Surface Review and Letters

A novel technique based on image processing inspired by the simple assumption for the first time to assess the roughness of nanofibrous mats based on grayscale variations is proposed. The height of a nanofibrous mat in different regions of the surface is simulated by grayscale variations in the image while the relation between grayscale and height is obtained as a linear function. The roughness is obtained by measuring height variations in the surface profile. Statistical roughness parameters of nanofibrous mats are also obtained from direct measurement with roughness profilometry and atomic force microscopy (AFM) for comparison of the roughness of nanofibrous mats between direct measurement and proposed method. The AFM is the most suitable surface measuring instrument for roughness measurement on the nanofibrous mat. So that, in this study the relation between the obtained statistical roughness parameters and the AFM result follows a low coefficient of expansion. Therefore, the two methods give results in satisfactorily close agreement. This proposed method not only exhibits all mentioned advantages, but has also been very simple, accurate, and useful for surface roughness prediction in nanofibrous mats.

The main and new surface modification methods of activated carbon (AC) and their influence on application (adsorption capacity) were reviewed. Adsorption capacity is an important issue, contributing to hazardous substances environment management. According to literature, it is true that surface chemistry strongly affects adsorption capacity. Surface chemistry can be modified by several methods that lead to different activated carbon properties. Furthermore, adsorbate properties, and their relationships with surface structure, can impact adsorption properties. Surface modifications can be conducted by adding some atoms to the surface structure, making the surface more acidic or basic. Introduction of oxygen and ammonia atoms (chemical modification) are the main processes to make the surface more acidic and basic, respectively, although may bring chemical wastes to environment. Surface modification is done by chemical and physical modifications that lead activated carbons to present different properties. The main and new methods of chemical and physical modifications are compared and presented in this paper. Some new physical methods, like corona treatment, plasma discharge and microwave radiation, can be applied to cause surface modifications. Corona treatment can be a practical and new way to cause surface modification on an activated carbon surface.

The recent research is allied with the analysis of a thin layer, spreading over the nonlinear surface of a radially extended sheet. The temperature field has been taken with the accumulation of dissipation term. The similarity variables have been used to transform the basic flow equations into a set of nonlinear differential equations. The thickness of the spreading phenomenon has been taken as a variable. The approximate outcomes of the problem have been achieved using the optimal approach of the homotopy analysis method (HAM). The convergence of the HAM has been computed with numerical method. The impact of the variable thickness parameter $\beta$, generalized magnetic parameter $M$, Eckert number $Ec$ and $\text{Pr}$ on the spreading pattern and temperature field has been calculated and discussed. The attention has been paid to the important physical quantities of interest like the skin friction and Nusselt number under the effect of various embedded parameters.

In this work, the effects of activated time on the structural properties of plated plant fiber nonwoven sheet were investigated systematically using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Results showed that there existed a saturated adsorption state on the surface of sheet in the PdCl₂ solution. The adsorbed rate and saturated adsorption capacity increased with the increase of PdCl₂ concentration. As a result, the deposited quantity and crystallization characteristics of plated nonwoven sheets were firstly enhanced and then unchanged with increase of activated time. The Pd-adsorbed capacity reached saturation point when the activated time was 16min. The maximum plated quantity was 0.02 and 0.028g/cm² when the concentration of activating solution was 0.015 and 0.15g/L on the surface of sheet.

Zinc-coated steel wires (1–5 numbers) reinforced in LM6 matrix composites have been prepared by squeeze casting process. Microstructure, hardness, tensile strength, ductility and dry sliding wear behavior of composites have been investigated by varying sliding distance and load. Fracture surface of tensile specimens and worn out surface of wear samples have been examined using field emission scanning electron microscope (FESEM). The results reveal that hardness of composites increased with increasing distance from matrix to steel wires. Maximum hardness values of 751 VHN and 611 VHN are observed in steel wire and at the interface of steel wire — aluminium, respectively. Tensile strength of composites increased upto 24% by reinforcing three steel wires in matrix. During the wear test, weight loss, wear rate and coefficient of friction decreased with increasing number of wires embedded in matrix and increased with increasing sliding distance and load. LM6 aluminium alloy reinforced with five numbers of steel wires decreased the weight loss upto 17% as compared to matrix under 40N load and a sliding distance of 2000m. Fracture surface of tensile specimen shows dimple formation in matrix and broken wires are observed in composites. Worn surface of composites shows fine grooves, whereas delamination is observed in matrix. In general, reinforcement of zinc-coated steel wires in LM6 aluminium alloy exhibited better mechanical properties and wear resistance compared to matrix.

