Phase Particles Research Articles

Application of central composite design (CCD)-response surface methodology (RSM) for optimization of heat transfer in dusty nanofluid flow with velocity slip

Background and Purpose The consequence of thermal radiation is scrutinized on the heat transport of Nano-diamond/silicon oil and silver/silicon oil nanofluids through a stretching endless plate. The single phase (Tiwari and Das) model is employed for nanofluid. The major objective of this study is to optimize the RSM-based Central composite design modeling to optimization of the heat transfer in dusty Oldroyd-B nanofluid across stretching surface. Additionally the velocity slip effect is considered. The dust particle phase is also taken into account. The significance of viscous dissipation, joule heating, inclined magnetic field with convective condition is investigated. Methodology The partial differential equations are developed under consideration, then transform to ODE’s by utilizing similarity tools. The transformed model of ODE’s is tackled numerically via bvp4c MATLAB tool with shooting algorithm. The effect of magnetic parameter, fluid interaction parameter, nanoparticle volume fraction, slip parameter and temperature interaction parameter on velocity field and temperature distribution of fluid phase and dust phase is investigated. Furthermore the Nusselt number on the wall is observed for interactive parameters of mass concentration of dust particles, fluid particles interaction parameter for velocity and unsteady parameters utilizing the face-centered Central Composite design (CCD) of the Response Surface Methodology (RSM). Additionally, Analysis of Variance (ANOVA) algorithm and 3D plots are utilized to examine the consequence of experimental design parameters via the response. The recommended model significance has been analyzed in conditions of correlation coefficient ( R 2 ), mean square error (MSE), root means square error (RMSE), prediction standard error to acknowledge the most excellent strong. Results The difference between the Predicted R2 of 0.9467 and the Adjusted R2 of 0.9867 is less than 0.2, which is assumed to be a reasonable concurrence. Furthermore results of the current analysis indicate that velocity gradient for nanofluid is diminishes for larger fluid particle interaction parameter for velocity, while the dust phase velocity is improved. The increment in Temperature gradients is observed via increasing values of the nanoparticle fraction and temperature base fluid particle interaction parameter. From the results it is concluded that skin friction coefficient is reduced with larger magnetic parameter for both mono nanofluids. Furthermore the heat transfer rate is increased by increasing the thermal radiation parameter for both mono nanofluids. It is concluded that silver/silicon oil nanofluid play a higher role in heat transportation as compare to Nano-diamond/silicon oil.

Effect of Cu Addition Above the Solubility Limit on Microstructure Formation and Cu Segregation in 800 MPa Grade Ductile Cast Iron During Solidification

In this study, the effect of 3 mass%Cu additions on microstructure formation and Cu segregation in 800 MPa grade ductile cast iron during solidification was investigated. The calculated phase diagram showed that after the addition of 3 mass%Cu, the Cu phase with a negligible amount appeared below 1000°C, and most Cu was included in the matrix. Based on optical microstructure, after the addition of 3 mass%Cu, the size of graphite nodules became finer, and the microstructure rarely had an area with α-ferrite. Image analysis showed that the fraction of pearlite increased significantly, indicating that Cu greatly promoted the formation of pearlite. Compositional analysis by scanning electron microscopy indicated that the pearlitic area also contained approximately 3 mass%Cu, which corresponds to those of primary and secondary austenite calculated. A small and bright phase particle containing a large amount of Cu was observed at the interface of graphite and matrix.

Properties of Ni-B/B Composite Coatings Produced by the Electroless Method under Semi-Technical Line Conditions

Composite coatings have been successfully fabricated at the laboratory scale in many research centers around the world; however, it is still a major challenge to transfer the positive results of the work to the industrial scale. This paper presents the technology for the production of Ni-B and Ni-B/B composite coatings on a pilot experimental semi-technical line by chemical reduction. A process scheme for the fabrication of Ni-B layers and composite coatings with a nickel–boron matrix and a dispersive phase in the form of boron nanoparticles was developed. All stages of the fabrication process were described in detail. The dispersion phase of the boron particles was characterized, and the performance properties of the Ni-B and Ni-B/B composite coatings produced on a pilot electroplating line were studied. The structure and morphology of the Ni-B/B composite coatings were characterized for comparison with nickel–boron coatings. Their mechanical and tribological properties and adhesion to the substrate were studied. The influence of the dispersion phase of boron particles on the structure and functional properties of the composite coatings was evaluated. In order to improve the performance of the fabricated coatings, a heating process at 400 °C was carried out, and the performance of Ni-B and composite Ni-B/B coatings was studied after the heat treatment operation.

