Nano-sized Powders Research Articles

Preparation of C-S-H seeds from waste glass powder and its effect on early performance of cement paste

This study investigates the hydrothermal synthesis of calcium silicate hydrate (C-S-H) seeds using nano-size glass powder (NGP) derived from siliceous raw materials and CaO as the calcareous precursor. The influence of varying NGP concentrations on the particle size, microstructure, and phase composition of the C-S-H seeds was systematically analyzed. The synthesized C-S-H seeds were subsequently employed as additives to evaluate their effects on the early hydration process and compressive strength development of cement paste. The results indicate that increasing the NGP concentration from 0.2 mol/L to 0.8 mol/L leads to an exponential increase in the median particle size of the C-S-H seeds from 147 nm to 1328 nm and a corresponding morphological transformation from flocculent to granular structures. Additionally, the purity of the C-S-H sample decreased from 74.8% to 54.5% as the NGP concentration increased. The addition of C-S-H seeds can increase the 12h compressive strength of cement pastes by 15.5%–53.5%. This improvement is due to the accelerated early hydration kinetics induced by the C-S-H seeds, which act as nucleation sites, thereby increasing the nucleation and growth rates by 31.4% and 53.2%, respectively.

Analysis of conduction mode in cold energy storage using a tank filled with nanomaterial

The intensification of freezing rates through the incorporation of nano-sized powders and fins through a cold storage unit was examined. The Galerkin method with special meshing was utilized to solve equations, which were based on the supposition of conduction mode dominance. Additives of varying diameters (dp) and three different concentration levels (ϕ) were implemented. The findings are presented through ice front visualization, contour plots, and scalar curves. The computational code demonstrated high accuracy during the validation phase. The results reveal that as the dp increases, the solidification time initially drops by approximately 20 %, then subsequently increases by about 49.45 %. The optimal solidification time of 2951.17 s was achieved with medium-sized powders. Furthermore, an intensification in (ϕ) leads to a significant decrement in freezing time by about 41.43 %, with the most pronounced effect observed for nano-powders with dp = 40 nm.

Crystal Structures and Piezoelectric Properties of Quenched and Slowly-Cooled BiFeO3-BaTiO3 Ceramics.

The BiFeO3-BaTiO3 (BF-BT) ceramics were here prepared through the solid-state reaction of Bi2O3, Fe2O3 and nano-sized BT powders. The crystal structures and piezoelectric properties were investigated in both quenched (AQ) and slowly cooled (SC) 0.7BF-0.3BT ceramics. Prior work has shown that rhombohedral and pseudo-cubic phases coexist in 0.7BF-0.3BT ceramics. In this work, the crystal structure of the pseudo-cubic phase was refined as a non-polar orthorhombic Pbnm phase in the SC sample and as a polar orthorhombic Pmc21 phase in the AQ sample. In addition to a sharp dielectric peak at about 620 °C, corresponding to the Curie temperature of the rhombohedral phase, a broad dielectric peak with strong frequency dispersion and a sharp frequency-independent dielectric peak were observed at around 500 °C in the SC and AQ samples, respectively. We determine that the dielectric anomalies around 500 °C were caused by a relaxor phase transition of the non-polar orthorhombic phase in the SC sample and a ferroelectric-paraelectric phase transition of the polar orthorhombic phase in the AQ sample. The AQ sample showed better ferroelectric and piezoelectric properties than the SC sample. The 0.7BF-0.3BT ceramic slowly cooled in a nitrogen atmosphere showed a well-saturated P-E curve and a similar temperature-dependent dielectric constant as the AQ sample. Our results indicate that large concentrations of oxygen vacancies produce a more distorted polar orthorhombic phase and better piezoelectric properties in the AQ sample than in the SC sample.

Rheological Behavior of SiO2 Ceramic Slurry in Stereolithography and Its Prediction Model Based on POA-DELM.

