Surface Review and Letters

In this paper, graphene nanosheets were used to detect ammonia gas (NH${}_3)$. Graphene dispersion was drop cast on special ceramic substrate to fabricate the gas sensor. The measurements were based on measuring the resistance before and after the gas exposure. A considerable increase in the resistance after gas exposure was found. Resistance increased from 1.4k$\mathrm{\Omega }$ to 1.8k$\mathrm{\Omega }$ just in less than 3s. Recovery time is also determined at room temperature and it was 2h. The delay in recovery time was ascribed to the fact that desorption is slower than the adsorption. Response to ammonia gas is calculated and demonstrates a maximum response of 198.6% after about 5min.

In this paper, formation of defects/defect clusters in nickel nanowires (Ni-NWs) due to interaction of a 60 kilo-electron-volt (keV) beam of proton (H${}^{+})$ ions is studied. Ni-NWs are exposed to various fluencies of H${}^{+}$ ions ranging between $1.5\times 10^{15}$ and $1.5\times 10^{17}$ions/cm². The analysis of pristine and H${}^{+}$ ion-irradiated Ni-NWs samples is mainly done using transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques. Stopping range of ions in matter (SRIM) simulation software is employed to verify the production of defect clusters in Ni-NWs theoretically. Furthermore, insight of creation of defects in Ni-NWs due to interaction of low energy H${}^{+}$ ions in keV range is made using the theory of collision cascade effect. The study of defect clusters induced in Ni-NWs under H${}^{+}$ ions beam irradiation is essential for application of Ni-NW-based nanodevices in harsh environment containing plenty of H${}^{+}$ ions such as for use in spacecraft equipped for space missions.

The various levels (5%, 10% and 15%) of Cu-doped TiO₂ thin films were grown on the $n$-type silicon (Si) wafer by spin coating technique to obtain Al/(Cu:TiO${}_2)$/$n$-Si (MOS) capacitors. Both the real and imaginary components of complex dielectric (${\epsilon }^{\ast }={\epsilon }^{\prime }-j{\epsilon }^{\prime \prime })$, complex electric modulus ($M^{\ast }=M^{\prime }+j{M}^{\prime \prime })$, loss tangent (tan $\delta )$ and alternating electrical conductivity (${\sigma }_{\mathrm{\text{ac}}})$ of the obtained Al/(Cu:TiO${}_2)∕n$-Si (MOS) capacitors were studied by taking into account the effects of Cu-doping levels into TiO₂ viaimpedance spectroscopy method (ISM) in the wide range voltage ($\pm 5$V) and frequency (10kHz–1MHz). All the obtained dielectric parameters were obtained as strongly dependent on frequency, voltage and Cu doping level. The observed anomalous peak in the forward bias region both in the real and imaginary components of ${\epsilon }^{\ast }$, tan $\delta$, complex electric modulus ($M^{\ast })$ and ${\sigma }_{\mathrm{\text{ac}}}$ were attributed to the Cu:TiO₂ interlay er, series resistance ($R_s)$, surface states ($N_{\mathrm{\text{ss}}})$, interfacial/surface and dipole polarizations. The higher values of ${\epsilon }^{\prime }$ at low and intermediate frequencies implied that $N_{\mathrm{\text{ss}}}$ have enough time to follow external ac signal, and also dipoles respond to the applied field to reorient themselves. Consequently, the fabricated Al/(Cu:TiO${}_2)∕n$-Si can be successfully used as MOS capacitor or MOS-field-effect transistor (MOSFET) in the industrial applications in near future.

This paper describes about selective deposition of material for pattern generation. The process is carried out using masking technique and by deposition of constituent material of powder metallurgical (P/M) green compact tool at selected area of aluminium work surface in Electro Discharge Machining (EDM) process. The process is carried out to generate line pattern with a hard layer of tungsten and copper at the selected area. Thus, it can improve surface integrity of aluminium substrate while maintaining its overall lightness. P/M tool, positive polarity of tool and hydrocarbon dielectric are used to achieve appreciable amount of material transfer from tool to work surface. The average deviation of material deposition from predefined boundary line is evaluated as edge roughness of the pattern. Taguchi Design of Experiment is used to perform Analysis of Variance (ANOVA) and Overall Evaluation Criteria (OEC) for its parametric study. The surface roughness is obtained in the range of 4.7–10.55$\mu$m and edge roughness in the range of 36.49–56.82$\mu$m in various working conditions. However, surface roughness of 4.00$\mu$m and edge roughness of 21.47$\mu$m are achieved at the optimum condition.