Solution combustion synthesis of iron-based magnetic nanoparticles: influence of inert gas pressure

We report the synthesis of iron oxide nanoparticles using solution combustion synthesis, focusing on the controlled manipulation of material characteristics, such as particle size, phase composition, and magnetic properties, by applying external inert gas pressure. It was shown that variation of nitrogen gas pressure in the reactor in the range 0.1 to 1.1 MPa changed the time-temperature history of the process and resulted in the gradual change of phase composition of the fabricated materials along the FeO → FeO∙Fe2O3 → Fe2O3 route. The particle size varied in the 50–400 nm range, with a maximum for powder synthesized at a pressure of 0.25 MPa. For magnetic fluid hyperthermia, the critical parameter is specific loss power. It was demonstrated that this parameter can be optimized by gas pressure variation. The maximum specific loss power measured under conditions suitable for magnetic hyperthermia (magnetic field 33.5 mT and frequency 259.6 kHz) appears to be 174 W/g. The proposed innovative approach is an effective tool for controlling the synthesis of various nanoparticles with desired properties.

Effect of laser energy density on cracking susceptibility and wear resistance of laser-clad tribaloy T-800 coatings on DD5 single-crystal alloys

In order to enhance the wear resistance of DD5 single-crystal alloys, Tribaloy T-800 wear-resistant coatings were prepared on their surfaces using laser-cladding technology. This study examines the effect of laser energy density on the cracking susceptibility and wear resistance of laser-clad Tribaloy T-800 coatings on DD5 single-crystal alloys. Three distinct laser energy densities (η1=33 J/mm², η2=50 J/mm², η3=60 J/mm²) were applied to create the coatings. The results show that the microstructures of the T-800 laser-clad coatings mainly consist of primary, coarsened, and spheroidized Laves phases, as well as Co-based solid solution and eutectic structures. The phases include Co3Mo2Si phase (Laves phase) and face-centered cubic Co-based solid solution. However, increasing laser energy density enhanced elemental diffusion at the heterogeneous joining interface of the DD5 substrate/T-800 coating, leading to higher Ni content in the coating. This resulted in a reduction in the tendency and content of Mo-rich Laves phase formation respective contents of 53.2 %, 49.2 %, and 47.5 %. Moreover, the decrease in the difference between laser cladding temperature and initial temperature, ∆T, led to reduced thermal stress at the interface, σ, contributing to a decrease in cracking susceptibility (a), with corresponding values of 0.16184, 0.00034, and 0.00022. Thermal expansion coefficients of materials in the cracked region near the interface, measured according to the CALPHAD method, Jmatpro software, and average EDS elemental content data at the crack edge, surpassed those of the corresponding DD5 substrate. Consequently, cracks in the coatings originated from stretching at the interface, with paths tending to cross Laves phase particles in a cleavage mode. The average microhardness of the coatings decreased due to reduced Laves phase content, with values of 783.4 HV0.5, 741.7 HV0.5, and 708.2 HV0.5, respectively, while the fatigue wear of T-800 coatings increased due to exacerbated wear damage from cracking defects. Specifically, average COFs were 0.659, 0.583, and 0.506, with corresponding mass losses of 7.1 mg, 3.4 mg, and 2.9 mg, respectively. The wear mechanisms observed encompassed fatigue wear, abrasive wear, and oxidative wear.

Occurrence, transport and sources of metals and metalloids in the Bangpakong River in the eastern economic corridor area of Thailand

