Sharif Digital Repository

Hot isotherm compression tests were performed in temperature range of 350-500 °C and at strain rates of 0.0005 to 0.5 s-1 for Al6061 alloy reinforced with alumina nanoparticles. Effect of deformation parameters and optimal conditions for hot working this nanocomposite were comprehended thoroughly via hot working data analyses, electron microscopy images, and X-ray diffractograms. The results indicated the severity of hot deformation process and an increase in the activation energy to 320 kJ/mol due to the addition of nanoparticles. Dynamic recovery (DRV) was considered as the individual determinative softening mechanism during hot deformation of this nanocomposite, and no sign of dynamic... 

Herein, we demonstrate a new fabrication strategy for low-cost and stable-operation perovskite solar cells (PSCs) suitable for commercialization. This is performed by fabrication of the device under ambient conditions using a Cs0.05(MA0.17FA0.83)0.95Pb(Br0.17I0.83)3 formulation as the mixed cation and halide (MCH) perovskite and CuInS2 (CIS) as the inorganic hole transporting layer. The deposited MCH perovskite with uniform, compact and smooth microstructure containing equiaxed large grains showed excellent thermal and structural stability under intense conditions at 85 °C for 2 h in humid air (i.e., 45% relative humidity). Moreover, it had higher phosphorescence emission, absorption and... 

Creating laser texture on dental implants is a novel method for accelerating osseointegration and prolongation of lifespan. The purpose of this research was twofold: (1) Creating intersecting lines pattern with different angles (0°, 15°, 30°, 45°, 60°, 75°, and 90°) on the surface of Ti6Al4V, using pulse Nd:YAG laser with a wavelength of 1064 nm and a pulse length of 170 ns and (2) comparing optical and SEM images, EDS analyses, contact angles (CAs), and surface free energies (FEs) for different intersecting lines angles. CA and FE depended on the intersecting lines angle according to Y = Y 0 + A sin (x B + C), where Y is the CA or FE; x is the intersecting lines angle; and Y0, A, B, and C... 

Automatic image annotation is a challenging problem in the field of image retrieval. Dealing with large databases makes the annotation problem more difficult and therefore an effective approach is needed to manage such databases. In this work, an annotation system has been developed which considers images in separate categories and constructs a profiling model for each category. To describe an image, we propose a new feature extraction method based on color and texture information that describes image content using discrete distribution signatures. Image signatures of one category are partitioned using spectral clustering and a prototype is determined for each cluster by solving an... 

Despite the great use of concrete, tensile strength and low flexibility and brittleness are its weaknesses. Many solutions have been provided to eliminate the mentioned defects. In order to increase the flexibility of concrete in previous studies, crushed rubber tire particles have been added to concrete. Recycling car tires helps the environment and makes concrete much more flexible than regular concrete. In this research, silicone rubber has been replaced by 0%, 2%, 4%, 8%, 12.5%, 25%, and 50% of mineral aggregates. This rubber was initially in liquid form, which, after mixing with ordinary concrete, dispersed into the concrete texture and formed a uniform mixture, and this liquid rubber... 

The fabrication of Ni/Ti laminated composite via cross accumulative roll bonding (CARB) and subsequent annealing treatment has been studied. The relationships between annealing conditions and microstructure at interfaces of Ni/Ti have been investigated by SEM, XRD, and EDS analyses. The results show that the layers were well-bonded by the CARB process, and by increasing the temperature and time of annealing treatment, the interfacial layers grew as a result of the interdiffusion of Ni and Ti atoms. The main intermetallic phases were NiTi and NiTi2, both of which obeyed linear kinetics of growth. However, the calculated activation energy of NiTi was lower than that of NiTi2, indicating the... 

