Nano-sized Additives Research Articles

Effect of nano-sized metallic Au additions at large scale on the phase stability of Bi-2212 ceramics

Bi1.8Sr2AuxCa1.1Cu2.1Oy (Bi-2212) polycrystalline ceramics with x = 0.25, 0.3 and 0.35 have been prepared by the solid-state reaction method. XRD results showed the Bi-2212 phase as the major one in all samples, accompanied by metallic Au, and some secondary phases such as Bi2CaO4. Tc values are very similar for all samples, indicating that the carrier concentration is independent of the amount of Au. Magnetic properties of samples, determined through magnetic hysteresis measurements (M–H) performed at both T = 2 and 10 K, showed that samples maintain their diamagnetic characteristics in all cases. In addition, Jc values, calculated from their magnetic hysteresis loops using the Bean’s model, showed that addition of metallic Au in high contents leads to an important increase when compared to the samples with low Au content.

Effect of SBS molecular structure on the rheological properties of ternary nanomodified bituminous binders

The work presented in this paper focused on the rheological properties of ternary composites for paving applications constituted by bitumen, nano-sized additives and polymer modifiers. Non-functionalized multiwall carbon nanotubes and two types of styrene-butadienestyrene polymers, linear and radial, were used to modify a reference neat bitumen with the specific goal of highlighting the effects of polymer structure on the final properties of composites. Binary blends containing a single additive were also investigated for comparative purposes. Materials were characterized by means of dynamic mechanical analysis and their internal structure was assessed with fluorescence microscopy observations. Experimental outcomes indicated that polymer architecture played a crucial role in promoting effective interactions between modifiers and carbon nanotubes. Specifically, in the presence of linear styrene-butadienestyrene, carbon nanotubes acted as compatibility activators, leading to the formation of stable and continuous ternary systems. On the contrary, in the case of radial styrene-butadienestyrene, beneficial effects provided by nano-modification were jeopardized by the increased thermodynamic instability which resulted from the combined use of these two components.

ЕФЕКТИВНІСТЬ НАНОДИСПЕРСОВИХ РЕЧОВИН ВИКОРИСТАННЯ В МЕХАНІЗМАХ КОРАБЛЯ

The history of civilization is inseparably associated with the development of high-quality materials technology [1]. Modern materials science, aimed at the production of the materials with special properties, is connected with the fundamental and applied science of nanotechnology which studies the laws of physical and chemical nano-sized systems. Almost all nanosystems are obtained under the conditions far from equilibrium. It allows achieving spontaneous nucleation, and to avoid growth and aggregation of the formed nanoparticles. Studies have shown that nano-based materials have new and sometimes unusual properties [2]. It is known that for conventional materials the greater the strength of the material the less its ductility. In nanomaterials, a new paradox [3] of strength and ductility (a simultaneous increase in strength and ductility) has been discovered. In addition, nanomaterials have a higher fracture toughness and substantial wear resistance. The physical nature of the new phenomenon is connected with the change of micromechanisms of deformation, when, along with the motion of lattice dislocations at the boundary of formed nanograins, grain-boundary glide occurs [4]. Additives to operating media are widely used in mechanism’s systems. In particular, the reliability of friction units is determined in many respect with the presence of antiwear and boundary additives in lube oils. The transition from micron- to nano-sized additives is being widely implemented in technology at present. In this paper, we have analyzed the effectiveness of the utilization of nanodispersed substances and their compounds in order to increase the service life of the ship’s equipment.