The occurrence of elements in river water is affected by various factors, including mobility, weathering and transport processes and anthropogenic contributions. A total of six water sampling campaigns were conducted from 2021 to 2022 to study the factors affecting the occurrence of twelve elements (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn and Se) in the Bangpakong River. The total concentrations of all the elements were within the levels set by the national surface water quality standard. Comparisons of dissolved elemental concentrations in the study area with the global average for dissolved elemental concentrations in pristine rivers indicated contamination with Al, As, Co, Mn, Zn and Se in the river water. Based on the percentage of each element in particulates to the total concentration, Al (80.6 %), Cr (71.9 %), Cu (69.9 %), Fe (95.6 %), Mn (76.6 %), Pb (74.7 %), and Zn (70.6 %) were mainly transported in the particulate phase in both the dry and wet seasons. However, As (65.5 %), Co (60.3 %), and Se (77.6 %) were mainly transported in the dissolved phase in both seasons. The ratios of the dissolved Se concentration in river water to the Se concentration in the Earth's crust indicated significant and high mobility, especially in downstream sites, likely due to Se leaching from alluvial sediments. Seawater intrusion is likely the cause of As and Zn contamination in the dry season. Weathering of rocks and soils likely causes Al, Co, and Mn contamination in the wet season. The anthropogenic sources of contamination include the discharge of Mn and Zn from fertilizers in agriculture and the use of formulated feed in aquaculture. Approximately 52.98, 25.23, 5.68 and 0.63 tons of Fe, Al, Mn and Zn, respectively, are estimated to be transported from the river into the Gulf of Thailand each year.

Assessment of organic contaminants at a paint manufacturing site: Implications for health risks and source identification

The daily variation of organic contaminants, both gaseous and associated with suspended particulate matter (PM), was investigated within the estate of the National Company of Paintings in Lakhdaria, Algeria, spanning the period 2014-2015. The research emphasizes the chemical characterization of suspended PM, analyzing a range of organic compounds, including n-alkanes, polycyclic aromatic hydrocarbons (PAHs), and highly polar organics (HPOC), such as phthalate esters and heterocyclic compounds. Vapors of PAHs and polychlorobiphenyls (PCBs) were also analyzed. Low molecular weight compounds were primarily associated with the gas phase (two-ring PAHs, approximately 95%; three-ring PAHs, around 70%), while high molecular weight congeners were mainly associated with the particle phase (six-ring PAHs, 55%). The concentrations of PCBs (ranging from 0.6 to 42 ng m–3) were higher than those reported in other cities in Algeria and Europe. The source reconciliation of organic contaminants through principal component analysis (PCA) demonstrated that the primary sources were petroleum combustion, industrial manufacturing, tobacco smoking, and vehicular traffic. The significance of tobacco smoke was further confirmed by the analysis of PAH diagnostic ratios. Differences in the rates of diagnostic ratios between gaseous and particulate PAHs were attributed to distinct contributions from sources such as industrial processes. Health risks for workers exposed to PAHs and PCBs in PM < 10 μm (PM10) were quantitatively assessed in terms of benzo[a]pyrene equivalent concentration and incremental lifetime cancer risk (ILCR). The ILCR presents novel findings showcasing heightened risks among workers exposed to specific PAHs within production areas, whereas those related to PCBs suggested a high potential of health risks for laboratory workers.

Study on hardenability of 2050 Al–Cu–Li alloy ultra-thick plate

The hardenability of the 2050 Al–Li alloy ultra-thick plate was evaluated by end quenching and interrupted quench methods. Microstructural investigation at different thickness positions after quenching and aging were conducted using optical microscopy, scanning electron microscope, and transmission electron microscope. The factors affecting the hardenability were discussed in combination with cooling rate and composition examination using energy dispersive spectroscopy. The results indicated that the tensile strength of different thickness positions decreased as the distance from the quenching end increases. Coarse Cu-rich phase particles, formed at the grain and grain boundaries during the end quenching process, lead to solute depletion around the grain boundaries, causing a precipitate-free zone. This zone obstructs the formation of the T1 phase, thereby reducing strength. At identical distances from the quenching end, the tensile strength at the mid-thickness (T/2) location consistently exceeds that at the quarter-thickness (T/4) location. This is due to the original microstructural differences, where the T/2 position experiences a slower cooling rate, has a lower copper content, and shows an increase in the number but a decrease in the size of precipitated coarse Cu-rich phase particles from the supersaturated solution, with the solute consumption remaining relatively constant. Consequently, the tensile strength variation at equal distances from the quenching end is minimal.

