Ultrafine Powders Research Articles

Chinese herb ultrafine powder supplementation improves egg nutritional value and quality in laying hens

This study evaluates the effects of dietary Chinese herb ultrafine powder (CHUP) supplementation in late-phase laying hens on the quality and nutritional values of eggs. A total of 576 Xinyang black-feather laying hens (300-day-old) were randomly allocated into eight groups for a 120-day feeding trial. Each group contained eight replicates with nine hens per replicate. The experimental groups included the control (basal diet) and different levels of CHUP groups (details in ‘Materials and methods’). The results showed that the eggshell strength was increased (p < 0.05) in the L, LF, L-LF, L-T, and LF-T groups on day 60 of the trial. In addition, the plasma estradiol level in the L-LF, LF-T, and L-LF-T groups and unsaturated fatty acids concentrations in egg yolk of the CHUP groups (except LF-T group) were increased, whereas total cholesterol (T, L-LF, L-T, and L-LF-T groups) in egg yolk and the atherogenicity (T, L-T, and L-LF-T groups) and thrombogenicity (T, L-LF, L-T, and L-LF-T groups) indexes were decreased (p < 0.05) on day 60 of the trial compared with the control group. Moreover, bitter amino acids in egg albumen were decreased (p < 0.05) in the L-LF group on day 60 and the L-LF-T group on day 120 of the trial. Collectively, these findings indicate that dietary CHUP supplementation could improve eggshell quality and increase plasma reproductive hormone, fatty acid and amino acid composition, and nutritional values of eggs, especially L-LF and L-LF-T.

Interfacial Enhancement and Composite Manufacturing of Continuous Carbon-Fiber-Reinforced PA6T Composites via PrePA6T Ultrafine Powder.

Semi-aromatic poly (hexamethylene terephthalamide) (PA6T) oligomer (prePA6T) ultrafine powder, with a diameter of <5 μm, was prepared as an emulsion sizing agent to improve the impregnation performance of CF/PA6T composites. The prePA6T hyperfine powder was acquired via the dissolution and precipitation "phase conversion" method, and the prePA6T emulsion sizing agent was acquired to continuously coat the CF bundle. The sized CF unidirectional tape was knitted into a fabric using the plain weave method, while the CF/PA6T laminated composites were obtained by laminating the plain weave fabrics with PA6T films. The interfacial shear strength (IFSS), tensile strength (TS), and interlaminar shear strength (ILSS) of prePA6T-modified CF/PA6T composites improved by 54.9%, 125.3%, and 120.9%, respectively. Compared with the commercial polyamide sizing agent product PA845H, the prePA6T sizing agent showed better interfacial properties at elevated temperatures, especially no TS loss at 75 °C. The SEM observations also indicated that the prePA6T emulsion has an excellent impregnation effect on CF, and the fracture mechanism shifted from adhesive failure mode to cohesive failure mode. In summary, a facile, heat-resistant, undamaged-to-fiber environmental coating process is proposed to continuously manufacture high-performance thermoplastic composites, which is quite promising in mass production.

Effect of jet milled ultrafine powder on porous tungsten emitter components by micro injection molding

Micro injection molding (μPIM) is currently the optimal solution for fabricating porous tungsten emitters with complex shapes. Considering the serious agglomeration of ultrafine powder, using this particle size for μPIM is detrimental to the molding of the components and the regulation of the pore structure. In this work, jet milling technology was applied as pretreatment to obtain uniformly dispersed ultrafine tungsten powder, and a needle-like porous tungsten emitter with uniform and adjustable pores was successfully prepared by μPIM. The effects of jet milling on the characteristics of ultrafine tungsten powder and μPIM process were investigated. After the jet milling treatment at 0.75 MPa and 12,000 rpm, the agglomerates in ultrafine powder were completely eliminated and the powder dispersion was optimized. The solid loading of feedstock was increased from 45% to 51%, and the corresponding rheological properties and debinding efficiency were also improved. Jet milled powder exhibited higher sintering activity and gained the same porosity (25%) at 1425 °C, lower than the 1500 °C of the as-received one. The porous tungsten obtained by jet milled powder had pores and skeletons with uniform size and distribution, which contributes to the adjustment of the pores. The pore size decreased from 338 nm to 263 nm, and the closed porosity decreased from 1.5% to 0.6%. This work is beneficial for further understanding the influence of jet milling on powder characteristics, μPIM process and pore characteristics, and highlights its potential application in the field of micro-pores complex parts.

