Nano-sized Additives Research Articles

Solidification process modeling for energy storage by means of galerkin method utilizing nano-sized additives

In this study, a numerical method for modeling the freezing process inside a storage enclosure equipped with ψ-shaped fins has been scrutinized. The container features both square and sinusoidal walls, with ψ-shaped fins enhancing the thermal conduction within the system. Alumina nanoparticles, in both blade and cylindrical forms, have been dispersed in the water to investigate the effect of particle shape on the freezing process. The shape factor (m) is considered in the calculation of conductivity to capture the impact of different nanoparticle geometries. Additionally, a single-phase model is used for the nanomaterial formulation, with nanoparticle concentrations (φ) kept below 0.04 to ensure accurate representation. The results reveal that increasing (m) leads to a reduction in solidification time by approximately 7 %. When nanoparticles are dispersed in water, the time required for complete freezing decreases from 275.57 s to 201.95 s, representing a significant improvement. This demonstrates that the presence of nanoparticles can accelerate the freezing process by about 26.71 %. By incorporating ψ-shaped fins and optimizing nanoparticle characteristics, the study provides valuable insights into enhancing thermal conduction and reducing freezing times.

Method for introducing carbon nanotubes into fine-grained concrete

This work discusses the use of a modifying complex additive to concrete with the inclusion of carbon nanotubes “Taunit-M” and the SP-3 plasticizer. Two methods of introducing nano-sized additives into the composition of fine-grained concrete, as well as their combination, are considered. The results of a series of tests of beam samples aged 28 days are presented using two methods of introducing nanotubes, namely: the use of an ultrasonic dispersant and the use of a linear induction rotator (LIR). The positive effect of introducing nanotubes on the strength characteristics of concrete has been established. It has been determined that the use of LIR technology provides an increase in strength due to a double effect: activation of the cement binder and distribution of the nanoadditive using active mixing due to vortex action. Ultrasonic dispersion, in turn, ensures the effective introduction of the plasticizer into the mixing water.

Numerical modeling of physical behavior of PCM in attendance of nano-sized additives

Numerical modeling of physical behavior of PCM in attendance of nano-sized additives

Adsorption and nucleation mechanism of molten carbonate on nano-SiC surface

Molten carbonate is an important thermal storage media for high temperature thermal energy storage system. However, the specific heat capacity (SHC) of carbonate is less than 2 J/g K, which limits its application prospects. Nano-SiC was used to improve the SHC of carbonate at high temperature in our previous work. The SHC of binary carbonate increased by 83 % with the addition of nano-SiC. However, the improvement mechanism is not clear. In this study, the adsorption and nucleation mechanism of molten carbonate on nano-SiC surface were clarified. The DFT calculation results show that the adsorption energy of Li+, Na+ and CO32− is −310, −259 and −654 kJ/mol, respectively, which means the addition of nano-SiC causes a non-uniform distribution of molten carbonate ions around its surface. This affects the subsequent nucleation and results in carbonate segregation. Na2CO3 is the most thermodynamically favorable to adsorb and nucleate, followed by LiNaCO3, and Li2CO3 is the most difficult. The crystalline phase changes of carbonate on nano-SiC surface from solid to liquid phase during melting process were obtained in-situ and the results are consistent with the DFT calculations. Therefore, the adsorption and nucleation mechanism of molten carbonate on nano-SiC surface is well elucidated by the calculations and experiments of this study.

Simulation of freezing process of PCM in existence of nano-sized additives within storage tank

Simulation of freezing process of PCM in existence of nano-sized additives within storage tank

Preparation of a heat storage material from Nano-SiC based composite carbonate with boosted heat storage density for high temperature thermal energy storage

Heat storage materials for high temperature thermal energy storage, e.g., higher than 500 °C, are rather few and their heat storage density (HSD) are insufficient. Therefore, a novel nano-SiC based composite carbonate heat storage material (Nano-SiC CCHSM) was fabricated in this study. The nano-SiC was innovatively applied to improve the HSD of the CCHSM at high temperature. Results show that the addition of nano-SiC significantly improved the HSD of the base material from 542.7 KJ/Kg to as high as 990.7 KJ/Kg. Optimal addition ratio of nano-SiC was 1 % with the sintering temperature of 550 °C. The nano-SiC mainly contributes to improving the sensible HSD of the CCHSM, especially in the liquid sensible HSD. Deep analysis shows that the correlated reaction mechanism is ascribed to the divergent free energy of liquid-phase ions to the nano-SiC, which leads to the heterogeneous nucleation of molten ions and consequently resulting in the high specific heat capacity of the newly formed protruding nanostructures.

