Powder Size Research Articles

The Influence of Different Butter Type, Their Fatty Acid Composition and Melting Enthalpy on the Viability Rate of Lacticaseibacillus rhamnosus GG Directly After the Spray-Drying Process and During Storage of Powders

The present work reports on the microencapsulation of Lacticaseibacillus rhamnosus GG (LGG) by the spray-drying process using a solution of starch, whey protein concentrate (WPC), soy lecithin and ascorbic acid as a carrier, with addition of different types of butters. The aim of this study was to examine the protective mechanism of six different butter samples on the viability rate of LGG bacteria directly after the spray-drying process and during storage for 4 weeks at 4 °C and 20 °C (±1 °C) based on hypothetical factors—the fatty acid’s chemical character and content, and its melting enthalpy. The viability of bacteria, moisture content, water activity, color properties, morphology, particle size of powder, melting enthalpy of butters and their fatty acids composition were evaluated. It is assumed that the highest viability may be indirectly influenced by the relationship between the highest content of proteins and sugars and the lowest content of fats and fatty acids, which is characteristic for butter with a reduced fat content. This butter contained also the least monounsaturated and polyunsaturated fatty acids. The highest number of viable LGG (for systems with reduced-fat butter, as well as salted and lactose-free butter) may be caused by (among other factors) by the lower content of palmitic acid (C16: 0). For these butters, it was also observed that cell viability increased with the increase in melting enthalpy. The results confirmed the protective role of selected butters, which indicates the possibility of using them in industrial processes to increase the durability of additives and products using probiotic powders obtained by spray-drying.

Tensile Properties of Ex-Situ Ti-TiC Metal Matrix Composites Manufactured by Laser Powder Bed Fusion.

Titanium-based Metal Matrix Composites (MMCs) manufactured by additive manufacturing offer tremendous lightweighting opportunities. However, processing the high reinforcement contents needed to substantially improve elastic modulus while conserving significant ductility remains a challenge. Ti-TiC MMCs fabricated in this study reported fracture strains in tension up to 1.7% for a Young's modulus of 149 GPa. This fracture strain is 30% higher than the previously reported values for Ti-based MMCs produced by Laser Powder Bed Fusion (LPBF) displaying similar Young's moduli. The heat treatment used after the LPBF process leads to the doubling of the fracture strain thanks to the conversion of TiCx dendrites into equiaxed TiCx grains. The as-built microstructure shows both un-dissolved TiC particles and sub-stoichiometric TiC dendrites resulting from the partial dissolution of TiC particles. The reduction of the C/Ti ratio in TiC during the process results in an increase in the reinforcement content, from a nominal 12 vol% to an effective 21.5 vol%. The variation of the TiC lattice constant with its stoichiometry is measured, and an empirical expression is proposed for its effect on TiC's Young's modulus. The lower TiC powder size distribution displayed higher mechanical properties thanks to a reduced number of intrinsic flaws.

Properties of Al0.5CoCrFeNi2Ti High-Entropy Alloy System: From Gas-Atomized Powders to Atmospheric Plasma-Sprayed Coatings

AbstractThe performance of the Al0.5CoCrFeNi2Ti HEA atmospheric plasma-sprayed coating was extended from characterizing the properties of its powder prepared via the gas atomization method. It was observed that the gas-atomized HEA powders possessed a solid solution BCC phase, while a major phase transformation to a FCC-L21 intermetallic phase occurred during the annealing process. The formation of the intermetallic phase resulted in an increase in average hardness from 6.28 to 7.64 GPa after annealing at 900 °C for 1 h. Afterward, HEA powders were applied in the atmospheric plasma spray technology. The phase constitution of Al0.5CoCrFeNi2Ti HEA coatings was investigated by varying powder size and applied current. It was observed that the smaller powder sizes prone to oxidation, whereas higher applied current facilitated the phase transformation from BCC to FCC phase. The nanoindentation test indicated distinct average microhardness values for the interlamellar oxide region, BCC unmelted particle and FCC phase lamellar region, which was measured at 12.35, 8.68 and 5.97 GPa, respectively. As a result, the adjustability of coating hardness was achieved by manipulating the relative phase ratio.