The amorphous phase (AP) and nanocrystalline particle (NP)-reinforced composite coating was fabricated by laser cladding (LC) of the Ni45-WC mixed powders on the 304 stainless steel. An LC technique favored APs as well as NPs to be formed due to their rapid cooling and solidification characteristics, so the wear resistance of the Ni-base coating was improved. Microstructures and wear resistance of the fabricated composite coating were studied extensively. The test results showed that the microhardness and wear resistance of this LC coating were enhanced under the actions of NPs, APs and the ceramics. The study of the laser synthesis of NPs provided a theoretical basis for improving the LC technique.

A reinforced concrete frame with masonry wall infill, “framed-brick work”, is a composite basic structure demonstrated to be feasible and effective on account of in-plane smooth excitations. Numerous models have been proposed for simulation of the behavior of masonry infills. The act of utilizing infill walls has been under investigation as it has both positive and negative impacts on the behavior of the structure under horizontal load. An enormous number of experimental and diagnostic examinations have been embraced in the past to research the behavior of such frames. The paper has focused on the working principles and the fundamental highlights of a recently created retrofitted masonry infill frames (RMIF) with carbon fiber–reinforced polymer (CFRP) sheets of RMIF. The presence of CFRP retrofitted in infill frames changes the behavior of the structure under substantial loads. The behavior examination, for example, deflection, ductility and tensile strength, is investigated for clay brick and fly ash bricks examples. For approval reason, this investigation utilizes feed forward back propagation neural network (FFBN) procedure. The correlation between experimental and the predicted values demonstrated that while the mechanical properties can be predicted for each specimen up partly by a portion of these models with the exact outcome achieved as a minimum error.

The selection of appropriate drilling parameters is essential for improving productivity and part quality, therefore, this work mainly concentrates on the investigation of drilling time, burr height, burr thickness, roundness and surface roughness. The drilling experiments were carried out on Magnesium (Mg) AZ91 with High Speed Steel (HSS) tool using the Vertical Milling Machine (VMM). The parameters reckoned are spindle speed and feed rate. Artificial Neural Network (ANN) was concerned with the building of the model that will be used to forecast the responses following the consideration of Response Surface Methodology (RSM). Conventional method of modeling (RSM) yields poorer results which redirected the study with ANN. The Genetic Algorithm (GA)-based ANN has been reckoned for developing the model. With two nodes in the parameter layer and seven nodes in the response layer, six different networks were constructed using variety of nodes in the hidden layers which are 2–6–7, 2–7–7, 2–8–7, 2–6–6–7, 2–7–6–7 and 2–8–6–7. It is observed that the 2–8–7 network offers the best ANN model in predicting the various responses. The prediction results ensure the reliability of the ANN model to analyze the effect of drilling parameters over the various responses.

With the miniaturization of electronic products, the portability and the critical need of clean energy for environment have led to the development of lead-free electroceramics. In this work, lead-free dielectric ceramics of 0.94Na${}_{0.5}$Bi${}_{0.5}$TiO₃–0.06BaTiO₃ (NBT–0.06BT) are synthesized by wet solid-phase method. The effects of calcination temperature on phase structure, morphology, densification behavior and dielectric properties are investigated. The XRD results indicate that all samples demonstrate typical diffraction peaks of perovskite structure. The SEM and dielectric analytical results show that high-performance dielectric property of NBT–0.06BT ceramic with dense microstructure and appropriate grain size can be achieved when the calcination temperature is appropriate.

Nano-sized Ni–AlN thin films were prepared by pulse electrodeposition (PE) on A3 steel substrates. The microstructures, surface root-mean-square roughnesses, microhardness values, and corrosion performances of obtained nano-sized Ni–AlN thin films were investigated. Corrosion weight losses of Ni–AlN thin films were predicted by Backward propagation (BP) networks model. The results indicated that average diameters of Ni and AlN embedded in the films were evaluated to 57.9 and 29.2nm, respectively. Also, thin films were observed with uniform and compact surface structures, and Rq value was estimated to only 32.75nm.

A method of modifying calcium carbonate particles was investigated by coating sodium stearate or sodium oleate on the surface of calcium carbonate by wet method. The results of FTIR, activation and dispersion index, dispersity in kerosene, surface wettability tests and zeta potential tests show that sodium stearate or sodium oleate has successfully coated on the surfaces of calcium carbonate. The main factors were researched and the optimal parameters were obtained for the best modification effect. Compared with common rubber, the modified calcium carbonate added rubber has larger breaking tensile strength (more than 21%) and larger elongation at break (more than 16%). This research provides a feasible way of modifying calcium carbonate for its use as filler in organic matrix, reduces the cost and has a potential application in large-scale production of modified calcium carbonate.