Ceramic slurry is the raw material used in stereolithography, and its performance determines the printing quality. Rheological behavior, one of the most important physical factors in stereolithography, is critical in ceramic printing, significantly affecting the flow, spreading, and printing processes. The rheological behavior of SiO2 slurry used in stereolithography technology is investigated in the current research using different powder diameters and temperatures. The results present the apparent non-Newtonian behavior. The yielding characteristics occur in all cases. For single-powder cases, the viscosity decreases when the powder diameter is increased. When the nano-sized and micro-sized powders are mixed in different proportions, a more significant proportion of micron-sized powders will decrease the viscosity. With an increase in the nano-sized powders, the slurry exhibits the shear thinning behavior; otherwise, the shear thickening behavior is observed. Thus, the prediction model is built based on the use of the pelican optimization algorithm-deep extreme learning machine (POA-DELM), and the model in then compared with the fitted and traditional models to validate the effectiveness of the method. A more accurate viscosity prediction model will contribute to better fluid dynamic simulation in future work.

Enhancing Li-ion diffusivity of Li1.3Al0.3Ti1.7(PO4)3 through liquid-electrolytes-induced secondary crystallization

Solid electrolytes (SEs) offer promising avenues for improving both the energy density and safety of lithium-ion batteries (LIBs). However, the grain boundary resistance remains a significant hurdle that impact the performance of LIBs, particularly when utilizing SEs in powder form. In this study, we introduce a novel approach to reduce grain boundary resistance in Li1.3Al0.3Ti1.7(PO4)3 (LATP) via secondary crystallization induced by liquid electrolytes (LEs). By immersing nano-sized LATP powders in LiPF6/carbonates LEs, rapid aggregation and recrystallization into bulk micrometer-sized particles occur within minutes under ambient conditions. This secondary crystallization process alters the Li distribution within LATP bulk phase, substantially reducing the grain boundary resistance and enhancing Li-ion diffusivity. Consequently, the assembled LATP-modified commercial LiNi0.89Co0.07Mn0.04O2 cathode using LiPF6 electrolyte delivers a remarkable discharge capacity of 105.4 mAh g−1 at 4C, significantly superior to the bare electrode (44.7 mAh g−1). The recrystallized LATP enhances the transport properties and pathways of Li+ ions within the cathode material, especially at high current densities. Multinuclear and multi-dimensional solid-state NMR analysis reveal that active F− ions released from the hydrolysis of LiPF6 electrolytes act as mineralizing agent, facilitating rapid agglomeration and secondary growth of LATP grains. Our findings underscore the efficacy of secondary crystallization using LEs as a promising strategy for eliminating grain boundary resistance and facilitating fast Li-ion conduction of SEs, thereby advancing LIB performance.

Enhancing Tribological Characteristics of Titanium Grade-5 Alloy through HVOF Thermal-Sprayed WC-Co Nano Coatings by TOPSIS and Golden Jack Optimization Algorithm.

Thermal spray coatings have emerged as a pivotal technology in materials engineering, primarily for augmenting the characteristics related to wear and tribology of metallic substrates. This study aimes to delve into applying High-Velocity Oxygen Fuel (HVOF) thermalsprayed WC-Co nanocoatings on Titanium Grade-5 alloy (Ti64). The coating process, utilizing nano-sized WC-Co powder, undergoes systematic optimization of HVOF parameters, encompassing the flow rate of carrier gas, powder feed rate, and nozzle distance. Experimental assessments via Pin-on-Disc (PoD) tests encompass Loss of Wear (WL), Friction Coefficient (CoF), and Frictional Force (FF). Later, an exhaustive optimization of responses is conductede using the Technique for Order Preference by Similarity to the Ideal Solution (TOPSIS) method and the golden jack optimization algorithm (GJOA). Outcomes show a substantial increase in WL, CoF, and FF with a rise in the carrier gas and powder feed rate. However, with increasing spraying distance of powder, the WL, CoF, and FF tend to lower due to higher bonding, which leads to increased wear resistance. The ideal parametric settings achieved from TOPSIS and GJOA are 245 mm of spray distance, 30 gpm rate of powder feed, and 11 lpm of carrier gas flow rate. The powder feed rate contributes 88.99% to the control action, as seen from ANOVA. The confirmation experiment presents that the WL, CoF, and FF output responses are 42.33, 27.97, and 9.38% less than the mean of experimental data. These results highlight the HVOF process in spraying WC-Co nanocoatings to fortify the durability and performance of Ti64 alloy that can be patented for diverse engineering applications.