Correlation between damage evolution and resistivity reaction of concrete in-filled with graphene nanoplatelets

Pilot researches prove that graphene nanoplatelets (GNPs) are promising nano-sized additives to improve the smartness of cementitious materials. This work aims to reveal the explicit correlation between the damage development and the resistivity reaction of cementitious composites infilled with GNPs. A weight content of 4.5% (GNPs/cement) is used to cast two groups of concrete samples, named as C20 and C30 (according to their designed compressive strength), whose volume fractions of GNPs are 0.43% and 0.61%, respectively. Investigations shows different failure patterns during compression loading and their piezoresistive characteristics are probed systematically. Additionally, damages determined by strain-stress curves and ultrasonic pulse velocity penetrations in the middle section are also studied for comparing. The damage evolution process illustrated by resistivity reactions contains a slight decrease of resistivity within the elastic regime, a moderate damage developing stage before the peak force, an expeditive damage section just after the peak force and a relaxed damage expanding when the stress drops to less than 50% of the strength. At last, the damages obtained with resistivities increase to 0.8. This indicates that the piezoresistivity of smart concrete containing GNPs can be a promising tool to detect damages detailedly.

Effect of nano-sized sintering additives on microstructure and mechanical properties of Si3N4 ceramics

Nano-sized sintering additives such as MgO, Al2O3, Y2O3 and La2O3 are added to process Si3N4 based ceramics. The effects of such sintering additives on the phase transformation, mechanical properties and microstructure of silicon nitride were investigated. XRD analysis of sintered silicon nitride with these sintering additives have shown the complete transformation of α-Si3N4 into β-Si3N4. The silicon nitride ceramics sintered with nano-sized additives (4MgO-4Al2O3–5La2O3) have exhibited the highest fracture toughness. This is not only due to the weak glass|grain interface but also due to the formation of high aspect ratio grains (β-Si3N4). Superior mechanical properties of Si3N4 can be obtained by way of adding small and large RE3+ radii RE2O3 (Y2O3 and La2O3) together than the addition of single RE2O3.

Improvement of efficiency of use of liquid-glass mixtures Part 3. Nanodispersed materials

The mechanisms of interaction of various ultradisperse substances with molding materials, as well as their influence on physical and technological properties, are considered. Examples of using of ultrafine nano-sized additives in foundry are given. The possibilities of increasing level of technological properties (initial strength, gas permeability and non-stick properties) of mixtures due to additives of UPC, which contributes the improvement of the surface quality of castings and to the reduction laboriousness of finishing operations are described.

The Effect of Laser Power on the Interface Microstructure of a Laser Remelting Nano-SiC Modified Fe-Based Ni/WC Composite Coating

The plasma sprayed Fe-based Ni/WC composite coating on the surface of 45 steel was post-treated by laser remelting with the addition of nano-SiC. The effect of laser power on the interface microstructure of a laser remelting nano-SiC modified Fe-based Ni/WC composite coatings were researched. The metallographic structure, microscopic morphology, phase composition, and microhardness of the remelted layer were visually analyzed by metallographic microscope, scanning electron microscope (SEM), X-ray diffractometer (XRD), and microhardness tester, respectively. The results showed that the nano-SiC modified remelted coating was smooth and compact, and with no fine cracks. The remelted layer was mainly composed of [Fe,Ni], Cr, Fe0.04Ni0.36 phase. The metal elements Fe, Ni, Cr, and Si, and non-metallic element C, appeared to diffuse, and there was metallurgical bonding between the coating and the matrix. With the increase of laser power, the smaller the average grain size, the wider the half-peak height (FWHM), and the more obvious the grain refinement. When the laser power was 500 W, the interface metallurgical showed the best effect. Furthermore, the nano-sized SiC particles served as the core of the heterogeneous nucleation to refine the grains on the one hand, and promoted the formation of a hard intermediate phase in the coating on the other hand. Therefore, the laser remelting and the addition of nano-SiC particles greatly improved the microhardness of the coating. The larger the laser power, the smaller the microstructure characteristics and the fewer the number of holes. With increasing laser power, the hardness increased in general terms and the maximum hardness increased by 51%.

