In countries where the earthquake has devastating effects, new buildings should be earthquake-resistant. For this, soil surveys and structure natural vibration frequencies should be considered. In this study, regardless of the ground period, the fluid damper has been modeled numerically to decrease the natural vibration frequency of the structure. In fluid dampers, mechanical energy is converted into heat energy. The fluid damper was exposed to the same structure frequency value during an earthquake of 10, 20, 30, 40, 50, and 60s for four different building heights (6–12–18–24m) and the temperature and velocity distribution of the fluid damper was examined with the help of the COMSOL multiphysics. The temperature changes in the fluid damper for the 6m high building that has the lowest structure natural vibration period (highest frequency) were observed to be the highest. It has been determined that during the vibration, fluid passes through the micro channel between the piston and the outer surface of the fluid damper and reaches high temperatures and velocities because of the viscous heating effect.

In this paper, the effect of shot blasting parameters such as time, pressure, and grit size were studied over the water contact angle of additively manufactured aluminum alloy (AlSi10Mg) surfaces. The Taguchi L9 orthogonal array was implied to set the correlations and interactions between the shot blasting parameters and water contact angle as output parameters. The analysis of variance establishes a good agreement with the results, revealing the time as the most significant parameter with a 41.98% contribution, followed by the pressure (41.57%) and grit size (16.43%). Further, the roughness measurements and scanning electron microscopy analysis of the shot-blasted surfaces validate the variations in the water contact angle.

Durability is a key factor to determine the service life of organic coating. The addition of nanomaterials can improve the mechanical properties and compactness of the organic coatings. As a kind of nanomaterial, g-C3N4 has lamellar structure and can be excited by visible light. At the same time, its cost is low. So it can be selected as a filler to prepare organic coating. The lamellar structure of g-C3N4 is favorable for its dispersion in organic coatings. Stearic acid is an environmentally friendly material with low surface energy. It can improve the hydrophobicity of the coating. In this research, porous g-C3N4 nanosheets were used as filler and stearic acid was used as surface modifier to prepare waterborne acrylic resin-based organic composite coating. The chemical reagent durability, electrochemical durability and mechanical properties of the composite coating were tested. At the same time, the photocatalytic degradation performance of the coating surface was also tested. The results showed that g-C3N4 as filler and stearic acid could effectively improve the durability of the waterborne acrylic resin coating. Meanwhile, the coating surface has obvious visible light-activated photocatalytic performance due to the addition of g-C3N4.

Welded structures, specifically their fusion and heat-affected zones, are majorly prone to embrittlement and enhanced corrosion due to the induced residual stresses resulting from the complexity of the heating and cooling cycles during welding. In this work, TIG welding of AISI 4140 alloy steel (chromium–molybdenum steel) was done using the filler wire ER80S-B2 (AWS A5.28) followed by post-weld heat treatment. A comparison of base metal, as-welded, and post-weld heat-treated samples is made based on residual stresses, corrosion resistance, and mechanical properties. Due to the presence of stresses and the formation of unstable martensitic structure, the as-welded samples depicted the highest corrosion rate (8.982 mpy) as compared to the post-weld heat-treated sample (5.707 mpy) which is closer to that of base metal (5.627 mpy). Post-weld heat treatment relieves the residual stresses which results in the enhancement of corrosion resistance. The tensile strength for the base metal, as-weld and PWHT samples come out to be 739, 763, and 744 MPa, respectively. Ductility, on the other hand, is restored by post-weld heat treatment which was compromised in the as-welded samples.

This study was carried out to improve the surface of the AA7075 alloy, which does not resist wear. Therefore Al–SiC composite layer on the surface of AA 7075 material was coated with Al+5vol.%SiC powders under 600°C and 100, 120, 140 MPa pressure by the hot pressing sintering method. The microstructure of the transition zone between the coating and the substrate material was analyzed by using optical microscopy (OM), energy dispersive X-ray spectroscopy (EDS), and scanning electron microscopy (SEM) techniques. In addition, XRD measurement and microhardness of the coating layer were obtained. Coating surface was also subject to linear reciprocating wear test and coefficient of friction (COF), wear volume, and mass loss were detected. The results have shown that micro-pores between Al and SiC powders reduced by increasing the pressing pressure. However, although there was a reduction in wear volume and mass loss, microhardness values dramatically increased. Wear test was modeled in ANSYS 2021 R2 package program depending on Archard’s law and numerical analysis was conducted. As a result of the experimental results and numerical analysis, the volume loss values occurring in the coating area were found to be compatible with each other.