Particle size analysis of yellowfin tuna (Thunnus albacares) skin collagen powder using papain-soluble collagen method with varying NaCl concentrations: an experimental laboratory

ABSTRACTIntroduction: The skin of yellowfin tuna (Thunnus albacares) contains high protein, which could potentially be a halal collagen product. Collagen extraction using the papain-soluble collagen method has the advantage of producing a higher collagen yield compared to the acid method. Particle size, one of the physical properties of collagen, plays a crucial role in its efficacy in dentistry. This study aims to analyze the particle size of collagen powder synthesized from Thunnus albacares skin using the papain-soluble collagen method, with varying concentrations of NaCl. Methods: Type of research is an experimental laboratory. Thunnus albacares skin was synthesized by chopping, cleaning, and soaking in a 0.1 M NaOH solution. The extraction process used the enzyme papain and 0.5 M of acetic acid. Samples were divided into four groups, each with different concentrations of NaCL: 0, no NaCL;, 0.9 M NaCl, 1.3 M NaCl, and 1.7 M NaCl. After centrifugation, the samples were freeze-dried. The particle size of collagen powder was measured using a Particle Size Analyzer test tool. The data collected was then analyzed using the Mann-Whitney test. Results: Particle size distributions are as follows: K group (3.36 nm), P1 (1.842 nm), P2 (3.36 nm), and P3 (10.12 nm). There is a significant difference in groups K-P1 and P3, P1-P2 and P3, and P2-P3 (p<0.05). However, there is no significant difference in groups K-P2 (p>0.05). Conclusion: Particle size of this research produced nano-sized collagen powder, with the lowest particle size observed in the 0.9 M NaCl group, measuring at 1.842 nm. The particle size increased in the group without NaCl and in the 1.3 M NaCl group at 3.36 nm, and reached the highest value in the 1.7 M NaCl group at 10.12 nm.

Few-layered graphene/Al-Cu alloy matrix composites: Mechanical, tribological and corrosion properties

Nano-sized graphene incorporated Al-5.5 wt% Cu alloy matrix composites were produced via powder metallurgy. Nano-sized graphene powders obtained via the arc-discharge method were incorporated into Al and Cu powders in varying amounts (0–5 wt%) by applying a high-energy ball milling (HEBM) process for different durations. The consolidated composites were prepared by the succeeding uni-axial pre-compaction and pressureless sintering stages. The as-blended and mechanically alloyed (MAed) powders and bulk composites were comparatively characterized in terms of their physical, thermal, microstructural, tribological, mechanical, and corrosion properties depending on the graphene amount and the duration of mechanical alloying (MA). After 4 h of MA, the starting as-blended powders presented as coarse and discrete particles gained a refined and homogenized microstructure with more equiaxed dimensions. Bulk FLG/Al-5.5Cu (FLG in amounts of 0, 0.5, 1, 2, and 5 wt%) composites are ever-increasing hardness values with rising graphene as 109, 101, 128, 238, and 263 HV, respectively. The compressive strength improved gradually to 495 MPa using graphene up to 1 wt%, though contrary to the high hardness values, a drastic decline was observed by 5 wt% graphene incorporation. Besides, the wear resistance of composites outperformed that of the Al-5.5Cu matrix by incorporating this amount of reinforcement together without a deterioration in the corrosion resistance.

Low-temperature fabrication of conductive SiC ceramics using SiO2-coated SiC nanopowder with Sc2O3 additive by spark plasma sintering

Low-temperature fabrication of conductive SiC ceramics using SiO2-coated SiC nanopowder with Sc2O3 additive by spark plasma sintering

Synthesis of nano-silicon carbide by SiO–C reaction

Carbon black has been successfully converted into silicon carbide by reacting it with SiO vapor at 1500 °C under Ar gas environment. The influence of reaction temperature, duration and Ar gas flow rate on the final product was examined. The structural and microstructural property of synthesized SiC was characterized using X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM). Micrographs of synthesized SiC showed that the final product was an agglomeration of SiC nano-powder of 50–500 nm size and nano-whiskers/fibres having a diameter of 50–500 nm and lengths in 0.1–10 μm depending on Ar gas flow rate. The higher conversion of C into SiC was observed at 1500 °C with Ar gas flow rate ∼250 ml/min.