Enhancing mortar performance: A comparative study on particle size of recycled concrete powder and metakaolin in binary and ternary blends

The construction industry generates substantial volumes of construction and demolition waste (CDW), including aggregates and fine particles classified as recycled concrete powder (RCP). This study investigates the sustainable reuse of RCP by evaluating its combined use with metakaolin (MK) as supplementary cementitious materials in both binary and ternary mixtures with Portland cement, aiming to reduce environmental impact without compromising mortar performance. The experimental program assessed two particle sizes of RCP, along with MK, and various replacement levels, which were pivotal parameters in the study. A series of binary and ternary mixtures were prepared with different proportions of RCP and MK, considering replacement levels ranging from 10 % to a maximum of 30 %, using RCP alone or in conjunction with MK. The mortars were analyzed in both fresh and hardened states, focusing on critical properties such as consistency index, compressive strength, splitting tensile strength, elastic modulus, water absorption, density, void index, and capillary water absorption. Furthermore, a microstructural analysis was conducted using scanning electron microscopy (SEM), and a cement consumption efficiency index, along with CO₂ emissions data, was calculated to provide a comprehensive evaluation of performance and sustainability. The findings demonstrate that RCP with a particle size comparable to that of cement (RCP1) significantly enhances both physical and mechanical performance, particularly in ternary mixtures with MK due to its pozzolanic activity, where the silica (SiO₂) and alumina (Al₂O₃) components react to form additional hydrated products, thereby improving the properties of mortars. For instance, the ternary mixture comprising 15 % RCP1 and 15 % MK attained compressive and splitting tensile strength of 29.26 MPa and 3.36 MPa at 28 days, respectively, compared to the reference mixture, which yielded 27.96 MPa and 3.33 MPa. Conversely, larger particle sizes (RCP2) and higher replacement levels led to a decline in performance across all evaluated parameters. Ternary mixtures containing RCP1 also exhibited a higher cement consumption efficiency index and lower CO₂ emissions per MPa. Notably, the mixture with 15 % RCP1 and 15 % MK showed the most favorable indicators overall, with cement consumption and CO₂ emissions measured at 12.08 kg/m³·MPa and 10.01 kgCO₂/m³·MPa, respectively. These results suggest that the synergy between RCP1 and MK enhances particle packing and matrix density, which in turn improves the structural properties of the mortar. The incorporation of MK compensates for the limited reactivity of RCP, especially at higher replacement levels, while the utilization of RCP1 offers significant sustainability benefits by reducing Portland cement consumption. This study demonstrates that the combination of RCP and MK in ternary mixtures presents a technically viable and sustainable alternative for mortar production, optimizing cement use and reducing CO₂ emissions. The innovative application of CDW-derived RCP in construction materials represents a practical approach to promoting more sustainable practices within the industry.

Phase transformation mechanism and microstructure of a Y-doped TiAl gas-atomized powders

In this study, the phase transformation mechanism of a yttrium-containing β-solidified TiAl alloy (Ti-43Al-9 V-0.3Y at.%), prepared by gas atomization, was systematically investigated. X-ray diffraction, electron backscatter diffraction, scanning electron microscopy, and transmission electron microscopy were utilized to comprehensively analyze the morphology and microstructure of powders with varying sizes as well as the form and distribution of yttrium and its influence on the phase transformation of the powders. The results show that the solidification phase structure of the powders exhibits significant variations: the ultra-fine powder consists of α’ martensite and remaining β phase, while the medium-sized powder is solely composed of β0 phase. The large-sized dendritic powder comprises β0, α’ martensite and α2 phase. With an increase in powder size, there is a corresponding increase in the content of α2 phase, whereas the content of martensite initially rises and subsequently declines. Additionally, yttrium is present in the form of multiscale Y-rich precipitates (YAl2 and Y2O3) within the matrix, and the segregation degree gradually increases with increasing powder size. The primary factors contributing to the disparity in solidification structure include cooling rate and segregation defects. A faster cooling rate and a higher supercooling degree will inhibit the β → α transition, while the Y-rich precipitated phase forms a pre-existing strain zone around it, providing an effective site for martensitic nucleation. In summary, these findings offer novel insights into the mechanism of phase transformation in yttrium-containing β-solidified TiAl alloy, thereby contributing to further advancements in the theory of rapid solidification for TiAl alloys.