Hydrogen has received widespread attention as a new clean energy in order to reduce the carbon emissions of fuel vehicles. This paper studies a tubular microreactor based on methanol steam reforming. Methanol and steam are mixed in proportion and the chemical reaction takes place in a porous catalytic bed. For heating purposes, hot gas from the burner penetrates the reactor bed through heating tubes. Energy is supplied through the heating tubes to drive the endothermic reaction system. The microreactor is enclosed in an insulated jacket. In this paper, parameters such as methanol conversion and hydrogen concentration are evaluated by considering microreactor materials, heating gas temperature and flow direction, heating tube distribution, pressure drop and reaction channel length. First of all, choosing a microreactor material with a smaller thermal conductivity can avoid excessive heat loss, and improve heat transfer performance. Increasing the heating gas temperature leads to an increase in the temperature of the reaction zone, thereby increasing the CH3OH conversion rate and H2 mass fraction. Changing the flow direction of the heating gas affects the reaction rate, but has little effect on the reaction result. Through the research on the distribution of the heating tubes, the results show that the hydrogen production rate is higher when the contact area between the heating tubes and the reaction zone is larger. Secondly, through the comparison of the data under different pressure drops, the best parameter P=50pa is obtained, and the CH3OH conversion rate is 80.6% at this time. Finally, increasing the length of the reaction channel can make the reaction more complete. For example, when the reaction channel length L=0.39m, the CH3OH conversion rate is as high as 83.7%.

In this work, palladium nanoparticles (Pd NPs) are synthesized by laser ablation in liquid (PLAL) with wavelength 532nm (second harmonic Nd:YAG laser) at different laser energies 360, 660, and 800mJ with 200 pulses and an electric coil is used to generate a magnetic field. The resulting nanosolution was deposited on the previously prepared PS. The morphological and structural properties of the prepared substrates (Pd NPs/PS) are calculated by X-ray diffraction (XRD) pattern, Atomic Force Microscope (AFM), and Transmission Electron Microscopy (TEM). Their results showed that with the increase in the energy of laser pulse, the average particle size was 30.73, 22.60, and 18.01nm. Optical properties of Photoluminescence (PL) spectra show decrease of energy band gap at 2.38, 2.43, and 2.47eV with an increase in the energy. The sensitivity of application samples Pd NPs/PS/Si gas sensors for NO2 and H2S gas was also investigated with respect to temperature variations. Pd NPs/PS/Si gas sensors have a maximum sensitivity of NO2 gas around 52.6% at 25∘C for sample prepared at energy 360mJ but the highest sensitivity of H2S gas was 31.2% at 25∘C for energy of 660mJ. The effects of the operating temperature on reaction and recovery durations for various laser ablation energies are also discussed.

In this work, Zinc Oxide (ZnO) thin films doped and undoped with Sn and Al were grown on ITO substrates by the sol–gel spin coating technique, where the Sn/Zn and Al/Zn atomic ratios were, respectively, 5% and 7% in the solution. SZO and AZO structures were examined using XRD, AFM, SEM, UV–vis spectroscopy, and photoluminescence (PL) to investigate the morphology, structural, and optical characteristics. According to XRD analysis, all of the produced films have a hexagonal wurtzite structure with a polycrystalline nature oriented along the (1 0 0) direction. The crystallite size was calculated using the well-known Scherrer’s formula and found to be in the range of 23–40 nm. Scanning Electron Microscopy (SEM) results revealed that Sn and Al low doping had an impact on the morphological surface of the films. The measurements from the UV-Visible Spectrophotometer (U–Vis) showed that undoped ZnO film has a high optical transparency in the visible region (over >83%), and then the optical band gap of thin films was calculated. PL is observed for ZnO thin films doped and undoped with Sn and Al.