Synthesis, characterization, and temperature-dependent luminescence of Tb3+-activated and self-activated Sr10(PO4)6Cl2 phosphors

In this work, a series of new nanosized phosphors based on strontium chlorapatite (Sr10(PO4)6Cl2, abbreviated as SrClAp) with varying terbium concentration were synthesized using a modified microwave-hydrothermal method. This study meticulously investigated the impact of Tb3+ concentration and annealing temperature on factors such as crystal purity, particle morphology, photoluminescence, chromatic properties, and the mechanism of thermal quenching.The synthesized phosphors underwent characterization using X-Ray Diffraction (XRD) and scanning electron microscopy (SEM) to verify their crystal structure purity and examine their morphology. Upon near-ultraviolet (NUV) excitation at the 378 nm line, the obtained nanosized powders emitted green light arising from the characteristic 5D4→7FJ (J = 6, 5, 4, 3) transitions of Tb3+ ions. Notably, a broad host-related emission was discernible at 80 K, with its intensity diminishing as the temperature increased. The mechanism governing this host-related emission and the process of its thermal quenching have been proposed. Moreover, a comprehensive exploration of the influence of ambient temperature on the emission of Tb3+-doped SrClAp was undertaken.

PIM-1-assisted structuring of amine-functionalized porous organic copolymer for post-combustion carbon dioxide capture

Capturing CO2 from flue gas of coal-burned power plants has been considered to be a promising technology to mitigate the environmental problems caused by rising level of CO2 at the atmosphere. Amine-functionalized adsorbents, showing impressive CO2 adsorption capability and selectivity even at low CO2 partial pressure, face the challenge of permanent structural changes and performance deterioration due to the irreversibly bonding of SO2, a common impurity of flue gas, particularly under humid condition. Besides, the reported amine-functionalized adsorbents are usually nano-sized powders, impractical for industrial applications. Therefore, the development of efficient, stable, and structured CO2 adsorbents is still an urgent need. Herein, we develop a novel structured mixed-matrix adsorbent (PIM-PP-DETA), using a diethylenediamine-appended porous organic copolymer (PP-DETA, prepared by a copolymerization reaction of dichloro-p-xylene and 4,4′-bis(chloromethyl)biphenyl and a one-step amine grafting process) as main adsorbent and PIM-1 as polymer matrix through a phase inversion process. The as-developed PIM-PP-DETA not only exhibits high CO2 adsorption capacity and outstanding CO2 selectivity over N2, but also shows fast adsorption kinetics and high stability under repeated adsorption-desorption cycling under dynamic flow conditions. Furthermore, PIM-PP-DETA possesses high tolerance towards acidic and moist environments, with CO2 adsorption capacity remained at a relatively high level after SO2 and humid exposure, suggesting its potential usage to post-combustion CO2 capture.

Microstructure Analysis and Powder Bed Fusion of Inconel 738 Powder Materials Mixed with Nano-Sized Ceramic Powders

Powder materials strengthened by oxide dispersion are generally made by in-situ method; direct oxide dispersing in matrix powders during atomization. There is also ex-situ method; oxides dispersing by mixing with matrix powders. In this study powder mixtures (Inconel 738 matrix powder + SiO2 powder + Al2O3 powder) were mechanically manufactured by ex-situ process, a lowenergy ball milling method. Then, specimens of the as-mill powders were manufactured by laser powder bed fusion (L-PBF) method and spark plasma sintering (SPS) process. The microstructures of each prepared specimen were compared according to process variables. SEM, EDS, XRD, and Electron Backscatter Diffraction (EBSD) analyses were applied in this study.

Microwave-Assisted Hydrothermal Synthesis of Nanosheet Layered Hexagonal Spinel Ferrites for Efficient Electromagnetic Wave Absorbing.