A room temperature chemical process for homogeneous mixing of precursor phases for low temperature tetracalcium phoshate preparation

The aim of this study was to prepare phase pure tetracalcium phosphate (TTCP) from the precursor phase mixtures homogeneous at the nano/microscale level at lower heat treatment temperatures in much shorter dwell times.Two different precursor powder mixtures were prepared by reacting CaCO3 with H3PO4 in ethanol or water. The resultant precursor powder mixtures were heat treated at temperatures in the 1200–1350 °C range for 2 and 5 h. Phase structures of the powders were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Raman spectroscopy analysis. Scanning electron microscopy (SEM) was used for the investigation of powder particle sizes and morphology. Powders synthesized by the heat treatment of both of the starting powder mixtures prepared in ethanol or water with 2 and 5 h of dwell times at 1350 °C were determined to be phase pure TTCP. SEM analysis along with the phase identification showed that the precursor powder prepared in ethanol had micron sized plates formed by aggregation of sub-micron sized thin CaHPO4 plates covering CaCO3 particles. The precursor powder prepared in water contained large aggregates of sub-micron sized CaCO3 particles whose surface was covered by precipitated nano-sized hydroxyapatite. TTCP powders were composed of large irregularly shaped particles formed by sintering of smaller equiaxed grains. Average grain and particles sizes of the TTCP powders synthesized from the precursor powder prepared in ethanol were 3.2–3.9 and 8.1–8.4 μm, respectively. Average grain and particle sizes of the TTCP powders synthesized from the precursor powder prepared in water however were measured to be 3.3–5.1 and 11.2–11.6 μm, respectively.The TTCP preparation method presented in this study provides homogeneous and well-mixed precursor powders prepared from cheap and commonly available precursors without milling and decreases the heat treatment time to 2 h at 1350 °C.

The Use of TiH2 to Refine Y2Ti2O7 in a Nano Mo-ODS Alloy

Mo-ODS alloys have excellent mechanical properties, including an improved recrystallization temperature, greater strength due to dispersed oxides, and the ability to suppress grain growth at high temperatures. In ODS alloys, the dispersed Y2O3 and added Ti form Y-Ti-O complex oxides, producing finer particles than those in the initial Y2O3. The complex oxides increase high-temperature stability and improve the mechanical properties of the alloy. In particular, the use of TiH2 powder, which is more brittle than conventional Ti, can enable the distribution of finer oxides than is possible with conventional Ti powder during milling. Moreover, dehydrogenation leads to a more refined powder size in the reduction process. This study investigated the refinement of Y2Ti2O7 in a nano Mo-ODS alloy using TiH2. The alloy compositions were determined to be Mo-0.5Ti-0.5Y2O3 and Mo-1.0Ti-0.5Y2O3. The nano Mo-ODS alloys were fabricated using Ti and TiH2 to explore the effects of adding different forms of Ti. The sintered specimens were analyzed through X-ray diffraction for phase analysis, and the microstructure of the alloys was analyzed using scanning electron microscopy and transmission electron microscopy. Vickers hardness tests were conducted to determine the effect of the form of Ti added on the mechanical properties, and it was found that using TiH2 effectively improved the mechanical properties.