Comprehensive methodology for semi-volatile organic compound determination in ambient air with emphasis on polycyclic aromatic hydrocarbons analysis by GC–MS/MS

Polycyclic aromatic hydrocarbons are air pollutants that affect the human health and the environment, and their accurate determination in outdoor and indoor environments is important. This study presents a methodology for sampling and analysis of semi-volatile compounds in ambient air with emphasis on the polycyclic aromatic hydrocarbons, collected with low-volume pumps (4.8 m3) in unconditioned solid phase extraction cartridges (Isolute ENV+). Sampling in SPE cartridges with low-volume pumps allows the collection of both gas and particulate phase compounds in indoor as well as outdoor environments, and reduces the number of extraction steps required as well as the solvent volume used for extraction. Analysis of the 16 US-EPA priority PAHs after extraction was conducted by GC–MS/MS with recoveries of the PAHs 40–118 %. No breakthrough was detected during sampling. Moreover, the methodology includes storage test to assess the conservation of PAHs in the SPE cartridges in heat-sealable Kapac bags; simulating transport from sampling sites to laboratory, and storage under room, cold and frozen conditions at different time-intervals, up to 3 months after sampling. The results showed that concentration levels remained constant across various storage time intervals and temperatures, with naphthalene and acenaphthylene being the only exceptions, showing high blank levels for the first and losses at room temperature for the later. The method quantification limits, including sampling, storage and GC–MS/MS analysis ranged from 2000 pg m-3 for naphthalene and 300 pg m-3 for phenanthrene to less than 20.0 pg m-3 for higher molecular and less volatile PAHs, such as benzo[a]pyrene (LOQ = 8.0 pg m-3). The feasibility of the method was tested by sampling indoors under urban background air conditions, showing individual PAH concentrations 4 to 10 times higher than their method quantification limits.

Emission of Intermediate Volatile Organic Compounds from Animal Dung and Coal Combustion and Its Contribution to Secondary Organic Aerosol Formation in Qinghai-Tibet Plateau, China.

Intermediate volatility organic compounds (IVOCs) are important precursors to secondary organic aerosols (SOAs), but they are often neglected in studies concerning SOA formation. This study addresses the significant issue of IVOCs emissions in the Qinghai-Tibetan plateau (QTP), where solid fuels are extensively used under incomplete combustion conditions for residential heating and cooking. Our field measurement data revealed an emission factor of the total IVOCs (EFIVOCs) ranging from 1.56 ± 0.03 to 9.97 ± 3.22 g/kg from various combustion scenarios in QTP. The markedly higher EFIVOCs in QTP than in plain regions can be attributed to oxygen-deficient conditions. IVOCs were dominated by gaseous phase emissions, and the primary contributors of gaseous and particulate phase IVOCs are the unresolved complex mixture and alkanes, respectively. Total IVOCs emissions during the heating and nonheating seasons in QTP were estimated to be 31.7 ± 13.8 and 6.87 ± 0.45 Gg, respectively. The estimated SOA production resulting from combined emissions of IVOCs and VOCs is nearly five times higher than that derived from VOCs alone. Results from this study emphasized the pivotal role of IVOCs emissions in air pollution and provided a foundation for compiling emission inventories related to solid fuel combustion and developing pollution prevention strategies.

Effect of Gadolinium Content on the Microstructures and Corrosion Properties of Mg-4Zn-3Gd Alloy

Lightweight metallic alloys in the transport sector are the essential choice to reduce carbon monoxide emissions. Magnesium (Mg) can serve this purpose appreciably because it has a low density compared to other metallic metals and a high strength in a small portion of metals. The reason behind this is having very low weight. Notwithstanding the alloys exhibit high susceptibility to corrosion especially galvanic corrosion, which impedes it from its various applications. The corrosion resistance of magnesium alloy depends largely on the surface film whether it can protect well and the corrosion due to galvanic effect between the second phase particles or microstructures and the magnesium matrix. Role of second phase particles eventually improves the corrosion property by enhancing its resistance to corrosion. Mg-4Zn being a promising alloy, 3 wt% Gd has been added further to investigate the corrosion resistant properties of Mg-4Zn-3Gd alloy. After preparing the alloys by casting method in induction furnace followed by homogenization at 410°C, the sample was hot rolled at 400°C. Preparation of the samples has been verified by EDS, XRF and XRD analysis. Corrosion study has been done for 1 hour, 24 hours and 72 hours. Microstructures have been taken for as cast, homogenized, and as rolled condition before corrosion test. The analysis shows a large difference in the grain size and phase distribution. Due to dynamic recrystallization during rolling hardness also shows differences compared to as cast and homogenized sample. The corrosion test is performed by weight loss test, electrochemical measurement, and immersion test. In the results, it has been seen an increase in corrosion rate at the initial stage, however it came to a constant rate after some time. After corrosion test, optical micrographs (OM) and scanning electron microstructures (SEM) images show typical morphology of corroded surface with some micro cracks. The presence of Gd in Mg-4Zn alloy enhanced the corrosion performance when it is done for longer time.

