Size Of Agglomeration Research Articles

Unlocking the Strength of Nanocomposites: Mitigating the Impact of Nanoparticle Agglomeration on Tensile Performance

This study investigates the substantial impact of nanoparticle aggregation on the tensile strength of nanocomposite materials. Nanoparticles measuring between 10 nm and 30 nm were examined using deliberate controlled agglomeration. The smallest agglomeration size was 10 nm, while the largest was 30 nm, indicating a 200% increase in agglomerate size based on the characterization data. The equally dispersed nanoparticles in the control group also measure an average tensile strength of 53MPa from the tests conducted. On the other hand, observed that the tensile strengths of nanocomposites with introduced agglomerates were lower. In the current study, a 34% reduction was observed for samples with agglomerates of 30 nm to a value of 35 MPa from the control. On the other hand, the sample prepared with the agglomerates of size 10 nm and 15 nm provided 50 MPa and 45 MPa of strength, respectively. Outcome shows that tensile strength is in negative correlation with the size of agglomeration and therefore, yield that the larger agglomerate reduce the mechanical properties of the nanocomposites. This study stresses that the agglomeration has to be regulated, and how the formation of nanoparticle clusters have a negative impact on the tensile strength of the nanocomposites, in order to enhance the mechanical properties of nanocomposite materials. These findings are useful in planning improved nanocomposites with improved mechanical properties for use in a wide-range of applications in engineering.

Combustion Instability and Ash Agglomeration in Wood Pellets Boiler

The combustion instability and ash agglomeration in a wood pellet boiler were investigated in this study. The tests were conducted using the Taguchi method of orthogonal array L27(133). Several parameters are applied, including grate area (GA), primary to secondary air split ratio (SR), excess air (EA), and fuel power (P). Pine wood pellets were used, and the boiler’s nominal load was 20 kW. The results show that instability during combustion occurs since the fuel bed rises as the accumulation of the unburned wood pellets on the grate causes a slow combustion rate and pressure drop, which creates noise and disturbances. A good combination of the parameters applied to TN9 and TN20 can be useful in obtaining stable combustion. In addition, the ash agglomerations were influenced by the duration of the combustion and the temperature of the fuel bed. The largest size of the ash agglomeration was referred to as test number-TN26 (P: 16 kW, EA: 110%, SR: 30/70, and GA: 115 mm × 75 mm), which is 59 mm, and the duration time is 14,400 s (≈4 h).

Micro-sized nanoaggregates: Spray-drying-assisted fabrication and applications

The applications of nanoparticles suffer from their extremely small size and intrinsic trend of agglomeration. Rearranging nanoparticles to form micro-sized nanoaggregates (MNAs) with increased size, ordered structure, as well as controllable size, shape, and morphology is a crucial step in various fields of science and technology to maintain the unique characteristics of nanoparticles while obtaining greatly enhanced or new performance at the microscale. The structure of MNAs prominently affects their functionality, which is determined by the arrangement of nanoparticles and the interaction between primary particles. Several methods have been proposed to prepare the MNAs, in which spray-drying technology stands out considering the feasibility, scalability for industry, cost, and efficiency. Forced assembly of nanoparticles through spray-drying under tunable process parameters yields diverse physical properties and structural arrangements of nanoparticles of the MNAs, they therefore exhibit enormous potential in a wide range of application fields. This review presents the construction and applications of spray-dried MNAs. The factors that influence the size, morphology, and structure of the MNAs are discussed in detail. In addition, the outstanding application performance resulting from the tightly packed nanoparticles in regular-shaped MNAs obtained by the spray-drying process is illustrated.

Building the Bridge From Aquatic Nanotoxicology to Safety by Design Silver Nanoparticles.

Nanotechnologies have rapidly grown, and they are considered the new industrial revolution. However, the augmented production and wide applications of engineered nanomaterials (ENMs) and nanoparticles (NPs) inevitably lead to environmental exposure with consequences on human and environmental health. Engineered nanomaterial and nanoparticle (ENM/P) effects on humans and the environment are complex and largely depend on the interplay between their peculiar properties such as size, shape, coating, surface charge, and degree of agglomeration or aggregation and those of the receiving media/body. These rebounds on ENM/P safety and newly developed concepts such as the safety by design are gaining importance in the field of sustainable nanotechnologies. This article aims to review the critical characteristics of the ENM/Ps that need to be addressed in the safe by design process to develop ENM/Ps with the ablility to reduce/minimize any potential toxicological risks for living beings associated with their exposure. Specifically, we focused on silver nanoparticles (AgNPs) due to an increasing number of nanoproducts containing AgNPs, as well as an increasing knowledge about these nanomaterials (NMs) and their effects. We review the ecotoxicological effects documented on freshwater and marine species that demonstrate the importance of the relationship between the ENM/P design and their biological outcomes in terms of environmental safety.