Experimental and Statistical Analysis of Iron Powder for Green Heat Production

In the current investigation, a novel methodology was employed to assess iron powder as a recyclable and sustainable energy carrier. Concurrently, an examination of the modeling of iron powder ignition and the ensuing heat output from the burner was undertaken. The flame temperature was determined by examining the light intensity emitted by the particles as they melted, which is directly related to the particle’s cross-sectional area. An account of the characterization of the experimental procedure, validation, and calibration is presented. Through measurements, distinct one-to-one correlations have been established between the scales of flame combustion and the temperatures of particles of varying sizes of iron. Additionally, a theoretical model for the combustion of expanding particles, particularly iron, within the diffusion-limited regime has been rigorously developed. This model delves into the spectra acquired from particle flames within the burner, utilizing Partial Least Squares Regression (PLSR) and Principal Component Analysis (PCA). This study investigates the use of optical fiber spectroscopy to predict flame temperature and assess iron powder size. The aim was to investigate how different sizes of iron powder affect flame temperature and to create calibration models for non-destructive prediction. The study shows that smaller particles had an average temperature of 1381 °C while larger particles reach up to 1842 °C, demonstrating the significant impact of particle size on combustion efficiency. The results were confirmed using advanced statistical methods, including PLSR and PCA, with PCA effectively differentiating between particle sizes and PLSR achieving an R2 value of 0.90 for the 30 µm particles.

An investigation into the effect of CoCrMo powder characteristics on the powder bed density in laser-based powder bed fusion units

PurposeThe increased use cases for laser powder bed fusion (LPBF) in the research and commercial domains necessitate a better understanding of the inputs and the processing parameters. Porosity in parts manufactured by LPBF could lead to premature failure and increased cost. The powder bed, which is selectively laser melted, must be as densely packed as possible to ensure high-density parts. This paper aims to identify and qualify the variables that affect the packing density of the powder bed.Design/methodology/approachSix different independent variables that affect the packing density of the powder were identified and quantified. The chemical composition, true powder density, powder size distribution, powder circularity and convexity and powder morphology were studied. A powder bed density capsule was printed in place to determine the actual powder bed density in the LPBF unit.FindingsParticle size destitution is the most critical aspect of the packing density in the LPBF unit. Powder with better circularity, convexity and higher powder density has proven to pack less densely than powder with many smaller particles. A more significant number of fine particles will ensure the voids between larger particles are filled, and a denser item, with less porosity, can be manufactured.Originality/valueThe independent variables quantified in this study to determine their effect on the packing densities are discussed. Adherence to the ASTM standard applicable to this industry is discussed, and the quantification method is evaluated. This work’s original contribution is identifying the effect of the ratio of D90 to D10 values based on particle diameter and its interaction within the LPBF unit to result in the highest possible packing density.

White mulberry leaf (Morus alba L.) infusion as a strategy to reduce starch digestibility: The influence of particle size of leaf powder

Mulberry leaf (Morus Alba L.) has been found in clinical trials to be effective in reducing diabetes in Asia. The powdered tea market is expanding in popularity due to its functional properties. This study aimed to examine the influence of different particle sizes of mulberry leaf powder (MLP) infusion on the digestibility of starch in cooked Japonica rice (cv. Koshihikari) and the bioaccessibility of phytochemicals. Dried mulberry leaf was pulverized and sieved into several particle sizes: 160 μm (MLP160), 250 μm (MLP250), 404 μm (MLP404), and 774 μm (MLP774). Through simulated in vitro digestion, we assessed starch hydrolysis (%SH), the kinetics of starch hydrolysis, estimated glycemic index (eGI), as well as total phenolic content (TPC) and total flavonoid content (TFC). The smaller particle size of MLP showed a greater reduction of eGI. Specifically, infusions prepared from MLP160 resulted in a reduction of 15 % in eGI for cooked grains and 3 % for slurries, respectively. The reduction in eGI was attributed to the interaction among flavonoids and digestive enzymes, demonstrating a concentration-dependent manner on enzyme inhibition effect. Pulverization significantly influenced the concentration of phytochemicals and their bioaccessibility in infusions. This study offers valuable insights into determining optimal particle sizes for MLP, considering both physical and functional characteristics as well as implications for the food industry. The results further suggest that MLP infusion holds promise as a functional beverage, potentially providing benefits in reducing postprandial hyperglycemia.

