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The main aim of this research is to analyze the mechanical performances of the influence of silicon carbide (SiC) particles with AA6351 aluminum alloy. The aluminum metal matrix composites were prepared with liquefying stir casting to produce the metal matrix composites (MMCs). The following weight fractions are AA6351-0% SiC, AA6351-2.5% SiC, AA6351-5% SiC, and AA6351-7.5% SiC utilized to compose the MMCs. The mechanical performances like hardness, flexural, impact, compressive, and tensile studies were investigated on the processed MMCs. The scanning electron microscope (SEM) was employed to examine the strengthened particle of SiC. During the SEM examinations, uniformly dispersed SiC-strengthened particles were analyzed. The entire MMCs specimens achieve greater mechanical characteristics; the specimen fabricated with a maximum volume fraction of 7.5 wt% of SiC accumulates higher strength than the other volume fractions samples. The SiC plays a very tedious role in improving mechanical attributes. The fabricated MMCs were highly utilized in the applications of automotive and aerospace usages. This application is fully employed with lesser weight and maximum strength conditions to fulfill the mechanical performances. The stir-casting process was a highly efficient technique to compose better MMCs to achieve greater strength. [ABSTRACT FROM AUTHOR]

In this study, a bottom pouring-type stir casting machine was used to create AZ31 magnesium alloy hybrid nanocomposites with varying weight percentages (0, 3, 5, and 7) of silicon carbide (SiC) and graphite (Gr) particles. Investigations have been made into the mechanical characteristics and microstructural distribution of manufactured hybrid nanocomposites. The outcomes demonstrate that the mechanical characteristics and uniform distribution of SiC and Gr particles are enhanced compared to those of the base alloy. In comparison to monolithic AZ31 alloy, microhardness, ultimate tensile strength (UTS), yield strength (YS), and compressive strength (CS) were raised by about 54%, 68%, 82%, and 107%, respectively. The presence of reinforced particles, the uniform distribution of particles, and the strong interfacial connection between the matrix and reinforcement all contribute to the improvement of mechanical properties. However, the addition of 7 wt. % SiC/Gr showed good mechanical properties compared to the base alloy. The microstructure of nanocomposites was analyzed using a scanning electron microscope (SEM), and particles were described using energy-dispersive spectroscopy (EDS). [ABSTRACT FROM AUTHOR]

In order to determine the effect of graphene oxide (GO) on the physical property and microstructure of the asphalt binder, GO material was selected to prepare GO-modified asphalt for analysis. Firstly, the surface/interface characterization and chemical analysis were performed on GO and GO-modified asphalt. The physical properties of GO-modified asphalt were investigated through softening point, ductility, and penetration tests. The impact of GO material on the rheological behavior of asphalt was characterized by Brookfield viscosity and dynamic shear rheological tests (DSR). Furthermore, the typical microstructure of GO inside asphalt material was also identified and analyzed through a scanning electron microscope (SEM) and transmission electron microscope (TEM). The results showed that the modifying effect of GO materials could promote the fusion between asphalt and GO. A modified GO could improve the high temperature of asphalt, but it would degrade the low temperature property of the asphalt binder. A modified GO could be integrated with asphalt and achieve a modifying effect on the asphalt material. This study would provide references for the application of graphene oxide in asphalt pavement materials. [ABSTRACT FROM AUTHOR]

The variation of soil structure and mechanical damage caused by freeze-thaw cycles results in degradation of engineering properties and engineering geological problems, such as deformation, cracking, and even project accidents. In this study, the freeze-thaw cycle tests, unconfined compressive strength tests, scanning electron microscope (SEM) tests, and nuclear magnetic resonance (NMR) tests were carried out to find out the effects of freeze-thaw cycles on the mechanical behaviors and microstructure properties of Tianjin Binhai cohesive soil. The results show that the original structure of the cohesive soil has been destroyed after the first freeze-thaw cycle, resulting in severe loss of compressive strength by 84.2%. The axial stress-strain response showed a strain-hardening behavior transitioned to a strain-softening behavior after 15 freeze-thaw cycles. The unconfined compressive pressure, sensitivity, and void ratio showed the same corresponding reaction with the increase of freeze-thaw cycles. The effects of freezing and thawing on void ratio were weakening with the increase of consolidation pressure, since the void expansion and contraction were limited with smaller void sizes. The frost-heaving force during the freezing process increased the compaction of the soil structure, and face to face contact became the main contact formation, which led to a reduction in void ratio. This study provides technical guidance for evaluation on the mechanical properties and engineering stability of cohesive soil in seasonally frozen areas and technical support for artificial ground freezing treatment on underground construction of the west coast of Bohai Bay. [ABSTRACT FROM AUTHOR]