Tin-doped indium sulfide films were grown on glass substrates by spray pyrolysis technique at low different Sn:In atomic ratio in the starting solution and optimum experiment conditions ($T_s=340^{\circ }$C, S:$\mathrm{\text{In}}=2$). The tin to indium molar ratio Sn:In was varied from 0 to $4\times 10^{-3}$ in the solution. The obtained films with 2$\mu$m of thickness, are perfectly adhered, homogenous and uniform on the substrates. X-ray diffraction study reveals that all the films are formed in $\beta$ phase grown preferentially along (400). These films lose the orientation with increasing tin doping level. The crystallite size of undoped film was 48.8nm, which increases to 59.2nm corresponding to the film grown with Sn:$\mathrm{\text{In}}=4\times 10^{-3}$. Raman analysis shows different peaks related to In₂S₃ phase. Optical analysis shows that these films are transparent in the visible and near IR with a transmittance higher than 85%. The optical gap energy is found to be direct and varies from 2.61eV to 2.76eV with the increase of Sn:In ratio from 0 to $4\times 10^{-3}$. The films are $n$ type and Sn doping improves considerably their conductivity. The photoluminescence behavior of In₂S₃:Sn films was also studied.

The main objective of this paper is the realization and characterization of a new organic thin film semiconductor material through the use of an ideal mixture of Acetaminophen/Curcumin utilizing several characterization techniques. From optical analysis, we can conclude that our semiconductor material is comparable and shows good concurrency to the semiconductors applied in technologic applications. In fact, the analysis of the optical measurement (transmittance $T)$ conducting to the optical energy bandgap, $E_{\mathit{\text{g}}}$, it was found the optical bandgap is around to $2.6\pm 0.02$eV. In addition, by using the Wemple Didominico model it was found the dispersion energy E_D varied from 5eV to 7eV, the average bandgap $E_M$ separated the center of both bands occupied and unoccupied is around 4.5eV and the static refractive index $n_0$ varies from 1.3 to 2 and it dependent on the compactness and transparency of the material.

The inhibition effects of garlic extract on copper corrosion under a thin electrolyte layer (TEL) were investigated using weight-loss measurements, electrochemical methods and surface analysis. Results showed that the volatile organosulfur compounds of garlic extract, such as diallyl trisulfide and di-2-propenyl disulfide, among others, could adsorb on the surface of copper and have a significant inhibitory effect on copper corrosion. Garlic extract acted as a mixed-type inhibitor for copper under TEL. Surface analyses, such as scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS), were conducted to illustrate the inhibitive mechanisms of this plant extract under a TEL.

The amorphous oxygen-doped diamond-like carbon films were prepared by pulsed laser deposition. Compared with the pure diamond-like carbon film, there were much less graphite clusters on the surfaces of the oxygen-doped diamond-like carbon films, and the average transmission of the oxygen-doped diamond-like carbon films in the medium infrared band increased. However, some new absorption peaks in the infrared spectra of the oxygen-doped diamond-like carbon film were generated. Rapid annealing was experimented to remove the absorption peaks. XPS analysis showed that the fractions of the C–O and C=O bonds that generated the new absorption peaks were reduced more than the fractions of $s{p}^3$ bonds by rapid annealing at 400${}^{\circ }$C, and the absorption peaks in the medium infrared spectra decreased. It indicated that rapid annealing at right temperature during the right time could reduce greatly the absorption in the medium infrared band of oxygen-doped diamond-like carbon films.

A zero-emission electroless nickel plating bath was investigated, which consisted of nickel hypophosphite, hypophosphorous acid, lithium acetate, citric acid and maleic acid. The bath stability, bath life and plating rate were 68.0min, 8 cycles and 13.39$\mu$m/h, respectively. The Ni–P plating layer showed smooth appearance with lots of small continuous nodules, with 12.23wt.% phosphorus content. The electrochemical measurements showed that the deposit exhibited excellent corrosion resistance. All of these properties of the zero-emission plating bath and its deposit were better than those of the popular plating solution and its layer. It is most significant that the spent plating bath can be used directly as a raw material to prepare LiFePO₄/C materials, which conforms to the concept of circular economy.

The structural and magnetic properties of Fe₃Si films fabricated by layered sputtering on Si substrates dependent on the Fe/Si thickness ratio varying from 2:1 to 4:1 were investigated. X-ray diffraction (XRD) results show that over the whole range of the Fe/Si thickness ratio considered, all films consist of the polycrystalline Fe₃Si phase. The film produced with the Fe/Si thickness ratio of 3:1 shows relatively high structural quality. Scanning electron microscopy (SEM) images reveal that the film layer can be clearly observed and the thickness of the film layer at Fe/Si thickness ratio of 3:1 is the thinnest. From the analysis of the magnetization curves, all of these films exhibit ferromagnetic behavior at room temperature. The sample at Fe/Si thickness ratio of 3:1 shows a high $M_s$ value of $\sim$831emu/cm³, which is slightly lower than the bulk value of Fe₃Si. The variety of its coercive force $H_c$ is associated with the change of grain size $D$ through $H_c\propto 1∕D$, and the discrepancy between the $H_c$ values of these films and the bulk Fe₃Si is due to defects pinning magnetic domain. Meanwhile, the electrical resistivity remarkably decreases with the increase of the Fe/Si thickness ratio.