Development of Bamboo Based Nylon 66 Composite through Friction Stir Processing-An Attempt

The concept of developing a bamboo-based Nylon 66 polymer matrix composite is a relatively novel and very new technical attempt through friction stir processing (FSP). This innovative approach can create a composite material that strengthen the mechanical properties of bamboo and the versatility of Nylon 66. However, successful implementation requires careful consideration of FSP process parameters such us tool rpm, traverse speed, tilt angle and tool design. Among the processing parameters, the tool rpm shows the significant role for severe plastic deformation and temperature generation which leads to the achieving excellent bond. Therefore, in this present study attempt has made to develop the polymer matrix composite (nylon 66 and bamboo powder) using FSW process at a variant rotational speed of 300,400 and 500 rpm with the constant traverse speed of 25 mm min-1. The deformation behavior and the peak temperature evolved under the tool shoulder during the stirring motion is studied using COMSOL Multiphysics simulation. It is found that, the specimen processed with higher rpm (500rpm) shows the higher volumetric strain and the peak temperature and it is evident that with increasing rpm the higher amount of severe plastic deformation occurred. Initially the process parameters are optimized without bamboo powder on the nylon 66 plate of 6 mm thickness and found that the 500 rpm processed specimen shows the defect free. Prior to the actual FSP, the small keyways taken on the center of the nylon 66 plate in order to add the bamboo powders in it. Actual processing was done with bamboo powder after adding natural bamboo powder of size 50µm. The result reveals that, the bamboo powder has partially expelled out during the period of FSP. This complete study concedes that the processing parameters needs to be optimized and also bamboo added method need to be studied for the successful development of bamboo-based polymer matrix composite.

Response tests on the effects of particle size of waste glass sand and glass powder on the mechanical and durability performance of concrete

To investigate the effect of waste glass material particle sizes on the mechanical and durability properties of concrete, a two-phase experimental approach was conducted. First, comprehensive tests were performed to examine the effects of glass sand and glass powder of different particle sizes on concrete performance. Subsequently, based on the experimental results, an orthogonal test was designed to optimize the replacement amounts of composite particle sizes. The results indicated that an appropriate amount of glass sand can enhance the mechanical properties and durability of concrete, while excessive amounts or larger particle sizes may have adverse effects. The pozzolanic effect of glass powder also contributes to performance improvement, but the replacement rate should be limited to 20%. Under composite particle size conditions, the compressive, tensile, and shear strengths of concrete increased by 35.56%, 21.74%, and 13.79%, respectively, while durability significantly improved, with water absorption reduced by 20.73% and chloride ion permeability decreased by 63.10%. At a total replacement rate of 20%, the optimal proportions were determined to be 2.86% for 0.6 mm glass sand, 1.43% for 1.18 mm glass sand, 8.57% for 50–60 μm glass powder, and 7.14% for 60–70 μm glass powder. The incorporation of composite particle sizes improved the microstructure of concrete, thereby enhancing its mechanical and durability properties.

Predicting Lightweight Powders with Useful Sound Absorption Characteristics from Their Specifications

Powders that absorb sound by longitudinal vibration have either a gentle or sharp sound absorption curve at the first absorption peak frequency. Experiments were performed to investigate the conditions under which longitudinal vibration occurs in powders of various grain sizes and bulk densities. The sound absorption characteristics of the powders were then classified according to their specifications, and the sound absorption coefficients predicted by derived empirical equations were compared with the measured sound absorption coefficients. A threshold value for the areal density per grain layer was identified where lightweight powders at 0.0006 g/cm2 or less demonstrated useful sound absorption characteristics via longitudinal vibration. Powders with smooth (i.e., useful) and sharp (i.e., not useful) sound absorption curves could be further identified by the half-width value at 0.0974 < log f2 − log f1 < 0.119 decade. The bulk density can also be used to identify powders with useful sound absorption characteristics at 0.0868 < ρ < 0.124 g/cm3. A regression analysis was performed to obtain empirical equations expressing the relationship between the areal density per grain layer and first sound absorption peak frequency normalized by the layer thickness.