The presence of nodules on the surface of cathode copper plates was the most important reason for the failure of the punch of mechanical clinching of copper cathode sheets. This study demonstrated a comprehensive investigation into the nodulation growth of copper cathodes in the electrorefining plant based on metallographic analysis. More than 15 random samples were selected from the top, middle, and bottom of the cathodes produced in the Khatoon Abad copper refinery, Iran. Studies were carried out based on the determination of growth modes including field oriented isolated crystal (FT), basis-oriented reproduction (BR), field-oriented texture (FT), and unoriented dispersion (UD). A scanning... 

This paper is presenting the data on interactions between Fiber laser and shale. With this obvious goal that is dependent on improving the efficiency of laser power. The idea of selecting shale sample was because of variety of this rock type in Iranian oil and gas formations. In the experiment, a long pulsed laser beam was arranged to drill and propagate surfaces, in the opposite direction to the earth gravity, and it was used to drill hole from the top to the bottom of cylindrical Shale rock. The heat that been induced from the Fiber laser is absorbed in the direct surfaces in front and cause heat flux generation inside of rock texture. The specific heat transfer inside of shale sample can... 

Identification of different flow regimes in industrial systems operating under two-phase flow conditions is necessary in order to safely design and optimize their performance. In the present work, experiments on two-phase flow have been performed in a large scale test facility with the length of 6 m and diameter of 5 cm. Four main flow regimes have been observed in vertical air-water two-phase flow at moderate superficial velocities of gas and water namely: Bubbly, Slug, Churn, and Annular. An image processing technique was used to extract information from each picture. This information includes the number of bubbles or objects, area, perimeter, as well as the height and width of objects... 

In this study, Ni-Fe/SiC nanocomposite coatings with smooth and crack-free surface were successfully prepared by means of the conventional electrodeposition in the presence of saccharin in electrolyte. The goal of this work was to investigate the effect of SiC nanoparticles and saccharin on the structure and properties of permalloy nanocomposite coatings. The nanocomposite coatings were characterized using optical and scanning electron microscopy, energy dispersive X-ray (EDX) analysis and X-ray diffraction (XRD) technique. The significant variation in the crystallographic texture of the coatings was observed due to the addition of SiC nanoparticles and saccharin in the electrodeposition... 

Owing to the advantages of nanocomposites for structural applications, we present microstructural evolutions and texture development during dissimilar friction stir welding (DFSW) of an Al-matrix hybrid nanocomposite (Al-2 vol.-% Al2O3-2 vol.-% SiC) with AA1050. It is shown that DFSW can successfully be performed at a rotating speed of 1200 rev min−1 and a transverse speed of 50 mm min−1 while locating the nanocomposite at retreating side. Formation of macro-, micro-, and nano-mechanical interlocks between dissimilar base materials (BMs) as a result of FSW tool stirring action possessed an impact influence on the mechanical performance of dissimilar welds. Electron microscopy revealed... 

Owing to the advantages of nanocomposites for structural applications, we present microstructural evolutions and texture development during dissimilar friction stir welding (DFSW) of an Al-matrix hybrid nanocomposite (Al-2 vol.-% Al2O3-2 vol.-% SiC) with AA1050. It is shown that DFSW can successfully be performed at a rotating speed of 1200 rev min−1 and a transverse speed of 50 mm min−1 while locating the nanocomposite at retreating side. Formation of macro-, micro-, and nano-mechanical interlocks between dissimilar base materials (BMs) as a result of FSW tool stirring action possessed an impact influence on the mechanical performance of dissimilar welds. Electron microscopy revealed... 

The newly developed multiphase transformation-induced plasticity (TRIP) steels are of interest for industrial applications because of their excellent combination of high strength and ductility. Their performance can be successfully controlled by designing an optimum balance in the volume fractions of ferrite, bainite and retained austenite. The characteristics of the retained austenite are considered to be the main key to achieving the desired final properties. Against this background, the effects of retained austenite characteristics, such as volume fraction, carbon concentration, size and shape, on the behaviour of TRIP steels have been studied. The crystallographic orientation of the... 