A microwave-induced combustion method has been utilized to prepare nanosized powders of hexagonal spinel ferrites using urea and glycine as fuel. The structural and electromagnetic absorption of these products was investigated using X-ray diffraction (XRD). From the (3,1,1) and (1013) peaks in XRD measurements, it was seen that the samples we synthesized were nanosized spinel and y-phase hexagonal ferrite. In addition, Fourier-transform infrared measurements showed that the synthesized samples had high absorption values showing Fe-O, which is between 878 to 4000 cm-1, and metal-oxygen transitions, which are between the 700 and 2500-3000 cm-1 in the spinel and hexagonal phases. From the scanning electron microscope image of the particles, it is seen that they are homogeneous, filled structures with ∼35-40 nm. It appears from vector network analyzer measurements that the synthesized 1.5 mm thick composite materials have very high electromagnetic absorption properties and that these composites can also be used in electromagnetic interference, Wi-Fi applications, and health.

Experimental and numerical assessment of thermal characteristics of PCM in a U-shaped heat exchanger using porous metal foam and NanoPowder

The utilization of Latent Heat Thermal Energy Storage (LHTES) has gained significant attention to address the disparity between energy supply and demand. One of the key advantages lies in the use of phase change materials (PCM). The purpose of this research is to overcome this obstacle by focusing on enhancing the thermal efficiency of an advanced thermal energy storage system specifically designed for solar domestic and industrial application. to overcome this obstacle by focusing on enhancing the thermal efficiency of an advanced thermal energy storage system specifically designed for solar domestic and industrial application. Through computational and experimental studies, a novel and small LHTES system with parallel U-shaped heat exchanger (USHX) has been created and investigated. To improve performance, two approaches are employed: optimizing thermal efficiency by dispersing nano-sized graphite powders into the paraffin material, and/or incorporating metal foams. The PCM is RT35HC, and the hot/cold heat transfer fluid is H2O, which travels via the U-shaped tube. The model incorporates the enthalpy-porosity technique to account for phase change phenomena. After comparing the numerical outcomes with the experiments herein run, data are shown in terms of liquid fraction, temperature evolution, stored energy, and a dimensionless parameter that characterizes the phase change process. The findings suggest that the proposed methods for enhancing heat transfer can enhance the thermal efficiency of systems. The outcomes illustrate that by addition of all methods, reduces the melting time by 13.39 %, 60.77 %, and 71.93 %, when compared to system with pure PCM.

Low temperature phase transition mechanism of amorphous Al-oxalate to nano α-alumina

α-Alumina (α-Al2O3), widely used as a raw material or production in advanced manufacturing industry, has attracted much attention in terms of its preparation temperature. A simple dissolution-evaporation-precipitation process was employed to obtain the amorphous Al-oxalate (AAO) precursor, serving as the starting material for the low temperature preparation of nano α-Al2O3. The crystalline structure and thermal behavior of the AAO were compared with commercially available aluminum hydroxide (Al(OH)3) powder using the X-ray powder diffraction (XRD) instrument, the thermal gravity analysis and differential scanning calorimetry (TG-DSC). The phase transition mechanism of AAO was investigated by the fourier transform infrared spectroscopy (FTIR), transmission electron microscope (TEM), scanning electron microscope (SEM), and 27Al magic angle spinning nuclear magnetic resonance (27Al-MAS-NMR). The DSC results indicated that AAO underwent a phase transformation at 982 °C. The α-alumina diffraction peaks appeared in AAO at 1000 °C, while α-Al2O3 phase was observed for Al(OH)3 at 1200 °C. Furthermore, an absorption peak at 452 cm−1, corresponding to Al–O bond in α-alumina was detected at 1000 °C. The proposed low-temperature preparation mechanism of α-alumina from AAO is as follows: four coordination Al-oxalate species entities coexist within the AAO sample; with increasing temperature, organic acid functional groups oxidize and volatilize, resulting in the formation of tetra-coordinate [AlO4], penta-coordinate [AlO5], and hexa-coordinate [AlO6] atomic groups; these atomic clusters further polymerize to form a structurally dense α-alumina crystal at the nano-scale (∼50 nm) at around 1000 °C. The experimental findings present a novel approach and method for the low-temperature preparation of nano-sized alumina powder. Additionally, a feasible theoretical reference for the low-temperature phase transition mechanism of amorphous Al-oxalate was provided.