The main objective of this study was to assemble by friction stir welding two dissimilar sheets made with AA5754 Al-Mg alloy and AA 1050 aluminum, which are intensely used in the automotive industry. The applied welding speed was 75mm/min with different tool rotational speeds (780, 1330 and 2440rpm). The mechanical properties and the microstructure of the welded joint were investigated by the tensile test, the three-point bending test, the microhardness measurements, the optical microscopy, scanning electron microscopy and energy dispersion spectrometry (EDS). The main zones were observed in the welded joint. Optimum mixing was achieved during the assembly process with a welding tool rotation speed of 2440rpm. It was determined that the microstructures formed had a significant effect on the hardness and tensile strength of welded dissimilar materials such as the precipitated phases in the nugget zone. The best result in terms of tensile strength was obtained at 780rpm with 80% performance.

Nowadays, there has been continuous development of metallic biomaterials to meet special needs in the manufacturing of biomedical implants, units and systems so as to function well in the required environment. Developed biomaterials which possess exceptional properties in terms of biocompatibility and biomechanical compatibility require precision processing and machining to obtain the desired dimensional tolerances. Electrical discharge machining (EDM) is the noncontact or nontraditional process of machining that suits the precision machining of biomaterials. In this work, an effort was made to optimize the EDM parameters during machining of titanium-based biomaterials Ti-6AL-4V, so that the multi-objective responses could be obtained. The response surface method was used in designing the experiment, while the grey relational method was used to analyze the effect of multiple objectives into a single unit. The electrical parameters that were considered in this study include peak current, gap voltage, pulse turn-on and duty cycle. These parameters were set within the acceptable limits of the equipment. Three responses were studied, which are tool wear rates (TWRs), material removal rate (MRR) and surface roughness (SR). Using the signal-to-noise ratio and ANOVA optimum tool/electrode wear rate (TWR) is obtained at 5×10−5g/min with process parameters Ip=6 A, Vg=30V, Ton=200μs, D=65%. Optimum values of material removal rate (MRR) are obtained as 0.01035g/min with process parameters Ip=6 A, Vg=60V, Ton=140μs, D=50%. Optimum SR is observed as 2.258μm with EDM process parameters Ip=6 A, Vg=90V, Ton=200μs, D=65%. Surface characteristics are verified with SEM micrographs. Whereas, grey relation analysis predicted the multi-objective optimum response characteristics. Based on the grey relation grade, experiment number 7 (Ip=6A, Vg=90V, Ton=200μs, D=65%) secured the first rank among the experiments/trails.

In this study, thin PbSe films were deposited on the Si(100) by ion beam sputtering aiming at forming photoconductive infrared detectors. PbSe photodetectors are then gained through thermal oxidation over different temperatures for sensitization. The effect of oxygen sensitization on the morphology, composition and structure of PbSe photodetectors is studied. It was found that during the sensitization, the PbSe thin film grains gradually refine the melting junction due to oxidation and recrystallization. The proportion of the film surface O/(PbSe) atoms increased significantly, while the Se/Pb atoms greatly decreased due to the increased gasification of SeO2. The noise signal for sensitized PbSe films decreased and the detection rates were improved. The sensitization process designed in this paper helps to improve the photoresponse function of PbSe films.

The aim of this in-vitro study was to evaluate the influence of Ag+-ion-coated conditions on the corrosion, tribocorrosion and antibacterial properties of Ti15Mo alloy. The mean wear volume losses of all test specimens after tribocorrosion test procedures were determined using a noncontact 3D profilometer. The specimens’ hardness, roughness values and microstructures were measured using the microhardness tester, surface profilometer, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The mean wear volume loss of 30-min Ag+-ion-coated Ti15Mo alloy was lower than the other specimens. In this study, correlations between the hardness, surface roughness and wear volume loss were found to be significant. The PVD coating process enhanced the antibacterial activity of Ti15Mo alloy owing mainly to the formation of silver film on the substrates.