APPLICATION OF HYDROGELS FOR CONFORMANCE CONTROL AND FLOW DIVERSION

The use of hydrogels in the development of oil fields by the flooding method has firmly established itself in the oil industry, and this direction is constantly evolving in all oil-producing countries around the world, as evidenced by the growth of publication and patent activity on this topic. Operations for conformance control and flow diversion are impossible to imagine without the use of gel technologies today. Inorganic, organic, and hybrid gels, as well as foam gels, gel-forming and gel-dispersed systems are used.The ability to widely regulate structural-mechanical properties, thermal stability, and shear resistance through the introduction of micro- and nano-sized additives has made hydrogels indispensable tools for petroleum engineers.In this review, modern trends in the use of hydrogels for flow diversion from injection wells are identified, and the most promising directions are explored in light of depleted reservoirs and deterioration in the structure of oil reserves. Geological prerequisites for using hydrogels for flow diversion during field development are discussed, including hydrogels based on a range of acrylamide polymers, sedimentary-gel-forming and gel-dispersed compositions, as well as gels based on inorganic compounds.Various gel-forming compositions based on water-soluble and waterswelling polymers, as well as silicon and aluminum-based inorganic compounds, are used for flow diversion and conformance control. Combining gels with dispersed materials and sedimentary compositions allows for the strengthening of the structural-mechanical properties of the flow-diverting system, making it possible to apply these compositions in fractured-porous collectors. The ability to regulate the gelforming time allows for placement of the gel screen at a specified distance from the injection wellbore. This approach has firmly established itself in industrial practice and continues to be improved in terms of reducing the cost of used compositions and increasing their effectiveness.

Surface Characteristics, Properties and Wear Resistance OF TIB2 BASED Hard-Alloy Coatings Obtained by Electrospark Deposition at Negative Polarity on Ti6Al4V Alloy

In the present work, the possibilities of improving the surface properties of titanium alloy Ti6Al4V by electrospark deposition (ESD) at negative polarity were investigated. The coatings were deposited with a TiB2-TiAl-based hard-alloy electrode with nano-sized additives of NbC and ZrO2. The effect of polarity in ESD at low pulse energy (0.01-0.07 J) on the surface roughness, thickness, composition and structure of coatings was studied by profilometric, metallographic, XRD, SEM and EDS methods. In both polarities, dense and uniform coatings were obtained with roughness and thickness, which could be varied by changing the ESD modes within the range Ra=1.5÷4.5 µm, d= 6÷20 µm and microhardness from 9 to 12 GPa, respectively. It was found that the negative polarity coatings obtained are denser and uniform with higher thickness, lower roughness, finer structure, and lower coefficient of friction, and can be successfully used to reduce the surface roughness and defects of 3D printed titanium alloy. Abrasion and erosion wear tests showed that the wear resistance of coated titanium surfaces at both polarities was 2.2 to 3.5 times higher than that of the substrate. Coatings deposited in positive polarity demonstrated higher resistance to abrasive wear, while those in negative polarity are more resistant to erosive wear.

Geotechnical and engineering properties of expansive clayey soil stabilized with biomass ash and nanomaterials for its application in structural road layers

Clayey soils often pose issues such as swelling, high plasticity, low permeability, and low bearing capacity, particularly in regions with seasonal rainfall. Consequently, soil improvement techniques are necessary for constructing road base layers. Currently, the most used method for road stabilization involves the application of traditional binders such as lime and cement. However, the production of cement and lime has negative environmental impacts and depletes natural resources.In this study, new stabilizing materials based on waste and by-products, as well as a new generation of nanomaterials, are investigated for stabilizing highly plastic and expansive soils. The geotechnical and mechanical properties of soils stabilized with waste materials like biomass ashes from electricity generation, along with small amounts of a silica-based nanotechnological stabilizer, are examined. The obtained results suggest the potential reduction in the use of traditional binders by incorporating by-products, while still maintaining soil properties, and even improving the properties through the application of nano-sized additives.

Monitoring the Rheological Properties of Asphalt Cement after Digestion with Micro and Nano Size Additives

Monitoring the Rheological Properties of Asphalt Cement after Digestion with Micro and Nano Size Additives

Assessing the Influence of Digestion with Micro and Nano Size Additives on the Physical Properties of Asphalt Binder

Assessing the Influence of Digestion with Micro and Nano Size Additives on the Physical Properties of Asphalt Binder

Use of Clay and Titanium Dioxide Nanoparticles in Mortar and Concrete—A State-of-the-Art Analysis