A novel strategy of smart manipulation by micro-scale oscillatory networks of the reactionary zones for enhanced extreme thrust control of the next-generation solid propulsion systems

Abstract The main aim of this research is to get a better knowledge and understanding of the micro-scale oscillatory networks behavior in the solid propellants reactionary zones. Fundamental understanding of the micro- and nano-scale combustion mechanisms is essential to the development and further improvement of the next-generation technologies for extreme control of the solid propellant thrust. Both experiments and theory confirm that the micro- and nano-scale oscillatory networks excitation in the solid propellants reactionary zones is a rather universal phenomenon. In accordance with our concept, the micro- and nano-scale structures form both the fractal and self-organized wave patterns in the solid propellants reactionary zones. Control by the shape, the sizes and spacial orientation of the wave patterns allows manipulate by the energy exchange and release in the reactionary zones. A novel strategy for enhanced extreme thrust control in solid propulsion systems are based on manipulation by self-organization of the micro- and nano-scale oscillatory networks and self-organized patterns formation in the reactionary zones with use of the system of acoustic waves and electro-magnetic fields, generated by special kind of ring-shaped electric discharges along with resonance laser radiation. Application of special kind of the ring-shaped electric discharges demands the minimum expenses of energy and opens prospects for almost inertia-free control by combustion processes. Nano-sized additives will enhance self-organizing and self-synchronization of the micro- and nano-scale oscillatory networks on the nanometer scale. Suggested novel strategy opens the door for completely new ways for enhanced extreme thrust control of the solid propulsion systems.

Numerical study on the effect of operating nanofluids of photovoltaic thermal system (PV/T) on the convective heat transfer

Photovoltaic (PV) collectors are replaced with hybrid photovoltaic thermal (PV/T) systems to establish an electrical and thermal yields. The main function of such design is to provide cooling for the solar cell by absorbing its temperature. This temperature is used for the thermal energy generation of this hybrid design. High electrical and thermal efficiencies are associated with PV/T's. In this study, mathematical analysis was used to examine the effect of the type of nanoparticles added (SiC, CuO, and Al2O3), and the type of base fluids (water, glycerin, and ethylene glycol) on the convection heat transfer of PV/T system. The solar simulator type 'MINI-EESTC' was modified to work as a PV/T was used in the practical part of the study.The numerical results showed the base fluid and the added nanoparticles' thermophysical properties effect on the convective heat transfer and pressure drop. Glycerin showed the maximum pressure drop while water indicated the minimal value. The addition of nano-SiC for the studied base-fluids afforded higher convective heat transfer than nano-CuO and nano-alumina. The validation of the numerical results with the practical one showed a good agreement.

The effects of nanosilica on charpy impact behavior of glass/epoxy fiber reinforced composite laminates

Desire to improve the efficiency of composite materials for engineering applications has led to the use of nano-sized additives or fillers such as nanoclay, nanosilica, nano-graphene, carbon nanotubes. The effect of nanoparticle inclusion on mechanical properties of fiber reinforced composite materials has been investigated by many researchers and crucial effects have been reported in several papers. In this work, the effects of nanosilica content on the low velocity impact behaviors of glass/epoxy fiber reinforced composite laminates are determined using Charpy impact tests. The composite laminates are fabricated via hand lay-up followed by hot press molding. The nanosilica particles with different weight percentages are dispersed in epoxy resins using mechanical stirring. The absorbed impact energy values of flatwise-unnotched and edgewise-notched beam specimens, and impact damages are analyzed as a measure of impact behavior. The results show that the incorporation of nanosilica particles have significant effects on the Charpy impact behavior.

Study on the Influence of Nano-SiC on the Structure and Properties of Nodular Cast Iron

In this paper, the effect of adding Nano-SiC on the structure and mechanical properties of nodular cast iron during inoculation and spheroidizing process is mainly studied. Three sets of samples were set up: one group is without adding Nano-SiC, and the other two groups are adding Nano-SiC in the spheroidizing process and inoculation step. The three groups of castings were sampled from the core and 1/4 respectively and treated by isothermal quenching. The influences of Nano-SiC and heat treatment process on the microstructure and mechanical properties of nodular cast iron were discussed through the observation of impact work, hardness and metallographic structure of Vivtorinox. The experimental results show that with the addition of Nano-SiC, the spheroidization rate, spheroidization degree and graphitization of the graphite in casting structure are improved. In mechanical properties, the impact toughness of the samples with adding Nano-SiC during inoculation is the best, and the hardness of nodular cast iron can be improved. After heat treatment, the impact toughness of nodular cast iron samples increased obviously, but the hardness decreased generally.