Preparation and excellent mechanical properties of nanocrystalline GW103K Mg alloy by HDDR technology

Grain size of GW103K Mg alloy powder were markedly refined to about 45 nm from 20 μm by an optimized hydrogenation-disproportionation-desorption-recombination (HDDR) process. By changing temperature, hydrogen pressure and time, the optimum hydrogenation conditions are explored by orthogonal design. Then the complete dehydrogenation process was determined by using single factor control variables. Furtherly, the HDDRed powder was spark plasma sintering (SPS) sintered and hot extruded to prepare GW103K alloy bulk. XRD, OM, scanning electron microscopy (SEM), and transmission electron microscope (TEM) were used to analyze the phase transformation and microstructure evolution, based on which the grain refining mechanism during the HDDR were discussed. The optimum HDDR parameters for preparing nanocrystalline Mg alloy powders are hydriding at 550 °C under 5 MPa hydrogen pressure for 24 h and dehydriding at 550 °C for 8 h in vacuum. The nanocrystalline GW103 alloy presents a notable dimensional stability and the grain size of the alloy bulk is 43 nm after SPS and hot extrusion. As a result, the nanocrystalline GW103K specimens exhibit excellent mechanical properties compared to the coarse-grained counterparts. Especially, the nanocrystalline GW103K alloy has a tensile elongation of 21.1% which is much more than those of the as-cast and as-extrusion alloys.

Synergistic impact mechanism of particle size and morphology in superalloy powders for additive manufacturing

The particle size and morphology of superalloy powders are crucial parameters that significantly influence the performance of additive manufacturing (AM) processes. This study investigates the effects of atomization pressure on these characteristics through a combination of computational fluid dynamics (CFD) simulations and vacuum induction melting gas atomization (VIGA) experiments. The CFD simulations revealed that increasing the atomization pressure from 2.0 MPa to 3.5 MPa resulted in a rise in maximum gas velocity from 526 m/s to 537 m/s and a reduction in median particle size (D50) from 60.9 μm to 37.5 μm. Subsequent experiments demonstrated a decrease in D50 from 52.9 μm to 35.6 μm, and sphericity from 0.9432 to 0.9377, as pressure increased. The particle size results of the atomization experiments and numerical simulations show strong consistency, validating the accuracy of the numerical simulation results. The volume of hollow particles also increased slightly in specific size fractions. These results suggest that higher atomization pressures produce finer powders with lower sphericity, but also promote particle adhesion, reducing the overall refinement effect. This study provides insights into optimizing atomization conditions for the precise control of superalloy powders in AM.

Dissolution of Volcanic Ash in Alkaline Environment for Cold Consolidation of Inorganic Binders.

A systematic study on the dissolution in concentrated alkali of two volcanic ashes from Cameroon, denoted as DAR and VN, is presented here. One volcanic ash, DAR, was 2 wt% richer in Fe and Ca and 4 wt% lower in Si than the other, designated as VN. Such natural raw materials are complex mixtures of aluminosilicate minerals (kaersutite, plagioclase, magnetite, diopside, thenardite, forsterite, hematite, and goethite) with a good proportion of amorphous phase (52 and 74 wt% for DAR and VN, respectively), which is more reactive than the crystalline phase in alkaline environments. Dissolution in NaOH + sodium silicate solution is the first step in the geopolymerisation process, which, after hardening at room temperature, results in solid and resistant building blocks. According to XRD, the VN finer ash powders showed a higher reactivity of Al-bearing soluble amorphous phases, releasing Al cations in NaOH, as indicated by IPC-MS. In general, dissolution in a strong alkaline environment did not seem to be affected by the NaOH concentration, provided that it was kept higher than 8 M, or by the powder size, remaining below 75 µm, while it was affected by time. However, in the time range studied, 1-120 min, the maximum element release was reached at about 100 min, when an equilibrium was reached. The hardened alkali activated materials show a good reticulation, as indicated by the low weight loss in water (10 wt%) when a hardening temperature of 25 °C was assumed. The same advantage was found for of the room-temperature consolidated specimens' mechanical performance in terms of resistance to compression (4-6 MPa). The study of the alkaline dissolution of volcanic ash is, therefore, an interesting way of predicting and optimising the reactivity of the phases of which it is composed, especially the amorphous ones.