This study aims to investigate experimentally and analytically the effects of different machining parameters such as cooling methods and cutting tool materials on surface roughness and chip thickness ratio for milling of AA7075-T6 aluminum alloy. The carbide and high-speed steel (HSS) end mills were used as cutting tools and the conventional, vapor, and compressed air were used as cooling methods in the experiments. The experiment conditions for compressed air at the cutting zone were 6 bar pressure and 30m/s speed flow rate. A mixture of boron oil and water (1/20 mixture ratio) was used as cutting fluid in conventional cooling. The study was carried out using three levels of feed rates (20, 40, 80mm/min), rotational speeds (780, 1330, 2440rpm), and a constant 2mm deep cut. As a result of the experiments, the surface roughness values increased with the increasing levels of feed rate. Besides surface roughness values decreased with increasing levels of the rotational speed. In addition, a better surface quality was obtained in milling processes by using carbide cutting tools compared to HSS tools. It was concluded that the most important parameter affecting the surface roughness and chip thickness ratio is feed rate and the rotational speed, respectively. Better surface roughness and chip thickness ratio were obtained from the vapor processing than the conventional and compressed air.

Hydroxyapatite (HA)-coated metallic substrates are commonly used for load-bearing orthopedic implants. In this work, Titanium grade 2 and Titanium grade 5 substrates were coated with hydroxyapatite and hydroxyapatite reinforced with 5% (by wt.) multiwalled carbon nanotubes (MCNT) separately using plasma spray coating. The wear behavior of these coated substrates was studied with the simulated body fluid (SBF) having a pH between 7.20 and 7.40. Fracture toughness and wear resistance of HA reinforced with 5% (by wt.) MCNT composite coating was found to be higher as compared to pure HA coating. This improvement is by virtue of inherent mechanical properties and the crack bridging effect offered by MCNT. The addition of MCNT also helped in restricting crack propagation in the coatings. As evident from SEM images, abrasive and adhesive wear mechanisms were observed which reduce greatly with the reinforcement of MCNT.

The implementation of the fused deposition modeling (FDM) technique in the production system is mainly due to its flexibility and ability to fabricate complex 3D prototypes and geometries. However, the mechanical strength of the printed parts needs to be investigated which was influenced by the process parameters such as layer thickness (LT), raster angle (RA), and Infill Density (ID). Therefore, these process parameters need to be optimized to attain better mechanical strength from the FDM printed parts. In this research, ePA-CF filament material was used to fabricate the specimens based on the selected process parameters such as LT (0.07, 0.14, and 0.20mm), RA (0∘, 45∘, and 90∘) and ID (50%, 75%, and 100%). The artificial neural network (ANN) method was implemented to determine the influential printing process parameters. Tensile, flexural, and impact tests were considered as the response parameters based on the various combination of the input parameters. It was concluded that the printing of nylon carbon parts using LT=0.14mm, ID=100%, RA=90∘ retains improved tensile strength of 66 MPa, flexural strength of 87MPa and impact strength of 12.5KJ/m2. Further, the propagation of cracks and the mode of failure were examined using SEM fractography. These observations substantiate that the selection of an optimal combination of FDM parameters assists in enhancing the mechanical strength of the printed nylon carbon parts.

In this study, the effect of shot peening duration on the fatigue life of galvanized and non-galvanized springs was investigated. As the shot peening duration increased, the fatigue life of the compression springs decreased due to several embrittlement mechanisms on the spring surface. The surface roughness almost linearly increased with increasing shot peening durations. The best fatigue life was obtained with shot peening durations of 10 and 20 min for non-galvanized and galvanized springs, respectively. The non-galvanized specimens exhibited better fatigue performance than galvanized springs. The main reason for the decrease in the fatigue performance of galvanized springs is hydrogen embrittlement behavior. Free hydrogen generated in the acid bath during the galvanizing process is entrapped between the surface and the zinc layer. As a result, the compression strain that reflects crack onset and propagation was adversely affected by hydrogen embrittlement behavior.

The structures, electronic and magnetic properties of the TM(isq)2 (isq=o-diiminobenzosemiquinonate) clusters have been investigated by using the PBE functional. The lengths of TM-N bonds of the TM(isq)2 clusters are as follows: 3d<5d<4d. According to the binding energies per atom of the TM(isq)2 clusters, the 5d TM(isq)2 clusters are more structurally stable than the corresponding 3d TM(isq)2 and 4d TM(isq)2 clusters except for the Lu(isq)2 and Hg(isq)2 clusters. According to the HOMO–LUMO gaps of the TM(isq)2 clusters, the 5d TM(isq)2 clusters are more kinetically stable than corresponding 3d TM(isq)2 and 4d TM(isq)2 clusters except for the Lu(isq)2 and W(isq)2 clusters. As for the TM(isq)2 clusters, the TM atoms lose a small amount of electrons within the scope of 0.375|e|∼1.755|e|. Maximum Mülliken spin densities (3.228|e|,0.963|e|,2.560|e| and 2.266|e|) of TM atoms of the TM(isq)2 clusters occur at Cr, Co, Mo and W.