The amorphous nickel/carbon microspheres (Ni/C-MSs) were synthesized through dehydration and carbonization of glucose at high temperature and high pressure. The obtained Ni/C-MSs and the Ni/C-800-MSs (calcined at 800${}^{\circ }$C) were thoroughly characterized on morphology, composition and catalytic performance. It is found that the Ni/C-MSs showed good catalytic performance for hydrogen generation from aqueous H₃NBH₃ at room temperature. Urea was oxidized electrocatalytically by Ni/C-800-MSs in alkaline medium, indicating a viable method for wastewater remediation and simultaneous production of valuable hydrogen.

Surface potential is one of the key properties of charge retain ability and energy storage performance of cellular electrets. Based on charge simulation method (CSM), a high precision simulation algorithm of surface potential of functional dielectrics is proposed in this paper, which can be applied to the simulations of cellular polypropylene after high-voltage corona discharge. In order to validate the modeling, the surface potential of insulating polymer after corona discharge is measured by an electrostatic measurement system and compared with simulation results based on CSM and finite element method (FEM). The result shows that the numerical simulation based on CSM is well consistent with the experimental data, which indicates that the modeling based on CSM can be used in the calculation and analysis of charge storage ability of capacitor and electrostatic generator based on functional electrets. Moreover, as simulation based on CSM has higher precision than FEM, investigation of surface charge storage ability and prediction of electrostatic hazards of insulating dielectrics could be realized by using CSM.

This paper contains the results of the structural and spectroscopic characterizations of undoped and Cadmium-doped cobalt oxide thin films with different Co/Cd molar ratios (3%, 5%, 7% and 9%). The nanosized undoped and cadmium-doped Co₃O₄ thin layers were prepared using sol–gel process and deposited on glass substrates by dip coating. The changes caused by the incorporation of cadmium at different levels of doping have been highlighted by the techniques UV–Visible (UV–Vis) spectroscopy, Infrared (IR) spectroscopy, X-ray diffraction (XRD) measurements, SEM coupled EDX and impedance spectroscopy. From the UV–Vis spectroscopy analysis, it was found that all the films are two direct bandgap energies. The optical transmittance and the bandgap energy decrease with increase in Cd concentration. The XRD spectra confirm the films were polycrystalline with a cubic spinel structure. The results of the impedance spectroscopy show that the equivalent circuit of the synthesized samples is an RC parallel circuit.

Nowadays, the superior properties of carbon-based materials especially nano structural derivation like graphene and graphene oxide (GO) spot light to the researchers. The GO has been suggested as an alternate material in device miniaturization due to its atomic structure. The memristors and nonvolatile memories are settled in these categories as a solution for the scaling limitation problem in the Moor’s law. Therefore, the GO can influence the memristor performance and characteristics. The current–voltage characteristics as the most significant parameter in the memristor design are considered. On the other hand $I$–$V$ characteristic depends on the active layer (GO) bandgap energy in the metal/oxide/metal structure and therefore, needs to be explored. In the GO-based memristor, the bandgap energy can be changed by the percentage of the oxygen groups in comparison to the carbon on graphene sheets. Thus, the other parameters are overstated by the bandgap energy. In the presented work, the energy bandgap of a high epoxy group content of GO sheets is engineered. The opening of the bandgap in the graphene oxide by high epoxy groups content with the ratio of (O/C $=$ 50%) is studied. In other words, the oxygen adsorption effect on the Hamiltonian of the system is explored. For the proposed structure, the bandgap energy is modeled and the acceptable value (approximately equal to 2.799ev for epoxy groups) is obtained. Moreover, the hydroxyl group adsorption effect on the bandgap of the graphene oxide by high content hydroxyl group is considered (approximately equal to 2.647ev for epoxy groups). Consequently, the different absorption energy effects on the bandgap of the GO is participated and the opening bandgap in the range of 2ev to 3ev is obtained. The excitonic effect on the suggested model by epoxy groups and hydroxyl groups is explored and it is realized that the energy levels in the Dirac points of epoxy groups are closer than those of the hydroxyl groups.

The present work aims at numerical approximation in combination with experimental validation of some of the important performance measures in turning of commercially pure titanium (CP-Ti) with uncoated carbide inserts. A three-dimensional (3D) finite element model was developed based on Lagrangian criterion. Simulation of the turning operation was performed using DEFORM 3D software in order to approximate the responses viz. feed force ($F_x)$, radial force ($F_y)$, tangential force ($F_z)$, flank wear (Vb) and machining temperature ($T_m)$. Usui’s tool wear model was used to predict the flank wear. Morphology of the free and back surfaces of the chips was examined under a field emission electron microscope (FESEM). Turning experiments were carried out on a heavy duty lathe equipped with a 3D dynamometer. Secondly, a quadratic model was acquired for all the aforementioned quality characteristics using response surface methodology (RSM). Analysis of variance (ANOVA) test was performed to confirm the adequacy of the developed quadratic model. The results obtained from simulation and quadratic model were compared with the experimental data sets. Finally, an error analysis was done to determine the percentage inaccuracy of both the models. The percentage error for all the turning responses, was observed within 6% which showed the satisfactoriness of the proposed approximation tools. However, the simulation model exhibited lower prediction error when compared with the quadratic counterpart.