Boosting diesel soot catalytic combustion via enhancement of solid(catalyst)-solid(soot) contact by tailoring micrometer scaled sheet-type agglomerations of CeO2-ZrO2 catalyst

Solid(catalyst)-solid(soot) contact is a crucial factor in diesel soot catalytic combustion, and rationally optimizing solid(catalyst)-solid(soot) contact is a promising yet challenging pathway for improving catalytic diesel soot combustion performance. Here, we report a micrometer scaled sheet-type CeO2-ZrO2 soot oxidation catalyst. The nitrogen adsorption-desorption result indicates that soot particulates are barely able to enter into the inner pore of the catalyst (average pore size < 20 nm) due to the large size of filamentous soot agglomeration (reaching up to 1 μm). Thus the catalyst-soot contact mainly depends on the catalyst external surface and morphology. Electron microscope images confirm the presence of microsheet agglomerations of the prepared CeO2-ZrO2 catalyst, which is an advantage for enhancing the adherence of soot filaments on catalyst. Compared to common CeO2-ZrO2 particle catalyst, the CeO2-ZrO2 microsheet shows a remarkably higher macrolevel soot combustion performance. Interestingly, the single catalytic site activity (intrinsic activity) of CeO2-ZrO2 microsheet is not enhanced by the micro-structure. Thus the enhanced soot combustion efficiency could be ascribed to the improving of catalyst-soot contact. And therefore, this work suggests that constructing structured catalyst at micrometer level is an efficient way to improve the solid(catalyst)-solid(soot) contact efficiency and thereby boost the diesel soot combustion performance.

Analysis of agglomeration particle size near the burning surface of aluminized solid propellant based on digital inline holography

Aluminum powder can increase the specific impulse and improve the combustion performance of a solid propellant; however, agglomeration can result in the loss of two-phase flow, a decrease in specific impulse of the propellant, and an increase in the thermal protection pressure of the motor structure. This study employs digital inline holography, which offers the advantage of non-contact three-dimensional measurements, to investigate the agglomeration particle size near the burning surface. This study aims to quantitatively analyze these particle size data to determine the effects of pressure, ammonium perchlorate particle size, coarse and fine ammonium perchlorate content ratio, and aluminum particle size on the agglomeration particle size distribution. The experimental results indicate that increasing the pressure from 0.1 MPa to 0.8 MPa reduces the average particle diameter of agglomeration by at least 9.6%, results in a more concentrated agglomeration particle size distribution, and decreases the volume and number proportion of agglomeration by approximately 7% and 17%, respectively. Furthermore, when the particle size of ammonium perchlorate decreases from 250 μm to 90 μm, the agglomeration particle size distribution becomes more concentrated, the average diameter of agglomeration decreases by at least 37.4%, and the number and volume proportion of agglomeration decrease by approximately 13% and 44%, respectively. The ratio of coarse and fine ammonium perchlorate content has a nonlinear effect on agglomeration. When this ratio is 0.6, the average agglomerate diameter decreases by at least 16%, the agglomeration particle size distribution is more concentrated than that the ratio is 0.39 and 1.29, and the agglomeration number and volume fraction decrease by more than 6% and 32%, respectively. Moreover, decreasing the initial aluminum particle size from 30 μm to 15 μm reduces the average agglomeration particle diameter by more than 21.6%, results in a more concentrated agglomeration particle size distribution, however, increases the number and volume proportion of agglomeration by approximately 17% and 8%, respectively. The conclusions of this study are expected to be significantly helpful in optimizing propellant formulation, reducing the particle size of aluminum agglomeration, and improving the combustion performance of propellants.