Laser cladding is a repair and surface-strengthening technology for the protection of metal parts. It is an effective method for improving the properties of various metal substrates. The process involves melting and solidifying alloy powder on the surface of the substrate. The aim of the present study was to explore the effect of iron-based alloy laser cladding coating on Q235 substrate. Three types of specimens were obtained from Q235 base material using a 5 kW cross-flow CO2 laser beam. Sample 1 and sample 2 were obtained by the addition of rosin to the iron-based alloy powder. Sample 3 was obtained through the addition of rosin and vanadium to the iron-based alloy powder. A gas curtain was used to wrap the molten pool of samples 2 and 3. The surface hardness of the specimens was determined using a Rockwell hardness tester, and the tensile strength was evaluated using the universal mechanical testing machine. The microstructure of the cladding coating was explored using an Olympus optical microscope and SEM. The results showed that the average hardness of sample 2 and sample 3 was 6.42% and 19.84% higher than that of sample 1. The average tensile strength of samples 2 and 3 was 7.42% and 10.37% higher than that of sample 1. The grain of sample 3 was finer than that of sample 2, and that of sample 2 was finer than that of sample 1 under the same magnification. Rosin minimized oxidation of the substrate, whereas the gas curtain prevented the entry of air into the molten pool, hence the improved properties of samples 2 and 3 compared with that of sample 1. Rosin and the gas curtain protected the powder from oxidation loss and improved the quality of the cladding coating. The results of the present study show that rosin reduced the oxidation of iron-based powder, whereas vanadium improved the hardness and strength of the substrate as well as refined the grain size. [ABSTRACT FROM AUTHOR]

The aim of this study is to evaluate the wear and micro hardness of a Ti-6Al-4V matrix reinforced with 10% and 15% tungsten carbide particle (WCp) composite manufactured using the squeeze casting process. Optical microscopy is used to determine the microstructures of the composite. A pin-on-disc wear test equipment and Vickers hardness at atmospheric temperature were used to examine the wear behaviour wear rate, CoF, and micro hardness qualities of primed samples. Loads of 10 N to 80 N, velocities of 4 m/s, and distances of 1000 m to 2000 m are considered for analyzing the wear behaviour of Ti-6Al-4V composites. The wear rate values are 25.683 for 10% WCp, 30.957 for 15% WCp, and 37.683 and 30.957 for 20% WCp. A scanning electron microscope (SEM) is utilized to examine the worn surface of the composites. For 10% WCp, the CoF values are 0.82 and 0.87, and for 15% WC, 0.88 and 0.956. The micro hardness values are 692 VHN for 10% WCp and 835 VHN for 15% WCp. The wear rate, microstructure, SEM images, coefficient of friction, and hardness of TMCs for totaling reinforcing tungsten carbide particle (WCp) possessions were discovered to be improved. [ABSTRACT FROM AUTHOR]

This article focuses on the microstructure and mechanism analysis of the novel coating MgO– B2O3–SiO2–Zn prepared by plasma spraying and flame spraying on the SUS304 alloy substrate. Firstly, the crystal compositions of the powders were analyzed by XRD (X-ray diffraction). Secondly, the surface and cross section microstructures of the coating were observed by SEM (Scanning Electron Microscope) and EPMA (electron probe microanalysis) in order to study the mechanism of the thermal insulation performance. It is concluded that, the microstructure, different thickness and compositions have various effect on heat insulation. [ABSTRACT FROM AUTHOR]

In order to investigate the effect of nano polymer materials on the UV aged performance of asphalt binder, a nano PA modifying agent was selected to prepare modified asphalt. Under the effect of UV radiation, the modifying effect of nano PA on the rheological properties of asphalt was studied. With the extension of UV ageing time, the microstructure variation of PA modified asphalt was characterized by using a focused ion beam scanning electron microscope (FIB-SEM). The thermophysical properties of PA modified asphalt were investigated by thermogravimetric analysis (TG). Furthermore, the functional group compositions of PA modified asphalt were investigated by dynamic FTIR. The results showed that with the extension of UV ageing time, the PA modifier could mitigate the ageing effect of UV radiation on the asphalt binder. PA modifier could achieve an increasing effect on the viscoelasticity of asphalt during the UV ageing process. PA modifier suppressed the generation of microcracks in the surface microzone of UV aged asphalt samples. PA modifier could promote the thermal stability improvement of asphalt binder when subjected to UV radiation. The generation of carbonyl and sulfoxide groups in asphalt was inhibited during the UV ageing period, which indicated that the UV induced reaction of asphalt could be postponed by the PA modifying agent. [ABSTRACT FROM AUTHOR]