Study on the hydrophobic nano silica particles as flow-enhancing additives for ultrafine dry powder fire extinguishing agent

Sodium bicarbonate-based ultrafine dry powder fire extinguishing agents (UDEAs) exhibit high hygroscopicity and a tendency to agglomerate, which result in poor flowability and diminished extinguishing efficiency, thus proving to be crucial concerns in the UDEA design. The integration of hydrophobic nano silica (HNS) has been recognized as an effective strategy to tackle these challenges, but the precise optimal quantity of HNS in UDEA has been a subject of confusion. Consequently, the impact of HNS as an additive on the flowability of sodium bicarbonate UDEA was thoroughly examined. Through high-speed stirring, the surface of UDEA was evenly coated with HNS particles, resulting in a notable increase in the contact angle of the modified extinguishing agent to approximately 135.4°. Notably, the UDEA formulation with an 8% HNS addition exhibited the least cohesion, the highest flow function value, and the lowest spray resistance. Moreover, the study unveiled the underlying flow mechanism of sodium bicarbonate UDEA influenced by the HNS additive. The findings indicated that the most effective incorporation of HNS into sodium bicarbonate UDEA was 8%, considering both its hydrophobic properties and flow characteristics.

Refining mechanisms of arsenic during preparation process of ultrafine WC powder by nitridation−carbonization method

To simplify the preparation process and prepare ultrafine WC powder, a certain amount of As element was added to the ammonium paratungstate precursor. The mechanism of As in the preparation process of ultrafine WC powder by nitridation−carbonization method was systematically discussed. The results show that when the carbonization temperature was 1400 °C, the nitridation temperature increased from 500 to 600 °C, and the As content increased from 0 to 0.3 wt.%, the average particle size of the prepared WC powder decreased from 2.23 to 0.22 μm, and the particle uniformity was significantly improved. The As element in the nitrided product was in the form of W2O3(AsO4)2, which was easily enriched or distributed between the two phases on the surface of the nitrided products (NH4)0.42WO3 and WN, hindering the growth of WC grains during the carbonization process. Consequently, ultrafine WC powder was prepared.

Synthesis of nano- and ultra-fine refractory carbide powders by low-temperature calcium-carbothermic process and their grain growth during sintering

Metal carbides are widely used in various applications as catalysts, components of composite materials, cutting tools, and abrasive materials where the particle/grain size has a great impact on target properties. Here, we report a facile way to synthesize nano- and ultra-fine carbides of IVb-Vb groups, including high-entropy carbides, which are of interest nowadays due to their superior properties, by the combination of calcium-hydride reduction of metal oxides and the direct reaction of the reduced metals with carbon in one production step. By tailoring the synthesis parameters, it is possible to obtain the carbide powders of a size in the range of 50–1500 nm with high crystallinity. The average particle size is found to be dependent on the homologous synthesis temperature and follows a power law. We have also shown the possibility of obtaining ultrafine-grained bulk carbides (d = 0.24–0.9 μm) via spark-plasma sintering at a temperature of 1500–1650 °C with a relative density >95 % without using additives. The HEC (Ti,Zr,Nb,Hf,Ta)C has a higher activation energy of grain growth (collective recrystallization) compared to binary TaCx (x = 0.8 and 1), which confirms the effect of lattice distortion on diffusion coefficients. The suggested fabrication route can be widely used for nano and ultrafine carbide powder preparation on the industrial scale.

Flavor Characteristics, Antioxidant Activity and In Vitro Digestion Properties of Bread with Large-Leaf Yellow Tea Powder.