Impact compaction of ultra high molecular weight polyethylene

Ultra high molecular weight polyethylene (UHMWPE) is a partially crystalline polymer with unique physical and mechanical characteristics. Therefore it finds a wide use in present-day mechanical engineering. Experiments on impact compaction of UHMWPE granules were performed on the special facility designed for consolidation of powders. Bulk samples were made out of GUR 4150 powder with molecular weight of 9.2·106 g/mol. The method of impact compaction permits to make not only pure UHMWPE compacts, but material with micro- and nano-sized additions as well, and produce composites with reinforcing metal structures.

The Effect of Mechanical Milling on Graphite–Boron Carbide Hybrid Reinforced ZA27 Nanocomposites

The main focus of this study is concentrated on the effect of mechanical milling on graphite–boron carbide hybrid reinforced ZA27 nanocomposites. With this respect, nano-sized graphite (Gr) and boron carbide ( $$\hbox {B}_{4}$$ C) reinforced ZA27 matrix nanocomposites were fabricated via a combination of mechanical milling (MM) and hot pressing techniques. MM method was used to produce a ZA27-based hybrid nanocomposite (ZHNC) that nano-sized additives dispersed homogenously in ZA27 matrix. Microstructural and mechanical properties of the nanocomposites were scrutinized as a function of milling time using X-ray diffractometer, scanning electron microscope, hardness and tensile testing machines. Results show that MM method can be utilized for homogeneously distributing the nano-sized additives. Flake-shape morphology negatively influences physical and mechanical properties. It was also found that grain and particle size is decreased after 12 h milling process. With increasing MM time, homogeneous microstructure of the nanocomposite bulk materials was obtained and subsequently their mechanical properties were improved considerably.

Enhanced photo-fermentative hydrogen production of Rhodopseudomonas sp. nov. strain A7 by the addition of TiO2, ZnO and SiC nanoparticles

In order to strengthen photo-fermentative hydrogen production by different photocatalytic nanoparticles, hydrogen production by photo-fermentative bacteria with addition of TiO2, ZnO and SiC nanoparticles in batch culture were investigated in this study. The results indicated that three nanoparticles could improve hydrogen production performance of Rhodopseudomonas sp. nov. strain A7 under respective optimal conditions. The hydrogen yield of 2.81 mol-H2/mol-acetate was obtained when TiO2 nanoparticles with a concentration of 300 mg/L and size of 25 nm. The concentration of ZnO nanoparticles was at 100 mg/L, hydrogen yield reached 2.64 mol-H2/mol-acetate. Compared with TiO2 and ZnO nanoparticles, SiC nanoparticles exhibited greatest potential for enhancing photo-hydrogen production. By addition of nano-SiC with concentration of 200 mg/L which was prepared at temperature of 1500 °C, the maximum hydrogen volume, average hydrogen content and hydrogen yield of strain A7 were achieved at 2272 mL-H2/L-culture, 85.2% and 2.99 mol-H2/mol-acetate, respectively. And hydrogen production was 18.6% higher than that of alone strain A7 without the addition of nanoparticles. Therefore, the addition of SiC nanoparticles is a promising strategy to improve photo-fermentative hydrogen production from wastewater.