Povidone iodine (PVP‐I) is widely used as an efficient antiseptic disinfectant, which can kill various pernicious microbe. PVP‐I also exhibits certain toxic effects to the environment. To study the comprehensive toxic effects of PVP‐I on microalgae, different concentrations including 0, 7, 14, 28, 56 and 112 mg/L were set. The effects of PVP‐I on the growth performance, microstructure, photosynthesis, antioxidant levels and photosynthesis associated genes expressions of microalgae were investigated. The results showed that PVP‐I had significant effects on the growth and physiological functions of C. pyrenoidosa. Under the observation of scanning electron microscope, PVP‐I of 56 and 112 mg/L could destroy the cytoderm of C. pyrenoidosa directly. Under the PVP‐I exposure, the activity of SOD and CAT fluctuated up and down, while MDA content continued to rise. The relative gene expression of PsbA gene was significantly up‐regulated in high concentration of 112 mg/L PVP‐I. The relative gene expression of rbcL and rbcS gene were upregulated in 28 mg/L PVP‐I. The results of present study showed that PVP‐I could induce the production of oxidative stress response in C. pyrenoidosa, inhibit the expression of genes related to photosynthesis of C. pyrenoidosa and affect the photosynthesis of C. pyrenoidosa. The present study will provide a reference for the safe application of PVP‐I. [ABSTRACT FROM AUTHOR]

The effect of extrusion ratio and addition of glass and fly ash on microstructural, mechanical properties, and fracture behavior of Al composites is examined. Both the composites and hybrid composites are prepared by the liquid metallurgical technique. Microstructure, extrusion effect on hardness, tensile properties, and fracture are studied using an optical micrograph, hardness tester, Universal Testing Machine, and scanning electron microscope, respectively. Experimental results show that increasing the extrusion ratio leads to a significant enhancement in mechanical properties such as tensile, compression, and yield strength and Young's modulus, but results in a small reduction of ductility. It has been revealed that the presence of glass and fly ash improve the mechanical properties significantly with a slight reduction in ductility compared to the Al alloy. Fracture behaviour of the base alloy and composites show intergranular ductile and brittle cleavage mode failure as observed by SEM. [ABSTRACT FROM AUTHOR]

Microstructural evolutions of EK61 superalloy during long-term aging until 1000 h at 700°C and 750°C, respectively, are studied by combination of Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). Impact fracture morphologies after aging for different time are observed by the SEM. The microstructure is found to be relatively stable during aging at 700°C, and the fracture morphologies are characterized by transgranular fracture. At 750°C, the coarsening of γ ′ phase leads the reduction of the quantity of dimples, the chainization of carbides on grain boundaries leads to intergranular fracture, and the netting of η phases within grains leads to the formation of lamellar cleavage steps. It is obvious that the destabilization of precipitated phases affects fracture morphology significantly. The relationship between fracture morphology and the microstructure promotes the evaluation of service reliability of EK61 superalloy. [ABSTRACT FROM AUTHOR]

Soil-water characteristic curve (SWCC) is a key constitutive relationship for studying unsaturated soil, and as is known, microstructure of the soil has great influence on the mechanical behaviour of the soil. In this study, the wetting and drying soil-water characteristic curves (SWCCs) of loess compacted at three different water contents were measured using the filter paper method. And microproperties of compacted loess were obtained by the mercury intrusion method (MIP) and scanning electron microscope (SEM). Results show that the compaction water contents have significant influence on the SWCC and microstructure. The pore size distribution (PSD) curves have great differences in macropore range and are similar in micropore range. Loess compacted at optimum and dry of optimum are generally connected, while there are certain number of nonintruded pores in loess compacted at wet of optimum. The SWCC curves vary significantly in low suction ( u a − u w < 1000 kPa) and tend to converge together in high suction ( u a − u w ≥ 1000 kPa). Hysteresis in the SWCCs is more obvious for loess compacted at optimum and dry of optimum in the matric suction of 0∼100 kPa; however, there is a pronounced hysteresis for loess compacted at wet of optimum in full matric suction range. The characteristic of the SWCCs including their hysteresis can be well interpreted from the loess microstructure. [ABSTRACT FROM AUTHOR]