In the past decades, nanomaterials have become one of the focal points in civil engineering research. When added to cement-based construction materials (e.g., concrete), it results in significant improvements in their strength and other important properties. However, the final mix characteristics depend on many variables that must be taken into account. As such, there is no general consensus regarding the influence upon the original material of certain nano-sized additives, the optimum dosage or the synergistic effect of two or more nano-materials. This is also the case for titanium dioxide (TiO2) and nanoclay (NC). The paper focuses on reporting the existing research data on the use of the above-mentioned materials when added to mortar and concrete. The collected data is summarized and presented in terms of strength and durability properties of cement mortar and concrete containing either TiO2 or NC. Both nano-materials have been proven, by various studies, to increase the strength of the composite, at both room and elevated temperature, when added by themselves in 0.5%~12% for TiO2 and 0.25%~6% for NC. It can be inferred that a combination of the two with the cementitious matrix can be beneficial and may lead to obtaining a new material with improved strength, elastic and durability properties that can be applied in the construction industry, with implications at the economic, social and environmental levels.

Detecting the Impact of Micro and Nano Size Additives on Deformation of Asphalt Concrete

Permanent deformation is considered as one of the major distress type of asphalt concrete pavement in the hot climate region. It can be controlled by the use of additives either for asphalt binder or for the asphalt concrete mixture. In the present assessment, the impact of micro and Nano size additives (fly ash and silica fumes) on the deformation behaviour of asphalt concrete mixtures was assessed. Such additives were implemented as partial substitute of mineral filler. Asphalt concrete slab samples were prepared in the laboratory with the aid of roller compaction. The optimum percentages of the additives are (2 and 4) % of silica fumes and coal fly ash respectively by the weight of the binder. Beam specimens were obtained from the slab samples and tested for fatigue life under three constant strain levels using four point bending beam technique. It was observed that for mixture treated with Nano additive (silica fumes), the reduction in the permanent deformation starts at 0.0001 MJ/m3 loss in energy for 750 microstrain level. However, for mixture treated with Micro size additive (fly ash), as the dissipated energy vanishes, the permanent deformation was in the range of (3 - 4.5) microstrain. It was concluded that as the dissipated energy vanishes, the permanent deformation was lower by (29.4 and 11.7) % for mixtures treated with silica fumes and fly ash additives respectively as compared with the control mixture.

Effect of nano-SiC doping on the structure and superconducting properties of Mg(B1-xCx)2.

Carbon doping is studied in MgB2 pellets during one-step synthesis by solid-state reaction, employing both undoped and carbon-doped boron with and without the addition of nano-SiC. The phase formation during the synthesis as a function of time was followed using powder X-ray diffraction and Rietveld refinement. The superconducting properties were characterized with a magnetometer to investigate doping-induced changes. Mg(B1-xCx)2 is obtained with nano-precipitates and different compositions depending on the synthesis temperature. It is found that the addition of nano-SiC prevents the phase formation at low temperature (700°C). Nevertheless, the best superconducting properties are obtained for the sample treated at 900°C using simultaneously C and SiC, with a critical current density of 105 A cm-2 at 3 T and 20 K, named the 900-20-C-nanoSiC sample.

Assessing the Impact of Micro and Nano Size Additives on the Dissipated Energy of Asphalt Concrete Through Fatigue

Assessing the Impact of Micro and Nano Size Additives on the Dissipated Energy of Asphalt Concrete Through Fatigue

Obtaining fine-grained hard alloys homogeneous in carbide grain

The actual task of this work is to obtain homogeneous hard alloys with fine carbide grains, combining high hardness and strength. Studies were carried out to establish the most favorable phase compositions of hard alloys and the most rational technical methodology for their production. In this research work, a nanostructured WC-TiC-Co powder charge was obtained by mechanochemical synthesis. Nanosized WC powder and nanopowder with precipitated Co were added to the hard alloy charge by mixing in a ball planetary mill. The process of pressing the powder charge at a pressure of 100-1000 MPa, as well as the sintering process at a temperature within the range of 1450-1600℃ was applied. The chemical-metallurgical method of deposition of metal layers from salt solutions was applied to obtain the WC-Co hard alloy. X-ray structural analysis and scanning electron microscopy were applied. The effect of the preparation method on the phase composition of WC-TiC-Co consolidated samples was studied. In the microstructure of these hard alloys, intercrystalline particles of (Ti,W)C are observed, and the presence of the liquid phase can lead to a rounded shape. It was found that the addition of nano-sized WC powder leads to an increase in pressed density. It was revealed that the addition of WC nanosize additives or WC nanopowder with deposited cobalt makes it possible to obtain a fine-grained structure with a grain size of not more than 4-6 microns. It was found that the addition of WC nanopowder with precipitated cobalt to the alloy has the highest Brinell hardness values; in addition, it leads to an increase in the bending strength.