Foods containing tea could be widely utilized due to the addition of good tea ingredients, especially large-leaf yellow tea, which is rich with a good flavor. Applying this change to bread containing tea would improve its product quality. In this research, large-leaf yellow tea bread (LYB), possessing a special flavor, was developed using ultrafine large-leaf yellow tea powder and flour as the main raw materials. The amount of ultrafine large-leaf yellow tea powder added to bread was optimized using texture, sensation, and specific volume as comprehensive evaluation indicators. At the optimal dosage, the free amino acids, volatile flavor compounds, antioxidant activity, and in vitro starch digestibility of LYB were measured. Response surface optimization experimental results showed that the comprehensive score of bread was highest when the added amount of ultrafine large-leaf yellow tea powder was 3%. In particular, compared to blank bread (BB), adding ultrafine large-leaf yellow tea powder into bread could effectively increase its amino acid composition, enhance its volatile flavor compounds, improve the antioxidant capacity, and reduce the digestibility of starch.

Influence of Ultrafine Steel Slag Powder Content Upon Cement Mortar

Steel slag (Electric Arc Furnace Steel Slag) is a by-product left over from the conversion of iron to steel in steel industries. This paper reports the results of an experimental study on partial replacement of ordinary Portland cement (OPC) with steel slags powder produced in Libya (Libyan Iron and Steel Company). The effects of various replacement ratios of ultrafine steel slag powder to Portland cement (i.e., 10%, 20%, 30%, 40%, and 50%) on the workability, mechanical, physical and chemical properties were studied. The fineness of steel slag powder was standardized by using a 63 μm sieve. The properties of cement pastes and mortars with ultrafine steel slag powder were tested including water requirement of normal consistency, setting time, soundness, fluidity, dry bulk density, total porosity, water absorption capacity. compressive and flexural strength. The results showed that for cement pastes with ultrafine steel slag powder, the normal consistency water requirement were increased significantly. Both the initial setting time and final setting time were also accelerated than that of the control sample. The partial replacement of cement by ultrafine steel slag powder decreases the compressive and flexural strength, but increases the fluidity which improves the workability of the mortar. The results showed that the optimum content of ultrafine steel slag powder as a replacement of OPC was 10%.

Regulation mechanism of morphology and particle size of ultrafine molybdenum powder prepared via hydrogen reduction of gaseous molybdenum trioxides

In this study, molybdenum powder with desired morphology and particle size was produced through hydrogen reduction of gaseous molybdenum trioxide by changing the hydrogen partial pressure, reaction temperature, hydrogen preheating temperature, and cooling gas flow rate. At the reaction temperature of 1000 °C, the reaction product was a mixture of MoO2 and Mo. The reduction rate reached 100% at 1100 °C, and a further increase in temperature from 1100 °C to 1200 °C caused the average particle size of molybdenum powder to increase from 26.2 nm to 63.1 nm. Both the hydrogen temperature and the cooling intensity during the reaction had a great influence on the nucleation and growth of the grains, respectively. The molybdenum powder obtained without hydrogen preheating exhibited higher nucleation rates and finer grains than those exposed to hydrogen preheating. The molybdenum powder particles evolved from irregular polyhedra to spheres as the cooling intensity decreased through the injection of cooling gas. Therefore, the results of this work provide theoretical guidance for tuning the morphology and particle size of molybdenum powder.

Preparation of ultrafine tungsten powder by fluidized bed hydrogen reduction of WO3-Co3O4

This article investigated the preparation of ultrafine W powder by fluidized bed hydrogen reduction, and the apparent activation energy was determined for various reduction stages by using temperature programmed reduction with hydrogen. The results demonstrate that the introduction of Co3O4 significantly enhances the reduction process of WO3.High Co3O4 content can lead to the formation of CoWO4 in the initial stage and obtain products with high content of Co3W. An increase in the Co3O4 content correlates with a gradual decrease in the particle size of the product. The apparent activation energy for the WO3 → WO2 and WO2 → W processes decreases as the Co3O4 content increases. It can be decreased from 105.59 kJ /mol to 78.72 kJ/mol for the WO3 → WO2 stage, and from 107.38 kJ/mol to 78.38 kJ/mol for the WO2 → W stage, respectively.