The influence of annealing treatment on macro- and micro-texture of cold-rolled FeCo-7.15V ferro-magnetic ultra-thin foils were studied. The microstructural studies performed by field emission scanning electron microscope (FE-SEM) showed the formation of paramagnetic precipitations ((Fe, Co)3V) during annealing. During cold rolling of the FeCo-7.15V magnet, the texture components of type (113)[110], (001)[110], (111)[110], and (111)[121], all related to α and γ-fibers were formed. X-ray diffraction (XRD) and local texture measurements performed by electron backscatter diffraction (EBSD) were made on the annealed samples. Both methods revealed that the recrystallized samples have texture... 

The texture, microstructure, and mechanical properties of severely deformed aluminum subjected to friction stir processing (FSP) with SiC nanoparticles under ambient and cryogenic temperatures are comprehensively investigated. Even one pass of FSP in the ambient temperature results in the formation of quite large grain structure with random texture in the heat affected zone (HAZ). It suggests the occurrence of static recrystallization and subsequent grain growth because of the appreciable strain stored within the base metal. One FSP pass under condition of cryogenic temperature causes to the development of bimodal grain size distribution in HAZ, including the elongated grains with interior... 

In this research, the effect of different amounts of Cr2O3 (2.5, 5, 7.5, and 10 wt.%) and sintering temperature (1850, 1900, and 1950 °C) on the sinterability and mechanical properties of liquid-phase sintered SiC-matrix composites was studied. First, raw materials were ground for 3 h using a planetary mill whose rotational speed was 180 rpm. The process of pressing the samples was completed using uniaxial pressing with the applied pressure of 90 MPa. Finally, the samples were sintered under an argon atmosphere at various temperatures for 1.5 h. In the end, the best sintered sample was annealed at 2000°C for 2 h. The phases, microstructure, and chemical composition of the samples were... 

Effects of microstructure and texture, before and after phase transformation, on the anisotropy of the mechanical properties and fracture behaviors of commercially pure titanium were studied. Before phase transformation, due to the split distribution of basal texture the activation of different deformation systems led to mechanical properties anisotropy. Although the fracture mechanism in both specimens was voids nucleation, growth and coalescence, the shape, size and distribution of dimples were affected by active deformation systems. However, after phase transformation, basal plains in most grains were aligned with the transverse direction. This texture component led to the activation and... 

In this study, we investigate the limitations and influence of various factors on the performance of trolling mode atomic force microscopy (TR-AFM). For this purpose, at first, based on the governing equations of motion and using a conventional control method, a simulation tool capable of correctly simulating the imaging procedure in TR-AFM is developed. Then based on the developed simulation tool, imaging of different surfaces is performed, and the effect of different factors on the image quality is analyzed. The flexibility of nanoneedle in TR-AFM has unpredictable effects on dynamics of system as well as imaging performance. One problem in imaging is due to coexistence of two stable... 

Fabrication of high quality zinc oxide thin films and analysis on its physical, chemical properties have applications in opto-electronic devices, UV laser, microelectronics and micro-machining schemes. Highly textured ZnO thin film with a preferred (0 0 2) orientation was prepared by two-stage chemical deposition (TSCD) using an aqueous solution containing zinc complex on a soda-lime glass substrate. From the results obtained, it can be shown that the preferred orientations of the film microcrystal changes with the doping process. The film was characterized by X-ray diffraction (XRD), SEM, EDAX, optical technique, Fourier transform infrared spectroscopy (FTIR) in order to qualify its... 

This study investigated the synthesis of Pd nanoparticles (NPs) using a high-gravity technique mediated by Salvia hispanica leaf extracts. Biological assays confirmed their antibacterial activity against gram positive (S. aureus) and gram negative (E. coli) bacteria with significant antioxidant activity in comparison with the standards as well as low cellular toxicity on PC12 and HEK293 cell lines. To the best of our knowledge, this study can be considered as the first investigation of Pd-NPs synthesized by Salvia hispanica leaf extracts assisted by a high-gravity technique. In addition, the mentioned green synthesis procedure led to the formation of nanoparticles with considerable...