Multimedia distribution and release characteristics of emerging PFAS in wastewater treatment plants in Tianjin, China

Legacy and emerging PFAS in the air, wastewater, and sludge from two wastewater treatment plants (WWTPs) in Tianjin were investigated in this study. The semi-quantified nontarget PFAS accounted for up to 99 % of ƩPFAS in the gas phase, and aqueous film-forming foam (AFFF)-related PFAS were predominant in wastewater (up to 2250 ng/L, 79 % of ƩPFAS) and sludge (up to 4690 ng/g, 95 % of ƩPFAS). Furthermore, field-derived air particle-gas, air-wastewater, and wastewater particle-wastewater distribution coefficients of emerging PFAS are characterized, which have rarely been reported. The emerging substitute p-perfluorous nonenoxybenzenesulfonate (OBS) and AFFF-related cationic and zwitterionic PFAS show a stronger tendency to partition into particle phase in air and wastewater than perfluorooctane sulfonic acid (PFOS). The estimated total PFAS emissions from the effluent and sludge of WWTP A were 202 kg/y and 351 kg/y, respectively. While the target PFAS only accounted for 20–33 % of the total emissions, suggesting a significant underestimation of environmental releases of the nontarget PFAS and unknown perfluoroalkyl acid precursors through the wastewater and sludge disposal. Overall, this study highlights the importance of comprehensive monitoring and understanding the behavior of legacy and emerging PFAS in wastewater systems, and fills a critical gap in our understanding of PFAS exposure.

Counter-intuitive mechanical performance variation in aged low-temperature interconnections in electronic packaging

Different from the conventional aging induced continuous mechanical performance deterioration in solder joints, a counter-intuitive “decrease-increase-decrease” variation in shear strength with a peak value 12 MPa higher than the initial state was captured in aged low-temperature BGA structure Cu/Sn–58Bi/Cu solder joints. The first decrease in shear strength was dominated by the coarsening of Sn and Bi phases. The following increase in shear strength was rooted in the concurrent Bi subgrain strengthening, solid solution strengthening of Bi element in Sn-rich phase and precipitation strengthening induced by the Bi-rich phase particles. The eventual decrease in shear strength was ascribed to severely deteriorated interface between the solder matrix and intermetallic compound layer being the weaker site in the long time aged solder joint. This aging induced strengthening phenomenon is inspiring in mechanical performance optimization and reliability elevation of SnBi-based solder joints for the coming chiplet and heterogeneous integration packaging.

A STUDY OF PROPERTIES OF AUSTENITIC STEEL IN THE INITIAL STATE

High-manganese steel is used in the rocket, space, and defense industries due to its low specific gravity, stable austenitic structure over a wide temperature range, and ability to strengthen under mechanical deformation. However, the wider application of this steel is hindered by such factors as: instability of mechanical properties in the initial state, tendency to thermal embrittlement and very poor machinability. Therefore, the work is aimed at solving the problems of eliminating the above-mentioned negative factors. Conducted studies of the effect of temperature-time parameters on the structure and properties of steel made it possible to establish the mechanism of thermal embrittlement of 9Г28Ю9МВБ steel. During slow cooling from hot deformation temperatures with speeds of the order of 0.03 º/s in steel, a large number of gray-blue coarse phase particles are released, which are located on the grain boundaries, which causes a sharp decrease in impact viscosity. It was established that in the temperature range of 500-800 ºС, the solid solution disintegrates with the release of particles of the strengthening K-phase - (Fe, Mn)3 AL, Cx. It was determined that the simultaneous decrease in hardness and impact strength in the temperature range of 750-950ºС provides a significant improvement in machinability. The lowest values of mechanical properties are achieved during aging at 700 ºС, the improvement of machinability in this case is maximal compared to exposure to other temperatures. So, for example, with an increase in the temperature of isothermal holding at 650ºС for 35 hours. machinability improves by almost 1.7 times, and for the same time at 700 ºС – by 2.4 times. When the holding temperature is increased to 950ºС for 35 hours. the machinability of steel increases only 1.6 times, which is due to the less intense decomposition of the saturated solid solution. Significant anisotropy of mechanical properties is formed as a result of the development of liquid chemical heterogeneity and its imitation during further thermomechanical processing. The value of the coefficient of anisotropy in sample bars of different grades of initial steel reaches values from 1.5 for a bar with a cross section of 105x105 mm to 3.9 units for a bar with a diameter of 120 mm. The study of the influence of the annealing temperature on the homogeneity of austenitic steel made it possible to develop a mode of heat treatment of austenitic steel 9Г28Ю9МВБ, which consists of heating to 1250°С, holding for 2 hours. at this temperature and subsequent cooling in water, in order to fix a homogeneous supersaturated solid solution. After such heat treatment, the striated microchemical heterogeneity is significantly reduced, the anisotropy coefficient does not exceed 1.1 units for all types of steel assortment.