Study on the Effect of Ultra-fine Limestone Powder on the Resistance of Cement-slag Powder System to Chloride Ion Permeability

The effect of different limestone powder fineness on the chloride ion migration coefficient of the cement paste was tested using the Rapid Chloride Migration (RCM) method. The changes in the phase composition and pore structure of the paste were studied using hydration kinetics analysis, XRD and pore structure analysis. The results showed that before the chloride ion erosion, the limestone powder mainly exhibited filling effect, microcrystalline nucleation effect, and chemical activity effect. It reacted with the hydration products of cement to form calcium aluminate carbonate, which improved the strength of the hardened paste. After chloride ion erosion, the diffraction peak of calcium aluminate carbonate weakened, and Friedel’s salt was formed. With the increase of the specific surface area of limestone powder, the chemical activity of the powder became more obvious, and the generation of Friedel’s salt increased, leading to stronger resistance to chloride ion penetration. Limestone powder can reduce the porosity of the hardened paste and optimize the pore structure. When the particle size of the powder increased from 800 to 5000 mesh, the total porosity of the hardened paste decreased from 20.7% to 14.7%, and the most probable pore size decreased from 450nm to 75nm. Limestone powder with a particle size larger than 1500 mesh can fully exert its activity and play a role in solidifying chloride ions, thus improving the resistance to chloride ion penetration of limestone powder cement-based materials.

Wear-Resistant Elastomeric Composites Based on Unvulcanized Rubber Compound and Recycled Polytetrafluoroethylene

Advancements in industrial machinery and manufacturing equipment require more reliable and efficient polymer tribo-systems which operate in conditions associated with increasing machine speeds and a lack of cooling oil. The goal of the current research is to improve the tribological properties of elastomeric composites by adding a solid lubricant filler in the form of ultrafine polytetrafluoroethylene (PTFE) with the chemical formula [C2F4]n and recycled polytetrafluoroethylene (r-PTFE) powders. PTFE waste is recycled mechanically by abrasion. The elastomeric composites are prepared by mixing a nitrile butadiene rubber with a phenol-formaldehyde resin and PTFE powders in an extruder followed by rolling. The deformation-strength and tribological tests of r-PTFE elastomeric composites are conducted in comparison with the ultrafine PTFE composites. The latter is based on products of waste fluoropolymer processing using a radiation method. The deformation-strength test shows that the introduction of ultrafine PTFE and r-PTFE powder to the composite leads to a decrease in strength and elongation at break, which is associated with the poor compatibility of additives and the elastomeric matrix. The friction test indicates a decrease in the coefficient of friction of the composite material. It is determined that the 15 wt.% filler added in the elastomeric matrix leads to a reduction in the wear rate by 20%. The results obtained show the possibility of using ultrafine PTFE powder and r-PTFE for creating elastomeric composites with increased tribological properties. These research results are beneficial for rubber products used in many industries, mainly in mechanical engineering.

Ultrafine food powders as clean-label flow additives

The aim of this work was to demonstrate the potential of the concept of clean-label-capable flow additives. These are spray-dried food ingredients whose particle size is small enough (&amp;lt;10 µm) to take over the function of classic flow additives such as highly dispersed silicas. Their acceptance by customers and consumers has been declining for years, as they are primarily mineral excipients that are becoming increasingly unpopular in foods. This poses major problems for the food industry, as many food powders have poor flow properties and handling problems. The idea of clean-label flow additives is to create an alternative to meet consumer demands and industry requirements. Using four different cohesive food powders as examples, the authors demonstrate the effectiveness of this concept. For this purpose, flow additives were prepared from low-concentration solutions in a laboratory spray dryer. Dry particle coating was carried out in a tumbling mixer for 30 min, after which the flow properties of the coated powders were determined using a Schulze Ring shear tester. The results show that a significant improvement in the flowability of cohesive food powders is possible by using these spray-dried flow additives. In addition, an anti-caking effect could be observed. There is still a need for optimization in the production of such flow additives in order to increase their economy and effectiveness. Overall, the concept of clean-label flow additives shows great potential.