Damaging effect of fine grinding treatment on the microstructure of polyurea elastomer modifier used in asphalt binder

The excellent elasticity and strength of polyurea elastomer could provide good potential in asphalt modification. In this paper, PUA materials were prepared by spraying and crushing technology. Using liquid nitrogen, PUA was ground into powders of different particle sizes. The size composition and characteristics of PUA powder were analyzed using laser particle size analyzer. The functional microstructures were identified through laser confocal scanning microscopy. The damaging effect of grinding on functional microstructures was investigated. The impact of PUA on the rheological property of asphalt was determined. The results showed that the size distribution of PUA powders presents the normal distribution characteristic, and the size distribution of 0.3 mm, 0.15 mm, and 0.075 mm PUA powders have intersection. The spherical microstructure distributed independently in PUA particle and some spherical microstructure distributed in the triangular shape. The width/length ratio of characteristic microstructure in 0.15 mm and 0.075 mm PUA powder were increased, which supposed that the spherical microstructure had been damaged by grinding effect. PUA could reduce the cumulative deformation of asphalt when suffering from repeated loads.

Effect of milling time on structural and electrical properties of thermomechanically synthesized of Ba0.1 (Bi0.45Na0.45)TiO3 nanoceramics for ferroelectric random-access memory device

Lead-free Ba0.1(Bi0.45Na0.45)TiO3 (BBNTO) nanoceramics were synthesized using high-energy ball milling, followed by a solid-state reaction method. XRD analysis of the microstructure indicated the formation of tetragonal symmetry. The crystallite size of the nanoceramic powder decreased from ∼ 28 nm to 10 nm after milling for 0, 30, 60, and 90 hours. The dielectric properties of the nanoceramics showed significant improvement, with a diffuse phase transition occurring around 80 °C). The dielectric constant increased with temperature across various frequencies, reached a maximum value at approximately at temperature ∼ 380 °C. At lower temperatures and higher frequencies, the relative permittivity and tangent loss depend on the crystallite size and milling duration. Impedance spectroscopy data analysis revealed size-dependent impedance characteristics and dielectric relaxation. The ac conductivity plot adhered to the Arrhenius relation, and the calculated activation energy confirmed the negative temperature coefficient of resistance (NTCR) behavior. P-E loops confirmed ferroelectric properties, indicating potential for use in future ferroelectric-based storage devices.

Complexation mechanism and adsorption modes of Cu (II) ions by wool keratin powder

The excessive presence of Cu (II) ions in wastewater has led to various health problems. Using wool keratin powder adsorbent, the adsorption of Cu (II) ions in wastewater was explored. The adsorption mechanism and efficiency of keratin powder towards Cu (II) ions were characterized by infrared spectroscopy, x-ray diffraction and scanning electron microscopy. The results indicate that the particle size of keratin powder has a significant impact on its adsorption performances. Keratin powder with smaller particle size has more adsorption sites, larger specific surface area, higher porosity and more effective adsorption capacity. After adsorption of Cu (II), the average diameter of keratin powder increased by 11.48 μm. The adsorption capacity reached 58.95 mg g−1, and the adsorption efficiency reached 99.52% after 12 h of contact time. The research results not only provide an effective solution for Cu (II) ion pollution in wastewater, but also explore the resource utilization of waste wool.

Investigation on the Effect of Energy Release Rate of Aluminized Explosive on the Damage of Underwater Targets

AbstractAs a type of high‐energy explosive, aluminized explosives are extensively used in underwater weapons and ammunition. This study aims to investigate the energy release rate on the damage of underwater targets caused by aluminized explosives (RDX/Al). The ship was selected as a target, and numerical simulations were conducted using AUTODYN software to study the energy release rate corresponding to different particle sizes of aluminum powder (25 nm −300 μm) in the underwater explosion process of RDX/Al, as well as its destructive effect on targets in the water. The research quantitatively evaluates the whole ship′s destruction results, including longitudinal bending deformations and crevasse. In addition, typical cabins were selected in this study to assess the local damage effects by analyzing stress, shock wave pressure, displacement, and acceleration shock response. Based on the damage results, it was revealed that RDX/Al with aluminum powder particle sizes ranging from 54 nm to 145 nm exhibited the most optimal damaging effects on ships after underwater explosions. These findings provide a basis for improving the destructive power of aluminized explosives against underwater targets, simultaneously, they can be utilized by ship designers to guide research and development of improved protective measures, aiming to reduce the vulnerability of ships to explosive attacks.