In marine, aviation and railway transportation, dirt, corrosion, and wear lead to rapid failure of equipment, and organic coating is the main protective means. Epoxy (EP) coating is a widely used film-forming material in organic coating. We report a new modification method — fluorine modified silicon carbide (F–SiC) modified EP coating. The hydrophobicity, wear resistance and corrosion resistance of the EP coating were improved by grafting fluorinated organic compound (F–SiC) onto the surface of silicon carbide particles and adding it to the EP coating. When the content of F–SiC is 3 wt.%, compared with the EP coating without F–SiC, the contact angle between 3 wt.% F–SiC EP coating and water increases by 63%, and the friction coefficient decreases by 73%. The corrosion resistance of 3 wt.% F–SiC EP coating is about three orders of magnitude higher than that of the EP coating soaked for six days.

In the present scenario, electrochemical arc machining (ECAM) (hybrid of electric discharge erosion and electrochemical dissolution) is an evolving procedure for difficulty in machining the materials due to constraints of existing processes. This research aims to investigate the machinability of Ni55.7Ti alloy through electrochemical arc drilling using molybdenum electrode. Electrolyte concentration (ethanol with ethylene glycol and sodium chloride), supply voltage, and tool rotation are considered as the variable factors to evaluate the ECAM performance characteristics in drilling blind hole operation concerning overcut (OC), tool wear rate (TWR) and materials removal rate (MRR). Consequently, response surface methodology is implemented for predictive modeling of various performance characteristics. Finally, multi-objective optimization through desirability function approach (DFA) has produced a set of optimal parameters to improve the productivity along with the accuracy, which is the prime requirement for the industrial applicability of the ECAM process. Results demonstrated that supply voltage is the influential key factor for improvement of machining rate. Scanning electron microscope (SEM) photographs revealed the development of heat affected zone (HAZ), white layer, melted droplet, craters, re-solidified material, ridge-rich surface and voids as well as cavities around the end-boundary surfaces of a blind hole. Composition analysis through energy dispersive spectroscopy (EDS) indicated the oxygen content on the machined surface because electrolyte breakdown causes oxidation to take place at elevated temperatures across the machining zone. Moreover, carbide precipitation like TiC was found in the melting zone of the drilled hole, as revealed by X-ray diffraction (XRD) analyses, which has the affinity to reduce the SMA properties in HAZ.

This paper is devoted to the investigation of functionalized graphene nanoplatelets (FGNPs) samples. Synthesis of FGNPs was carried out through oxidative chlorophosphorylation (OxCh) reaction, i.e. reaction of graphite with PCl3 in the presence of oxygen under different conditions. For this, the reaction of graphite with PCl3 in the presence of oxygen was carried out separately both at a temperature of 65°C and at room temperature in a CCl4 medium and at a temperature of 65°C in a CCl4 medium. The FGNPs samples obtained by this method were named FGNPs1, FGNPs2, and FGNPs3, respectively. FGNPs1, FGNPs2, and FGNPs3 were investigated using Fourier Transform Infrared (FTIR) and ultraviolet–visible (UV–Visible) spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analysis methods. The results of FTIR spectroscopy showed that all FGNPs samples contain phosphonate groups. Based on the UV–Vis spectroscopy, the optical band gap of the samples was calculated and compared with pristine graphite. It has been established that the width of the optical bands of FGNPs1 (1.17eV), FGNPs2 (1.22eV), and FGNPs3 (1.24eV) is wider than that of the pristine graphite (1.04eV). Based on the XRD analysis, it was determined that the functionalization causes a change in the crystal lattice parameters of graphite. Based on the XRD analysis, it was determined that the functionalization causes a change in the crystal lattice parameters of graphite and FGNPs samples (number of graphene layers: FGNPs1=∼45; FGNPs2=∼42; FGNPs3=∼37) to consist of fewer graphene layers than graphite (∼120).