Biofunctionalization of Porous Ti Substrates Coated with Ag Nanoparticles for Potential Antibacterial Behavior

Ti prosthesis have shown better biological compatibility, mechanical performance, and resistance to corrosion in cases of bone replacements. Nevertheless, fully dense Ti in connection with bone-host tissues show stress-shielding phenomenon that, together with the development of frequent undesirable microbial infections, may lead to implant failures. To overcome these issues, the present study aimed at the development of a novel combination of a chemically functionalized porous Ti substrate with a potentially therapeutic AgNPs coating. Fully dense and porous Ti substrates (30 and 60 vol.%, 100–200 and 355–500 μm, as spacer particles) were studied. Ti surface was treated with acid or basic medium followed by silanization and deposition of AgNPs by “submerged” and “in situ” methods. In general, for similar porosity, mechanical resistance decreased as pore size increased. Acidic reagent and submerged methodology were the best combination for fully dense Ti substrates. Hence, they were also employed for porous Ti substrates. Depending on the porosity of the substrates, variations can be observed both in the size and degree of agglomeration of the deposited AgNPs, entailing differences in the antibacterial behavior of the samples.

Effects of Ti addition on the microstructure and mechanical properties of Al–Zn–Mg–Cu–Zr alloy

The effects of Ti addition (0.1 wt%) on the microstructure evolution and mechanical properties of an Al–7.6Zn–2.6Mg–2.0Cu–0.1Zr alloy were investigated during solidification, extrusion, solution treatment, and aging. The addition of Ti reduces the grain size and degree of phase agglomeration during solidification, thereby improving the strength and ductility of the as-cast alloy. The extrusion forms a bimodal structure consisting of fine dynamically recrystallized (DRXed) grains and coarse elongated unDRXed grains. Ti induces the refinement of the η-phases that enhances dynamic recrystallization (DRX) by particle-stimulated nucleation, resulting in reduced strength of the as-extruded alloy. The dissolution of the η-phase occurs in the initial stages of the solution treatment, followed by coarsening of the η-phase. The solution treatment causes static recrystallization and grain growth, increasing the grain size. The addition of Ti decreases the size and increases the number density of the L12 precipitate by modifying the chemical composition of (Al,Zn)3Zr into (Al,Zn)3(Zr,Ti), and causes the formation of an Al18Mg3Ti2 phase during the solution treatment. The addition of Ti also enhances heterogeneous nucleation of η-Mg(Zn,Cu,Al)2 at the Al18Mg3Ti2 interface and grain boundary but has a negligible effect on the formation of nanoprecipitates (GPII zone, η') in the matrix. The improved strength and ductility of the solution-treated and aged alloys are attributed to the higher number density of the fine L12-(Al,Zn)3(Zr,Ti) precipitates and grain refinement, as well as the finer η-phases acting as cracking sites.

Morphology and Mechanical Properties of LDPE, EVA and Fly Ash Composites

The fly ash from Pha Lai power plant was modified by vinyltrimetoxysilan (VTMS). The polymer composites based on low-density polyethylene (LDPE), ethylene vinyl acetate copolymer (EVA) and fly ash (FA) without and with vinyltrimetoxysilan (VTMS) modification were prepared by melt mixing in a Haake Rheomixer. The tensile strength and elongation at break of the LDPE/EVA/VFA composites were also higher than those of the LDPE/EVA/FA composites. The FESEM images proved that FA-VTMS particles disperse more regularly in the polymer matrix in comparison with FA without VTMS modification. In addition, the surface modification of the FA reduced the size of agglomeration of FA particles.

Transformation of social and liturgical practices of Perm religious organizations under the influence of lockdown and the pandemic

The article provides a brief description of the religious space of the Perm region and analyzes social and liturgical practices and possible options for their transformation as a result of self-isolation of residents of the Perm region from April to December 2020. There is a General trend towards the virtualization of religious space, the use of which ceases to be specific only for new religious teachings. Traditional religious denominations are beginning to actively use the Internet space, offering believers a virtual religious product, however, an important assumption is made that traditional organizations are not ready to completely replace traditional social and liturgical practices, which are an important part of the religious process, with their virtual counterparts. The article clarifies the concept of «religious practices» and suggests that the speed of transformation processes depends on the size of urban agglomeration and the complexity of building a religious space in a particular area. In particular, the analysis of Protestant religious space, high organizational complexity and low vertical structure that allows Protestant religious groups, organizations or associations as quickly as possible to implement its social and liturgical practice traditional religious archetype innovations. The article deals with the peculiarities of transformation of social and liturgical practices in the majority of religious organizations and associations registered in the territory of the city of Perm. The analysis of the processes taking place in the religious environment in a large urban agglomeration with a complex structure of religious space shows the presence of transformational changes in the implementation of social and liturgical practices of religious organizations and associations under the influence of self-isolation and a pandemic, despite the conservative conditions of the internal religious environment.

