magnetic field. The repeatable and stable maximum and minimum values of the magnetoelectric coefficient can be obtained under periodically applied biasing magnetic fields, which is important for a practical device application. An electric-field control of ferromagnetism, evidenced by a 17%–19% enhancement in the magnetization of the BaFe12O19 layer after Pb(Zr,Ti)O3 is polarized, is observed in the composites, implying potential applications in memory devices for the composites. Our work indicates that both magnetic field-controlled polarization and electric-field-controlled magnetization exist in BaFe12O19/Pb(Zr,Ti)O3 laminated composites.

Интерпретация археологических памятников на основе сегментации данных многозональной аэрофотосъемки

Comprehensive study of a large territory is necessary for a reliable assessment of the boundaries of archaeological sites, the territory of which has been used as agricultural land for a long time. Multispectral remote sensing data are an effective tool for identifying areas of the cultural layer of different thickness and structure. The considered algorithm of multispectral data processing includes three main stages

Investigation of DC and RF characteristics of spacer layer thickness engineered recessed gate and field‐plated III‐nitride nano‐HEMT on β‐Ga2O3 substrate

AbstractIn this work, a field plated recessed gate III‐nitride HEMT on β‐Ga2O3 substrate is proposed using AlN spacer between AlGaN and GaN layers. The two‐dimensional electron gas (2DEG) transport characteristics, input/output, and RF characteristics of the proposed HEMT with AlN spacer layer of different thickness (1, 2, 3, 4, and 5 nm) are numerically simulated and compared with HEMT without spacer layer. The 2DEG, which is created at the junction of AlGaN/GaN, plays a crucial role in the operation of GaN HEMTs. With the help of AlN as spacer layer between AlGaN and GaN, an augmented 2DEG concentration is accomplished owing to its large conduction band offset, high polarization effect, and higher barrier. Additionally, the inclusion of AlN spacer layer shifts the 2DEG density away from interface, resulting minimized interface scattering which results into greater mobility. The HEMT exhibited a mobility of 1261 cm2/Vs, threshold voltage of −0.45 V, drain current of 1.12 A/mm, breakdown voltage of 149 V, and excellent RF characteristics, that is, cut‐off frequency (maximum oscillation frequency) of 384 GHz (546 GHz) using 2‐nm AlN spacer layer. The proposed III‐nitride HEMT on β‐Ga2O3 substrate with 2‐nm AlN spacer can be used for RF/microwave and high‐power nanoelectronics applications.