Optimization of sintering process to fabricate high-density ultrafine-grained (HfNbTaTiZrW)C ceramic: A comparative study

The fabrication of senary carbide (HfNbTaTiZrW)C was achieved by carbothermal reduction process combined with three different kinds of sintering paths, including conventional single-step sintering (CS) and two kinds of two-step sintering (TSS-1 and TSS-2). It is revealed that the synthesized nanosized powders (∼102 nm) through carbothermal reduction exhibited excellent sintering capability to obtain a high density single-phase solid solution with homogeneous metal cation distributions at macro- and sub-micrometer scales, while atomic-level heterogeneity existed with Zr segregation. Compared to CS samples with bimodal microstructure, the application of two-step sintering significantly reduced the amounts of intergranular pores and (ZrHf)O2, accompanied with grain refinement. In particular, a well-designed TSS-2 route comprising short-term high-temperature followed by low-temperature sintering achieved ultrafine-grained bulk with grain size of 1.44±0.22 μm and excellent mechanical properties of elastic modulus of 480 MPa, microhardness of 23.4 GPa, and fracture toughness of 3.8 MPa·m1/2.

Highly bioactive hydroxyapatite coating made by flame spray technique

This research involves fabrication and characterization of flame sprayed hydroxyapatite (HA) coatings on 316 stainless steel substrates where the desirable structure with high porosity can be obtained. Nano-sized HA powder was synthesized and calcined at 600 °C. The subsequent powder was used as feedstock powder for flame spray technique (FS). In-flight particles of HA were spherical with the range of particle size between 3–37 µm. The average coating thickness was 128 µm and the crystalline phases were a mixture of HA and tricalcium phosphate (TCP). Simulated body fluid (SBF) test showed that HA layer was formed after 7 days. Highly bioactive properties were due to high surface area from rough coating and porous structure, which would be beneficial from the flame spray technique. The coating is promising for applications in biomedical field.

Microstructural and mechanical properties of microwave sintered bulk titanium nitride nanoceramics

In the present work nano-sized TiN powders were consolidated and sintered in nitrogen, argon and air using microwave power of 900 W at frequency 2.45 GHz. Green compacts were exposed to microwave energy, and heated at an in-situ temperature of 1500 °C without holding time. The relative density achieved was ∼92 %. X-ray diffraction analysis showed presence of TiN as the dominant major phase. The microstructures indicate that the sintered samples retained their nanocrystallinty, though aggregates comprising clusters of nanoparticle was noticed with size in the range of 80–400 nm due to high heating rate. Micro indentation assessment indicates average Vickers hardness of 15.2 ± 0.5 GPa. The lengths of cracks originating from the indentation edges were measured; the indentation fracture toughness were obtained between 4.0 and 4.5 MPa.m1/2. The observed properties indicate the suitability of the sintered material in tribological applications.

Preparation of nanohydroxyapatite with diverse morphologies and optimization of its effective aqueous colloidal dispersions for biomedical applications

Hydroxyapatite (HAp) is a bioactive and important material for medical applications. Therefore, search for new possibilities in combining hydroxyapatite with other compounds opens a promising path for creating innovative biomaterials. For this purpose, the preparation of effective aqueous colloidal dispersions based on nanohydroxyapatite (nHAp) of varying degrees of crystallinity and morphology was investigated. Nanohydroxyapatite was prepared by co-precipitation with post-processed freeze-drying, hot-air drying, sintering, and hydrothermal synthesis with tri-sodium citrate. The prepared nanosized powders were analyzed by using X-ray powder diffraction, scanning, and transmission electron microscopy techniques. The influence of post-processing techniques, such as lyophilization, freezing, hot-air drying, and sintering, on the crystallinity and morphology of prepared nanohydroxyapatite suspensions was investigated. Aqueous nanohydroxyapatite colloidal dispersions were prepared using deionized water and tri-sodium citrate solution (0.01 % wt.) with an ultrasonic homogenizer. The study demonstrated that the most effective aqueous colloidal dispersion of nHAp (stable for at least 14 days) can only be obtained using a tri-sodium citrate solution together with freeze-drying. When the material shows higher crystallinity and a more clearly rod-like shape, even tri-sodium citrate does not help maintain the stability of the colloids for a long time. These findings are significant for future investigation involving the preparation of new materials based on nHAp, such as hydrogels, membranes, scaffolds, cement, and composites for biomedical applications. They can be applied in theranostics and drug delivery systems.