The Effect of Particle Size Distribution and the Nano-Sized Additives on the Quality of Annulus Isolation in Well Cementing

The Effect of Particle Size Distribution and the Nano-Sized Additives on the Quality of Annulus Isolation in Well Cementing

Vpliv dodatka nanodelcev kobaltovega oksida na zgradbo in električne lastnosti NTC termistorjev na osnovi nikljevega manganita

Vpliv dodatka nanodelcev kobaltovega oksida na zgradbo in električne lastnosti NTC termistorjev na osnovi nikljevega manganita

Experimental investigation on mechanical and piezoresistive properties of cementitious materials containing graphene and graphene oxide nanoplatelets

Recent investigations show that graphene nanoplatelets (GNPs) and graphene oxide nanoplatelets (GONPs) are promising nano-sized additives to enhance the mechanical property and smartness of cementitious materials. To further delineate the collective effects of GNPs and GONPs, particularly their contents, on the performance of concrete, a comprehensive investigation is carried out in this study. Mortar samples, characterized by different water-cement ratios and containing different amounts of GNPs and GONPs, are experimentally tested to systematically probe their strength, electrical resistance and piezoresistive reactions. The results show that to take advantage of GNPs and GONPs, the water-cement ratio and associated workability of concrete are important. With a proper water-cement ratio, a small percentage of GNPs and GONPs can significantly improve the concrete strength, while the content of GNPs needs to be substantially increased to achieve low electrical resistance and accurate piezoresistive reaction. To understand the mechanisms of conductivity and piezoresistance at the micro-scale, micro-characterization utilizing Scanning Electrical Microscopy (SEM) equipped with Energy Dispersive Spectrometer (EDS) technique is performed to examine the mortar microstructure containing GNPs. In addition, rapid chloride corrosion test on the selected mortar samples shows that the migration of chloride ions slows down with the addition of GNPs in cement paste.

Evaluation of boron nitride particles on the tribological performance of avocado and canola oil for energy conservation and sustainability

In the present investigation, experiments were conducted using a pin-on-disk apparatus to study the tribological performance of environmentally friendly multi-phase lubricants consisting of natural plant-based liquid lubricants and hexagonal boron nitride (hBN) solid additives. Among the natural plant-based liquid lubricants, a high oleic acid lubricant, such as avocado oil, showed the best tribological performance when compared to other natural plant-based lubricants, which further demonstrated the importance of appropriate natural oil selection for tribological applications. In order to develop an optimal multi-phase lubricant, hBN particles with varying sizes were incorporated as additives in the avocado oil. Experiments revealed that particle additive size with regards to initial surface roughness affects the tribological performance of the multi-phase lubricant. It was found that this multi-phase lubricant with nano-sized additives showed the best performance when compared to multi-phase lubricants with micron-sized and submicron-sized additives. More specifically, the lubricant mixtures had friction reductions from 8 to 64 % for particles ranging from micron-sized to nano-sized, respectively. The wear also decreased in the lubricant mixtures with reductions from 13 to 70 % for particles ranging from micron-sized to nano-sized, respectively. These mechanisms for enhanced tribological performance are discussed in this investigation.

The Effect of the Addition of Nano-SiC and Nano-TiN in the ZGMn13Cr2 Alloy on the Microstructure and Mechanical Properties

The modifiers of nano-SiC and nano-TiN were added into the melt of ZGMn13Cr2 alloy, respectively. The effect of the additions on the microstructure and mechanical properties were investigated. Results show that the two kinds of nano modifiers both have refining effect and make the improvement of impact toughness and wear resistance.

Fatigue and healing properties of bituminous mastics reinforced with nano-sized additives

The research work described in the paper focused on fatigue and healing properties of bituminous mastics reinforced with nano-sized additives. Commercially available multiwall carbon nanotubes (CNTs) and montmorillonite nanoclay (NC) were combined with a single base bitumen and a standard mineral filler to produce bituminous mastics. These blends were prepared in the laboratory by making use of a technique consisting in simple shear mixing followed by sonication. Fatigue behaviour of mastics under repeated loading was investigated by means of time sweeps performed in the strain-controlled mode at various amplitudes. Healing potential was assessed by adopting a testing protocol specifically conceived to discriminate between recovery of damage induced by fatigue loading and other artefact phenomena which may affect material response. All rheological measurements were carried out with a dynamic shear rheometer in the parallel plates geometry. Outcomes of the experimental investigation were found to be highly dependent on the nature of additive type, as a result of the key role played by interaction mechanisms that nano-particles can establish within the bituminous mastic.