In Ukrainian

The prevalence of Cerium compounds, economic affordability, and unique redox properties determine the wide range of cerium oxide applications. The transition to nanosized particles of cerium oxide allows these materials to reversibly absorb and release oxygen, which determined the use of nano-CeO2 in biomedical technologies in the treatment of diseases associated with lesions due to oxidative stress. The review analyzed the state of modern scientific literature regarding the properties, methods for producing and using cerium nanooxide. The main characteristics of cerium oxide and the features of its structure are described, the mechanisms of action of the enzyme-like properties of nanoceria are given. It was shown that the coexistence of Ce3+ and Ce4+ ions on the surface is compensated by the formation of oxygen vacancies, which are essentially surface defects. Their number depends on the particle size, morphology and crystallinity of the material. These surface defects are catalytic centers that are capable of exhibiting the enzyme-like properties of nanoceria and effectively absorbing free radicals, which include reactive oxygen species. Physicochemical properties of nanoparticles depend on the synthesis parameters. These include the nature and type of precursor, stabilizing agent and solvent, the duration and temperature of the reaction, and the pH of the reactive mixture. So, microgravity affects morphology, average particle size, crystallinity; an increase in the aging time leads to the synthesis of large particles and crystallites, increases the degree of crystallinity. The synthesis temperature affects the size and structure of crystallites, agglomeration, surface defects and oxidation state. Varying the synthesis parameters and their control during the reaction allows one to obtain particles with desired physicochemical properties. The main methods are analyzed in detail: deposition, hydrothermal, microemulsion, combustion, sol-gel and green. It has been established that, due to its unique properties, nanosized cerium oxide has a wide range of applications. It is used as an abrasive powder for polishing glass and protecting it from corrosion; commercial sunscreens are produced on its basis, biosensors and solid oxide fuel cells are constructed, and catalysts are synthesized. Cerium oxide nanoparticles and materials based on it are widely used in environmental, industrial, bioanalytical and biomedical fields. Recently, the biomedical use of nanosized cerium oxide has been rapidly developing. The non-stoichiometric composition of cerium oxide nanoparticles allows it to effectively neutralize reactive oxygen species while protecting the body from oxidative stress. Nano-CeO2 is used in the treatment of inflammatory, cardiovascular and neurodegenerative diseases, it increases the activity of antimicrobials, is an agent for the delivery of therapeutic drugs to cancer cells.

Debris based discharge segregation in reverse micro EDM

Segregation of discharge pulses in micro electrical discharge machining (MEDM) and its variants viz. wire EDM, reverse micro EDM (RMEDM) etc. is mostly carried out on the basis of voltage and current signals. With increase in the machining time, more and more debris accumulate thereby causing abnormal discharges which degrades the machining process. This paper attempts to model discharges in the presence of debris, which hitherto has not been established in literature. Two different simulations were carried out (a) to segregate discharges based on electric field intensity in the presence or absence of debris and (b) to determine the minimum size of debris agglomeration required for a full discharge at increasing machining time where open circuit voltage (OCV) reduces. Based on the magnitude of electric field intensity, the discharge pulses are segregated into three stages: primary or normal discharge without debris, secondary discharge with singular debris particles and higher order discharge in the presence of debris agglomerates. Segregation of discharge pulses in case of experiments is done based on magnitude of voltage which shows that primary discharges dominate initially, however, with increase of machining time, the number of secondary and higher order discharges increase as compared to the primary discharges. A good agreement was established between simulation (segregation of discharges based on magnitude of electric field intensity) and experiments (segregation of discharges based on magnitude of voltage). Moreover, to initiate a full discharge at reduced OCV (higher machining time), a higher size of agglomerated debris is required as compared to the case with rated OCV; wherein full discharge occurs in the absence of debris. The size of agglomerated debris required for initiating a full discharge at lower OCV is very small as compared to the size of actual agglomerated debris, thereby, confirming that number of primary discharges are comparatively lower than the secondary or higher order discharges at higher machining time.