In this study, magnesium alloy AZ91, which was cast by double roll casting system, was rolled by a rolling mill. Then, rolled magnesium alloy and magnesium alloy without being rolled were, respectively, welded with aluminum alloy 6061 by diffusion bonding method. Furthermore, annealing process was applied to refine the microstructure and improve mechanical property. The microstructure and elemental distribution of diffusion zone were investigated with a scanning electron microscope (SEM), an electron probe micro analyzer (EPMA), and a transmission electron microscope (TEM). In addition, hardness and tensile strength were measured. When cast magnesium alloy was used, the width of diffusion layers was wider than that with rolled magnesium alloy. And the width increased with the increasing annealing temperatures. Element distribution of specimens with annealing was more uniform than that did not undergo annealing process. Furthermore, tensile strength turns to be strongest after annealing at 250°C. And the strength of the specimens with rolled magnesium alloy was stronger than that with cast magnesium alloy which was not rolled. [ABSTRACT FROM AUTHOR]

This paper presents the results of an evaluation study of gas drainability in the Bulli seam in the Southern Coalfield of the Sydney Basin, NSW, Australia, where the coal seam gas (CSG) contains a high proportion of carbon dioxide (CO2). Historically the gas drainability in some particular areas of this coal seam was found to be particularly poor, which posed a significant challenge to gas predrainage. As a result, a large volume of greenhouse gases were released to the atmosphere during mining of the coal seam. Furthermore, the high gas content associated with the CO2-rich composition also increased the risks of coal and gas outburst incidents, affecting the safety of mining. After systematic literature review of evaluation factors affecting gas drainability, this evaluation study comprehensively analyzed the main critical factors, including the geology of the area, the coal cleat system, coal microstructure, coal permeability, coal sorption capacity, gas content, and gas composition. Field geology analysis showed geological variations that affected the variations of the coal cleat system and CO2 content in the coal seam. Scanning Electron Microscope (SEM) tests showed the tight and less-porous features in hard-to-drain coal samples. The colliery gas database analysis was carried out to assess the impact of gas content and gas composition on the drainability of the coal seam. Laboratory tests showed that the coal seam had a permeability of less than 1 mD and also showed that the coal seam was highly undersaturated, especially with high CO2 content. [ABSTRACT FROM AUTHOR]

The influence of the microalloying elements of 34CrNiMo6 steel on the microstructure and mechanical properties is investigated in this paper, especially Al and N. Then, the testing of the tensile strength, yield strength, elongation after breakage, and impact absorbing energy under the different conditions is carried out to compare the mechanical properties of materials. Based on the experimental results, the evolutions of mechanical properties with the content of aluminum are obtained. The average grain size test and scanning electron microscope results illustrate that the strengthening mechanism is the pinning effect of aluminum nitride. [ABSTRACT FROM AUTHOR]

The effect of microstructure on macroproperties of building materials was the initiation in order to use microscopic techniques for studying the materials’ behavior. Primer role among the different techniques has the scanning electron microscope (SEM) as it provides much information in an easy and understandable way. SEM has been used in almost every study of the last decades, dealing with historic and repair materials to complete the analysis performed. In the case of historic mortars, it is a unique technique as it requires a small representative sample and without any intense treatment important information derived from an almost unknown sample including damage detection, phase identification, and microanalysis. It is usually a complementary method of analysis but a precious one as the gained results from the analysis of old mortars are used for designing compatible repair materials for restoration purposes. In the paper, the long-term use of SEM in studying both old authentic and innovative repair mortars is presented. [ABSTRACT FROM AUTHOR]

In order to reveal the water-induced damage mechanism and mechanical properties of red-layers in Southern China, typical red-layer samples are experimentally studied by scanning electron microscope (SEM), energy spectrum analysis, XRD, and mechanical tests. The results show that some red-layer samples contain a large number of smectite and illite-smectite mixed-layer clay minerals and their microstructures are mainly stacked microaggregates in which mutual agglomeration is formed by flake and tabular clay particles. Widespread distribution micropores and fractures in microaggregates provide the necessary moisture migration channels. The various cemented materials produce a kind of irreversible structural strength, and this strength is vulnerable for the aqueous medium conditions. The influence of microstructures and mineral compositions on red-layer mechanical properties is discussed. The results could provide the reference for further research about the water-induced damage mechanism of red-layers in Southern China. [ABSTRACT FROM AUTHOR]