Influence of Silane Coupling Agent and Anionic Dispersant on the Dispersion Effect of Silicon Carbide Particles.

Silicon carbide (SiC), as a widely used material, has great properties. To improve the flowability of ultrafine silicon carbide slurry, this study used sodium humate, tetramethylammonium hydroxide (TMAH), and N-(β-monoaminoethyl)-γ-aminopropyltrimethyl(ethoxysilane) (KH792) to modify the ultrafine silicon carbide powder produced by Qingzhou Micro Powder Company. The effects of different modifiers on improving the flowability of ultrafine silicon carbide slurry were investigated by means of viscosity tests, sedimentation experiments, and SEM observations. Their modification mechanisms were investigated by means of zeta potential tests, XPS tests, and so on. In this paper, the initial modification of SiC was carried out with KH792, followed by the secondary modification with anionic and cationic modifiers (tetramethylammonium hydroxide and sodium humate), and the optimal modification conditions were investigated by means of a viscosity test, which showed that the lowest viscosity of the modified SiC reached 0.076 Pa·s and that the absolute maximum value of the zeta potential increased from 47.5 at the time of no modification to 63.7 (maximum values) at the time of modification. This means it has an improved surface charge, which improves dispersion. The adsorption results of the modifier on the silicon carbide surface were also demonstrated by the XPS test results.

Preparation of rhenium nanopowder by a joint reduction method of carbon and hydrogen

Ultrafine powders are crucial for the preparation of high-performance Re-based materials via low-temperature sintering. In this work, a joint reduction method of carbon and hydrogen is proposed to prepare Re nanopowder for the first time. The former carbon black can significantly reduce the particle size of final products, and the latter hydrogen reduction can decrease the contents of carbon and oxygen residues. And the as-obtained rhenium nanopowder is only about 108.6 nm with a slight carbon (0.019 wt%) and oxygen (0.03 wt%). This method is straightforward, easy to implement, low-cost and conducive to the large-scale industrial production.

Effects of Superfine Tricalcium Silicate Powder on the Physicochemical and Mechanical Properties of Its Premixed Cement as a Root Canal Filling Material.

Calcium silicate-based cement is a promising material for filling root canals. However, it has several drawbacks to its clinical application, including difficult operation and low curing strength. In this study, we successfully prepared an ultrafine tricalcium silicate powder and investigated the effects of this ultrafine powder on the performance of the premixed tricalcium silicate cement, including the curing process, setting time, hydration products, microstructure, injectivity, fluidity, and compressive strength. The results demonstrate that the addition of ultrafine tricalcium silicate powder alters the hydration product content and product morphology of the premixed cement. By increasing the content of the ultrafine powder, the injectable property of the cement can be increased to more than 95%, the fluidity can be increased from 18 mm to 35 mm, and the curing time can be shortened from 13 h to 11 h. Notably, the addition of the ultrafine powder greatly enhances the compressive strength of the hardened cement, which increases from 20.6 MPa to 51.0 MPa. These results indicate that altering the particle size distribution of the powder is an effective method for enhancing the physicochemical and mechanical properties of tricalcium silicate cement as a root canal filling material.