Performance Enhancing of Spray Formed Al/Graphite Alloy Composite by Rolling

The present study outlines the effect of warm rolling on the Al/Graphite alloy composite to investigate its effect on mechanical performance. The Al/Graphite alloy composite has been fabricated by the spray forming process and has been subjected to the rolling at 250 °C with varying reduction. The rolled composite has been studied under different characterization techniques such as X-ray fluorescence (XRF), optical microscopy, scanning electron microscopy with energy dispersive spectroscopy (EDS) and tensile tester. The XRF and EDS results indicate that the Al/Graphite alloy composite is successfully formed. The microscopy results show that the grain size of α-aluminium and agglomeration of the particles refine by rolling and they continuously decrease with an increase in rolling reduction. The strength and percentage elongation of the composite improves by rolling and they continuously increase with an increase in rolling reduction. Further, the fracture surface study has also been performed and it indicates that the fracture of the composite alters from brittle to ductile mode with an increase in rolling reduction. The appeared fracture surface of the composite has also been correlated with the produced microstructure and the tensile properties.

Effect of Co(NO3)2·6H2O thermal decomposition temperature on the nano-Co3O4 product morphology and electrocatalysis of water oxidation

Herein, we report the electrochemical water oxidation efficiency of nano-Co3O4 catalyst samples obtained by the thermal decomposition of Co(NO3)2·6H2O at various temperatures (320, 420, 520, and 620 °C). The structural and morphological details of the synthesized samples were determined by employing X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. These studies revealed the formation of well-dispersed nano-Co3O4 particles with sizes, shapes, and crystallinity levels that differed for the different decomposition temperatures. The prepared catalysts were immobilized on filter-paper-derived carbon electrodes for checking their electrochemical properties. The electrochemical efficiency levels of the Co3O4 catalyst samples were evaluated by employing each of them as an anode to study the water oxidation reaction. The nano-Co3O4 sample prepared at 420 °C yielded the highest efficiency and good stability towards the water oxidation reaction. The higher efficiency of this sample was attributed to the relatively small average size and low level of agglomeration of its nanoparticles, and to the high electrochemically active surface area of its electrode. Different morphology and crystallinity of nano-Co3O4 were prepared by simple and straightforward thermal decomposition of Co(NO3)2·6H2O for electrochemical water oxidation. The nano-Co3O4 prepared at 420 °C showed the highest efficiency and good stability towards water oxidation.

Magnetic properties of NaY1−x−yHoxYby(WO4)2: x = 0.05, y = 0.02 and KY1−x−yHoxYby(WO4)2: x = 0.02, y = 0.01 nanopowders obtained by Pechini and hydrothermal methods

Potassium- and sodium-yttrium double tungstate nanopowders co-doped with Yb3+, Ho3+ ions were investigated for their magnetic properties for the first time. We performed the analysis of the compounds using two methods: Electron Paramagnetic Resonance (EPR) and static Magnetic Susceptibility (MS). We have described the symmetry of doped ions environment and corresponding magnetic, optical and structural properties of the above compounds obtained by hydrothermal and Pechini methods. It was performed for the compounds underwent to different calcination temperatures in the range from 600 °C to 800 °C. For potassium and sodium double tungstates the local symmetry of ytterbium ions is found to be C2 and does not change with the calcination temperature rise. Based on the finite-size effect we determined the relative size of the nanoparticles agglomeration, observing changes in the values of Curie-Weiss temperature and the intensity of the EPR signal for various calcination temperatures. The magnetic and structural properties of nanoparticles were compared to corresponding ones registered for single crystals and crystalline powders obtained using other methods.

The spatial and temporal dimensions of the interdependence between the airline industry and the Chinese economy

The airline industry contributes largely to the economic development of a region. At the same time, the fortunes of the industry can also be affected by regional economic change. This paper uses geographically weighted correlation analysis to investigate the spatial heterogeneity and temporal change of this interdependence as seen in China over the years from 2005 to 2016. The results show that the interdependence between the airline industry and provincial economies is non-stationary, generally with a spatial variation along the east-west axis across China's provinces. Further, the temporal change in the interdependence was affected by specific economic changes, such as the global crisis of 2008, when it weakened. Specifically, air passenger activities in the eastern provinces were more sensitive to some economic changes of 2012, while air freight activities in the western and central provinces were more sensitive to the global economic crisis of 2008. The size of urban agglomeration and regional GDP also influence the spatial heterogeneity of this interdependence with weaker links as GDP increases. It is possible that liberalization of the airline industry could enhance the interdependence in advanced regions. Thus, our results provide significant policy implications for a joint focus on the development of the regional economy and the airline industry.