The effects of ball milling on the hydrogen sorption kinetics and microstructure of Zr0.8Ti0.2Co have been systematically studied. Kinetic measurements show that the hydrogenation rate and amount of Zr0.8Ti0.2Co decrease with increasing the ball milling time. However, the dehydrogenation rate accelerates as the ball milling time increases. Meanwhile, the disproportionation of Zr0.8Ti0.2Co speeds up after ball milling and the disproportionation kinetics is clearly inclined to be linear with time at 500°C. It is found from X-ray powder diffraction (XRD) results that the lattice parameter of Zr0.8Ti0.2Co gradually decreases from 3.164 Å to 3.153 Å when the ball milling time extends from 0 h to 8 h, which is mainly responsible for the hydrogen absorption/desorption behaviors. In addition, scanning electron microscope (SEM) images demonstrate that the morphology of Zr0.8Ti0.2Co has obviously changed after ball milling, which is closely related to the hydrogen absorption kinetics. Besides, high-resolution transmission electron microscopy (HRTEM) images show that a large number of disordered microstructures including amorphous regions and defects exist after ball milling, which also play an important role in hydrogen sorption performances. This work will provide some insights into the principles of how to further improve the hydrogen sorption kinetics and disproportionation property of Zr0.8Ti0.2Co. [ABSTRACT FROM AUTHOR]

This study reports the manufacture, microstructure, and tribological behaviour of carbon nanotube reinforced aluminium composites against pure aluminium. The specimens were fabricated using powder metallurgy method. The nanotubes in weight percentages of 0.5, 1.0, 1.5, and 2.0 were homogeneously dispersed and mechanically alloyed using a high energy ball milling. The milled powders were cold compacted and then isothermally sintered in air. The density of all samples was measured using Archimedes method and all had a relative density between 92.22% and 97.74%. Vickers hardness increased with increasing CNT fraction up to 1.5 wt% and then reduced. The microstructures and surfaces were investigated using high resolution scanning electron microscope (SEM). The tribological tests showed that the CNT reinforced composites displayed lower wear rate and friction coefficient compared to the pure aluminium under mild wear conditions. However, for severe wear conditions, the CNT reinforced composites exhibited higher friction coefficient and wear rate compared to the pure aluminium. It was also found that the friction and wear behaviour of CNT reinforced composites is significantly dependent on the applied load and there is a critical load beyond which CNTs could have adverse impact on the wear resistance of aluminium. [ABSTRACT FROM AUTHOR]

The passivation process is of significant importance to produce high-efficiency black silicon solar cell due to its unique microstructure. The black silicon has been produced by plasma immersion ion implantation (PIII) process. And the Silicon nitride films were deposited by inline plasma-enhanced chemical vapor deposition (PECVD) to be used as the passivation layer for black silicon solar cell. The microstructure and physical properties of silicon nitride films were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), spectroscopic ellipsometry, and the microwave photoconductance decay (μ-PCD) method. With optimizing the PECVD parameters, the conversion efficiency of black silicon solar cell can reach as high as 16.25%. [ABSTRACT FROM AUTHOR]

A comparative study between effects of Mn and Al on the properties of ZnO varistor sintered at 1200◦C is investigated byXRD, SEM hardness, and I-V measurements. Although bothMn and Al do not influence the well-known peaks related to wurtzite structure of ZnO ceramics, some other unknown peaks could be formed at higher doping content (≥ 0.10). Also, the shape and size of grains are clearly different for both dopants. Average crystalline diameters, deduced from XRD analysis, are between 42nm and 62 nm, which are 50 times lower than those obtained from SEM micrographs, while the oxygen vacancies deduced from EDAX analysis, are gradually decreased by doping content for both dopants. Interestingly, the values of breakdown field, nonlinear coefficient and barrier height are found to be higher in Mn samples as compared to Al samples, while the opposite is reported for leakage currents, hardness, and electrical conductivities. The values of EB are changed from 2.67 V/cm to 41.67 V/cm for Al, and from 1928 V/cm to 6571 V/cm forMn. The conductivity of Al samples is higher than that of ZnO, and it is nearly (103–105) times the conductivity of Mn samples. These results are discussed in terms of the difference of magnetic moment and valence state between these two additives. [ABSTRACT FROM AUTHOR]