A method to synthesize ultrafineTiB2 and ZrB2 powders

In this work, the ultrafine TiB2 and ZrB2 powders were prepared using TiO2, ZrO2, C, B4C, and Ca as the raw materials. The process consisted of steps of carbothermic pre-reduction of oxide, boronization and decarburization reactions in Ca melt, wet leaching as well as deep deoxidation. The pre-deoxidation by carbothermic reduction successfully avoids the problem of evaporation loss of boron source in traditional borothermal reduction method to prepare borides due to the generation of boride oxide. Because of the strong exothermic behavior, the adiabatic temperatures in boronization-decarburization step as well as wet leaching step were calculated, and the results show that these reactions are mild and controllable. Furthermore, it was found that the high oxygen contents in as-prepared TiB2 and ZrB2 powders were resulted from the high temperature and low pH value during water leaching and acid leaching processes. After deep deoxidation at 1673 K in vacuum by mixture of C and B4C, the particle sizes of the final TiB2 and ZrB2 powders were about 200 nm, and the oxygen contents were 1.26 wt% and 0.92 wt%, respectively.

Enhanced Absolute Recovered Energy under Low Electric Field in All-Inorganic 0-3 Nanocomposition Thick Films.

Inorganic thick-film dielectric capacitors with ultrahigh absolute recovered energy at low electric fields are extremely desired for their wide application in pulsed power systems. However, a long-standing technological bottleneck exists between high absolute energy and large recovered energy density. A new strategy is offered to fabricate selected all-inorganic 0-3 composite thick films up to 10µm by a modified sol-slurry method. Here, the ceramic powder is dispersed into the sol-gel matrix to form a uniform suspension, assisted by powder, therefore, the 2µm-thickness after single layer spin coating. To enhance the energy-storage performances, the composites process is thoroughly optimized by ultrafine powder (<50nm) technique based on a low-cost coprecipitation method instead of the solid-state and sol-gel methods. 0D coprecipitation powder has a similar dielectric constant to the corresponding 3D films, thus uneven electrical field distributions is overcome. Moreover, the increase of interfacial polarization is realized due to the larger specific surface area. A maximum recoverable energy density of 14.62Jcm-3 is obtained in coprecipitation thick films ≈2.2 times that of the solid-state powder and ≈1.3 times for sol-gel powder. This study provides a new paradigm for further guiding the design of composite materials.

Influence of guide vane on dispersion of aggregates near the guide vane in a turbo air classifier

Ultra-fine particles are prone to agglomeration, limiting the preparation of ultra-fine powder. The aggregates' disaggregation mechanism is studied, and the proposal of improving the guide vane of a turbo air classifier is contributed to strengthen powder disaggregation based on CFD-DEM coupling and the novel local fluid domain extraction method. The results show the cylindrical tail of guide vane is conducive to the disaggregation, and the powder dispersion near the guide vane is improved. When the inlet air velocity vin is <18 m·s−1, the cylindrical tail of guide vane can significantly improve the powder dispersion. When the cylinder diameter is larger than or equal to 2 mm, the effect of the increase of the cylinder diameter on powder dispersion is significant. However, the increase of cylinder diameter will lead to the increase of energy consumption, so the cylinder diameter should not be too large.

Structural performance and durability assessment of ultrafine powdered concrete in modern buildings

Abstract This paper investigates the impact of various ultrafine powders on the flow characteristics and mechanical properties of concrete, with the aim of enhancing its overall performance. Examine the compressive and flexural strengths of cement, establish distinct matching ratios, and clarify the actual mixing quantity of silica fume and ultrafine powder. Analyze the durability of concrete structures and propose causes for carbonation and formation of concrete. Obtain the durability evaluation indexes, propose the variable weight fuzzy comprehensive judgment method, and establish the durability evaluation system for ultrafine powder concrete buildings. When the on-site test results for reinforcement corrosion, concrete strength, carbonation depth, cracks, and damage degree are added together, the values of each assessment vector of the fuzzy comprehensive evaluation are found. This lets us figure out the bridge’s durability grade. The highest compressive degree was achieved by both ultrafine silica-aluminum material and ultrafine mineral fishery powder at a 20% dosage. The submicron silica material achieved the highest compressive strength with a 40% dosage. In the test and analysis of the ultrafine powder concrete bridge building structure, the fuzzy comprehensive judgment grade is III. That is, there is a certain degree of damage state, and measures must be taken, which is consistent with the field test results.