Structure and magnetic properties of SmCo4.5Cu0.3Sn0.16Ga0.04 ribbons melt-spun at 10–40 m/s

The anisotropic Nd-Fe-B magnets prepared by as-spun ribbons using hot-pressing and hot-deformation methods have been commercialized. However, the Sm-Co magnets face challenges in obtaining strong c-axis deformation textures due to the absence of a low-melting intergranular phase to facilitate grain deformation. After simultaneously adding gradient low-melting metals of Cu, Sn, and Ga to SmCo5 alloy, SmCo4.5Cu0.3Sn0.16Ga0.04 ribbons were prepared by melt-spinning at 10–40 m/s. These ribbons comprise the Sm(Co, M)5 main phase, Sn-rich Sm2(Co, M)7 grain boundary phase, and Sm117Co55.58Sn115.94-type particulate phase. Notably, the ribbons melt-spun at 30 m/s contain the highest Cu, Sn, and Ga content in the grain boundary phase, making them most suitable for producing hot-pressed and hot-deformed magnets. Additionally, the ribbons melt-spun at 20 m/s have a maximum coercivity of 26.4 kOe, while those melt-spun at 40 m/s have the highest magnetization of 61.6 emu/g.

Effect of total content of Zn and Mg on microstructure and mechanical properties of Al-3.2xZn-xMg-1.66Cu-0.15Zr aluminum alloy sheet

The effects of total Zn and Mg content on the microstructure, tensile properties, and fatigue properties of Al-3.2xZn-xMg-1.66Cu alloy sheets were systematically investigated after aging at 120 °C for 24 h. As the total content of Zn and Mg increased, the recrystallized grains were gradually refined, and the types of precipitate particles did not change, all of which comprised Guinier Preston (GP) zones and η′ metastable-phase particles, whereas both the number and volume fraction of η′-phase particles increased gradually, where the particles were first coarsened and then refined. The η′-phase particles were largest (∼8.2 nm) in the alloy with the total Zn and Mg content of 5.15 wt.%. The grain boundary precipitate (GBP) gradually coarsened and the width of the precipitates free zone (PFZ) gradually decreased. When the total content of Zn and Mg was increased from 2.61 to 11.40 wt.%, the yield strength and tensile strength increased from 173 and 309 MPa to 554 and 620 MPa, respectively, whereas the elongation decreased from 29.9% to 8.5%. However, the fatigue strength of the alloy sheet first decreased from 149 to 119 MPa and then increased to 183 MPa under the condition of R = 0.1. The fatigue strength of the alloy sheet with total Zn and Mg contents of 5.15 and 11.40 wt.% were the lowest one and the highest one, respectively, and the latter was 54% higher than the former.