Combustion synthesis of Ce2LuO5.5:Eu phosphor nanopowders: structure, surface and luminescence investigations

The spherical shape, uniform size and small degree of agglomeration of the particles play crucial roles in promoting the practical applications of the phosphor powders. In this paper, the novel Eu3+ -doped cerium lutetium Ce2LuO5.5 composite nanopowders with a cubic fluorite structure were prepared via a typical solution combustion route, and their internal structure, surface morphology as well as luminescence properties were investigated. The Eu3+ could substitute in either Lu3+ or Ce4+ sites and the existence of oxygen vacancy was confirmed in the composite by X-ray diffraction and Raman spectra techniques. Without the addition of surfactant, most of the as-prepared particles were bound together, and the luminescence was very weak even after a sintering process. Assisted with appropriate polyvinyl alcohol (PVA) surfactant in the combustion reaction and a subsequent heat-treatment process, the bound-particles were evidently separated and seemed to be nearly spherical shape. The particle size could be controlled to 30–120 nm and the luminescence was enhanced by adjusting the subsequent sintering temperature. Excited with 466 nm blue light, the nanopowders exhibited characteristic 5D0 → 7FJ (J = 0–4) emission transition of Eu3+ and showed enhanced red luminescence as Eu3+ occupied Ce4+ site rather than Lu3+ site. The maximum emission was obtained as 40 mol% Eu substitutes Ce in the composite. Due to the coincidence of 466 nm excitation light with the emission of InGaN chips in white light-emitting diodes, the surface-morphology improved Eu-doped Ce2LuO5.5 phosphor nanopowders have a potential application in solid state lighting fields.

ZnS nanoparticles prepared via simple reflux and hydrothermal method: Optical and photocatalytic properties

In this research, zinc sulfide nanoparticles (NPs) with various morphologies such as spherical, flower-like, microspheres decorated with nanoparticles and nanorods were synthesized by two distinct, simple and efficient methods. These approaches include reflux and hydrothermal methods. Zinc nitrate hexahydrate (Zn(NO3)2).6H2O were used as Zn source and thioacetamide (TAA) was used as S source. The effects of TAA to zinc ion mole ratio were investigated on the morphology, particle size, optical and photocatalytic properties of ZnS nanocrystals. In hydrothermal synthesis with increasing Zn2+:TAA mole ratio from 1:1 to 1:2 dendrite-like nanocrystals changed to semi-spherical nanoparticles with average particle size 50–60 nm, with different effect as photocatalysts. But any change at morphology were didn’t observed with changing Zn2+:TAA mole ratio from 1:1 to 1:30 in the reflux method. In the reflux method with increasing in Zn2+:TAA mole ratio, dispersed semi-sphere nanoparticles were observed. The synthesized nanocrystals were characterized by infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy-dispersive x-ray spectroscopy (EDS) and X-ray diffraction (XRD) analysis. XRD analysis and FESEM images show that the size of synthesized ZnS NPs is in the range of 15–25 nm. UV–vis spectra showed that by increasing the amount of sulfur source and increasing the reaction time, λmax shifted towards lower wavelengths, and the band gap was in the range of ~ 3.9–4.8 eV for all of the samples. Also, photoluminescence (PL) analysis showed by increasing particle size and degree of agglomeration, emission intensity (λem) decreased. The photocatalytic activity of the as-prepared samples has been compared for the photocatalyst degradation of reactive blue 21. The sample with low Pl intensity has higher photocatalyst efficiency.

Vacuum freeze-drying assisted preparation of spherical AlB2 powders with ultrafine microstructure

In this paper, we report the preparation of the spherical AlB2 powders with uniform particle size, high crystallinity and free of agglomeration. The spherical powders were fabricated by a facile solid state reaction involving the initial preparation of homogenously mixed elemental reactants via the vacuum freeze-drying method. The obtained AlB2 powders with spherical structure and narrow size distribution showed enhanced sphericity and uniformity when being compared with the ones previously reported. The ultrafine microstructure contributed to agglomerate-free and good flowability, which could efficiently improve its combustion performance. The good antioxidative activity, stable combustion rate and high volumetric heat (53.31kJ/g) made itself as great potential candidate as high-energy density fuel additives.

Rod-Like Rutile Nanoparticles: Synthesis, Structure and Morphology

Nanodispersed rutile with rod-like particles is synthesized by hydrolysis of TiCl4 in hydrochloric acid - ethanol alcohol aqueous solution. It is found that the specific surface area, crystallite size and degree of agglomeration are determined by molar ratio of ethanol in reaction medium. According to HR-TEM images and XRD data rutile crystallites are preferred oriented along the [001] axis. The analysis of the Raman spectra for samples with different morphology is performed. The model of rutile nanorods nucleation and growth is proposed.