In this study, the surface of AISI 430 stainless steel was alloyed with B₄C using the plasma transferred arc welding hardface coating method and the effect of Ti addition was examined. The microstructure of the resultant hardface coating layer was examined through X-ray diffraction (XRD) analyses by using the scanning electron microscopy (SEM). Abrasive wear resistance was analyzed by measuring mass loss according to the L${}_{16}$ orthogonal array using the Taguchi design method. The “smaller the better” principle of the Taguchi method was used in graphic evaluations. Additionally, the effect of wear test factors on mass loss was calculated in % by performing the analysis of variance. As a result, the austenite, martensite, M${}_{23}$(B,C)₆, M₇(B, C)₃, Ti (B,C), Fe₃(C,B), Fe₃C, Fe₂C and Ti (B,C) phases were detected in the coating layers. The effect of these phases on wear behavior was evaluated. In addition, the optimization of the parameters was obtained with response surface methodology (RSM) based on Taguchi orthogonal experimental design. The results given by the effect parameters required for the developed wear estimation are successful. As a result of the ANOVA analysis, the most effective parameters for wear resistance mass loss were determined as wear distance, applied load and abrasive, respectively. It was observed not to have any effect on wear mass loss of the samples. The most suitable parameter values for the lowest wear values were determined.

Combined plasma nitriding and surface texturing approach were conducted on 316 stainless steel to enhance the tribological performance. Five different surfaces (316 substrates, plasma-nitrided 316, surface-textured 316, plasma-nitrided surface-textured 316, and surface-textured plasma-nitrided 316) were investigated. The tribological behaviors were studied using a ball-on-disk rotary tribometer against counterparts of Si₃N₄ balls in the air and under oil lubrication conditions. The results were analyzed from the aspects of friction coefficient, mass loss, and surface morphology about the tested specimens. The results presented that the frictional properties of the surface of plasma-nitrided surface-textured 316 were optimal under both friction conditions. Under dry friction conditions, the influence of plasma nitriding on mass loss was greater than that of surface texturing. Under oil lubrication conditions, the influence of surface texturing on mass loss was greater than that of plasma nitriding, and the processing sequence of surface texturing and plasma nitriding had little effect on the mass loss. The better wear resistance of plasma-nitrided surface-textured 316 resulted from the following aspects: first, the nitriding layer improved the surface hardness of the material. Secondly, the surface texture can capture the debris under dry friction conditions and provide continuous lubrication under oil lubrication condition.

In this work, hydrothermal oxidation of electrodeposited zinc coatings is used to produce zinc oxide (ZnO) films. In the first step, zinc (Zn) coating is electrodeposited on indium tin oxide (ITO) coated glass substrate. The Zn films are then immersed in deionized water at $95^{\circ }$C. The exposure time of Zn coating in deionized water is varied from 1h to 24h in sequence. At the 24h exposure time, X-ray diffraction (XRD) patterns reveal that zinc film has been completely converted to ZnO. Scanning electron microscope (SEM) results show morphological changes from flakes (for pure Zn) or 2D plates to rod (ZnO) like morphology which further changes to cotton-flower like shapes with an increase in oxidation time. Diffuse reflectance spectral measurements show the band gap tuning with oxidation time (it decreases from 3.28eV to 3.19eV). Photoluminescence (PL) spectra have depicted phonon replicas with energy separation of $\sim 124$meV for the ZnO films obtained after 6 and 12h exposure time in deionized water at $95^{\circ }$C temperature.

The need of engineered materials with high strength to weight ratio was instrumental for the development of a novel magnesium metal–metal composite with the addition of titanium (reinforcement) and aluminum (alloying element) through disintegrated melt deposition technique. The X-ray diffraction analysis and scanning electron microscopy analysis used to explore the metallurgical insights of the developed magnesium metal–metal composite. Wear tests were carried out with pin-on-disc equipment by varying the input parameters load and sliding velocity over a sliding distance of 2000m. Wear was obtained as the output from the experiments, and the same was analyzed through Pareto analysis of variance, to identify the significant parameters. Also, a fuzzy logic-based model was developed to predict the wear behavior of the metal–metal composite. The wear mechanisms involved in the dry sliding wear behavior were analyzed through worn surface analysis and wear debris analysis.

In this work, SiC/Ta_xC bilayer coatings were prepared on stainless steel surface by double glow plasma surface alloying technique to improve the wear and corrosion resistance of the substrate. The effect of reaction temperature during the growth of SiC on the microstructure and property of the coating was investigated. The results showed that the surface topography of the coating could be regulated by the reaction temperature during the growth of SiC. Interactional flower-shaped rings, reticulate patterns, nanoparticles and microparticles were observed on the samples prepared at 750^∘C, 800^∘C, 850^∘C and 900^∘C, respectively. Tribological performance tests showed that the friction coefficient and specific wear rate of all the coated specimens were significantly decreased than the uncoated ones, indicating that the wear resistance of stainless steel was improved by the SiC/Ta_xC coating. The construction of the bilayer coating enhanced the corrosion resistance of stainless steel in terms of electrochemical tests. With an increase of the reaction temperature, the wear and corrosion resistance increased at first and then gradually decreased. SiC/Ta_xC coating prepared at 800^∘C exhibited the best overall performance.