A CFD numerical simulation of particle deposition characteristics in automobile tailpipe: power abatement pathways

The study of the movement of pollutants through ducts facilitates the assessment and control of ambient air quality problems (AQ). Among other things, understanding the deposition and distribution of particulate matter in elbows is important for practical engineering applications. In this study, the turbulent flow field and particle deposition in a 90° bend is investigated using RANS simulation. The RNG k-ε turbulence model was employed to calculate the airflow flow field and the discrete phase model (DPM) was used to simulate the particle phase motion. Where for the discrete phase, the Discrete Random Wander (DRW) model was considered and the deposition of particles with sizes of 1, 3, 5, 10, 20, and 40 μm in the flow field was investigated separately. Grid-independent validation of the models used in the simulations was performed. The effects of inlet velocity, particle size, and direction of gravity on the flow field and particle deposition in the elbow were considered. The results show that the flow field in the bend is strongly influenced by the above parameters. Among them, the turbulent disturbance in the bend section is the most intense, with high turbulent energy value, and it is also the region with the largest energy loss. The inlet velocity is negatively correlated with the deposition rate, and the particle size is positively correlated with the deposition rate.

Evaluation of the effect of strontium and tungsten carbide on the microstructure evolution, tribological and mechanical behaviour of Al-Zn-Mg-Cu-5Sr-WC metal matrix composite

The present study focused on the experimental investigation of the metallurgical, tribological, and mechanical behavior of the developed Al-Zn-Mg-Cu-Sr-WC (Al7075-Sr-WC) metal matrix composite. The effect of the reinforcements such as strontium and tungsten carbide (WC) along with a 2 wt% magnesium as the wetting agent during the stir casting of the synthesized aluminum metal matrix composite (MMC) was investigated by varying the weight percentages. The microstructure examination was characterized using field emission scanning electron microscopy (FE-SEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive spectroscopy (EDS) techniques. Wear analysis and mechanical testing were conducted to study the effect of WC particles in the matrix phase by examining their wear rate, tensile strength, proof strength, and hardness values. From the mechanical and tribological tests, it was observed that there was an increase of 55% in hardness and 43% in tensile strength, along with a 31% reduction in wear rate. The secondary phases revealed from XRD analysis lead to more hardness along the refined grain boundaries. The tensile strength of the composite initially increased with a 3 wt% of WC and 5 wt% strontium due to hindrance to the dislocation movement but decreased with more reinforcement particles caused by brittleness. The hard WC particles presence has reduced the wear rate significantly due to its resistance towards abrasive wear and lubricating effect. The unique combination of a grain refiner and a binder helped develop a novel composite with superior characteristics that could replace many aerospace components made up of Al7075 alloy.

Sonochemical synthesis of silver nanoparticles using orange juice: Cytotoxic behaviour and applications

One-pot open beaker green synthesis of silver nano-particles (Ag NPs) by ultrasound energy at room temperature is presented. Citrus fruit-mediated Ag NPs formation was monitored by observing surface plasmon resonance (SPR) by UV–Visible measurements. Orange juice extract played a dual role as it helped in the surface capping of Ag NPs while being a reducing agent to yield phase pure silver nanoparticles of less than 10 nm diameter. The phase purity and particle diameter were confirmed by X-ray diffraction (XRD) patterns and organic functionality was established by infra-red spectroscopy. The morphology was understood by AFM and SEM. Additionally, the study investigates the antioxidant activity and antimicrobial efficacy of so-synthesized Ag NPs against pathogenic microorganisms such as E. coli. and S. aureus. The study also assesses the anticancer activity of Ag NPs on four different cancer cell lines (A 2780, MDA-MB-231, A 375, and HepG2). The half maximal inhibitory concentration (IC50) of nano-silver sample SS-1 was about 5 μg against A 2780 and MDA-MB-231 cell lines.

Effects of lanthanum and ethylenediamine tetraacetic a cid

Using nickel-tungsten as active metals and TiO₂-Al₂O₃ as the support, Ni-W/TiO₂-Al₂O₃ catalysts for the hydrodesulfurization of heavy oil were prepared by wetness impregnation. The effects of the modification of lanthanum, ethylenediamine tetraacetic acid (EDTA)and La in cooperation with EDTA on the structure and hydrodesulfurization performance of the catalysts were investigated. The catalysts were characterized by XRD, BET, H₂-TPR and SEM. The results indicated that La and EDTA could weaken the interaction between support and active component, facilitate the reduction of active component, and benefit the formation of Ni-W-S phase. Addition of La or EDTA could increase the surface area and suppress the agglomeration of active metals on surface, forming smaller and highly dispersed active phase particles. The La, EDTA and combined La and EDTA modified catalysts possessed higher HDS activity than Ni-W sample, Ni-W-La-E catalyst had the highest HDS activity, and its thiophene conversion reached 99.7%.