Improvements in the Engineering Properties of Cementitious Composites Using Nano-Sized Cement and Nano-Sized Additives.

The findings of an extensive experimental research study on the usage of nano-sized cement powder and other additives combined to form cement-fine-aggregate matrices are discussed in this work. In the laboratory, dry and wet methods were used to create nano-sized cements. The influence of these nano-sized cements, nano-silica fumes, and nano-fly ash in different proportions was studied to the evaluate the engineering properties of the cement-fine-aggregate matrices concerning normal-sized, commercially available cement. The composites produced with modified cement-fine-aggregate matrices were subjected to microscopic-scale analyses using a petrographic microscope, a Scanning Electron Microscope (SEM), and a Transmission Electron Microscope (TEM). These studies unravelled the placement and behaviour of additives in controlling the engineering properties of the mix. The test results indicated that nano-cement and nano-sized particles improved the engineering properties of the hardened cement matrix. The wet-ground nano-cement showed the best result, 40 MPa 28th-day compressive strength, without mixing any additive compared with ordinary and dry-ground cements. The mix containing 50:50 normal and wet-ground cement exhibited 37.20 MPa 28th-day compressive strength. All other mixes with nano-sized dry cement, silica fume, and fly ash with different permutations and combinations gave better results than the normal-cement-fine-aggregate mix. The petrographic studies and the Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) analyses further validated the above findings. Statistical analyses and techniques such as correlation and stepwise multiple regression analysis were conducted to compose a predictive equation to calculate the 28th-day compressive strength. In addition to these methods, a repeated measures Analysis of Variance (ANOVA) was also implemented to analyse the statistically significant differences among three differently timed strength readings.

Tribological Behavior of 3D-Printed Nanometer SiC and SiO2 Particle-Reinforced Polyamide 12 Composites by Selective Laser Sintering under Seawater Lubrication Condition.

Polymeric matrix composites have been widely used in the marine field. In this study, the tribological behavior under seawater-lubricated conditions of pure Polyamide 12 (PA12), micron-SiC and nanometer SiC and SiO2 particle-reinforced PA12 composites, which are prepared by selective laser sintering (SLS), were studied. The seawater absorption, hardness, contact angle and tribology performance were investigated. The results show that the addition of micron- and nano-SiC particles and nano-SiO2 particles could decrease the seawater adsorption and contact angle, and increase the hardness. Under seawater conditions, the addition of micro SiC particles can reduce the friction coefficient and wear loss, whereas the addition of nano-SiC and -SiO2 particles increases the corresponding values. The specimen printed with recycled powder has a higher friction coefficient, while having a better wear resistance. However, it increases the width and depth of the wear track in some locations. The wear mechanisms of the composite specimens are also analyzed. This was the result of the combined effects of fatigue wear and abrasive wear under seawater conditions. The latter plays a dominant role under seawater conditions. This study may provide a valuable reference for the further research and application of polymeric matrix composites in marine engineering equipment.

Thermal storage evaluation in existence of nano-sized additives by mean of numerical method

To achieve greater productivity of discharging process is storage system, the geometry of container and features of working material have been improved in current work with installing fins and loading nanoparticles, respectively. Three radiuses for alumina nanoparticles with two amounts of concentration have been selected for managing various cases of simulations. The features of NEPCM were estimated with considering single phase approximation and mathematic model was derived with considering theory of overlooking velocity of NEPCM. The grid style was altered for each time periods according to position of solid layer. The good accuracy of utilized code has been reported in validation section. The freezing time changes from 2013.32 s to 1273.41 s with adding nanoparticles with optimized diameter and concentration of 0.04. As radius changes from 15 nm to 20 and 25 nm, the needed time at first declines around 17.07 % and then it increases around 16.43 %. The efficacy of ϕ for radius of 20 nm is much greater other sizes.

Assessment of energy storage container with involve of nano-sized additives

For accelerating the discharging process, the thermal feature of PCM has been enhanced in this study with inclusion of nano-powders. Besides, utilizing curved shaped container can increase the speed of ice front reaching to inner zones. Negligible efficacy of velocity of liquid PCM makes the poor impact of convection in this phenomena and coupling of temperature equations and SF creates the mathematical model. Turning to accurate solution, the immediate step is utilizing adaptive grid which is combined with finite element approach. Good agreement was reported for validation test. The required NEPCM properties have been measured according to single phase formulation involving the impact of diameter of particle in calculation of conductivity. Adding alumina nanoparticles can decrease the need time about 8.29 % to 41.2 % for present modeling. Besides, utilizing optimum size of powder instead of dp = 30 nm makes the freezing time to reduce about 19.96 %.