Effect Of Particle Addition Research Articles

The flexoelectric properties of various polymers and energetic composites

Electroactivity of polymers used in energetic materials may result in charge separation that could result in safety concerns (unintentional ignition) or be exploited for multifunctional applications. We measured the flexoelectric properties of several polymers and energetic composites including poly(vinylidene fluoride-co-trifluoroethylene) [P(VDF-TrFE)], nanosized aluminum (nAl)/P(VDF-TrFE), poly(vinylidene fluoride-co-hexafluoropropylene) [P(VDF-HFP)], micron aluminum (μAl)/P(VDF-HFP), hydroxyl-terminated polybutadiene (HTPB), ammonium perchlorate (AP)/HTPB, μAl/AP/HTPB, polytetrafluoroethylene (PTFE), and polydimethylsiloxane (PDMS). The presence of flexoelectricity in PTFE (Teflon®) and the relatively high flexoelectric coefficient of P(VDF-HFP) (Viton®) measured in this work may help explain accidents involving the production and use of Magnesium-Teflon-Viton (MTV) that in many instances have been attributed to electro-static discharge. The addition of aluminum nanopowders to the P(VDF-TrFE) increased the flexoelectric coefficient by ∼30%. However, the addition of aluminum micrometer particles (10 wt. %) to P(VDF-HFP) decreased the effective flexoelectric coefficient, while an increase was observed when the aluminum loading was increased from 10 to 20 wt. %. The effective flexoelectric coefficient of HTPB and two propellant compositions (AP/HTPB and μAl/AP/HTPB) were measured to be in the same range as each other. The effect of particle addition (nAl, μAl, and AP) on flexoelectricity was different depending on the binder, further illustrating the complexity of flexoelectric properties in composite energetics. This may be somewhat explained by competing effects where particle additions (nAl, μAl, and AP) create additional strain gradients that contribute to flexoelectricity, but the particle additions also replace the mass of flexoelectric polymer binders (P(VDF-TrFE, P(VDF-HFP), and HTPB) with particles (nAl, μAl, and AP) that are less flexoelectric.

The role of ceramic particle loading and the influence of hot extrusion on the tribological behaviour of aluminium alloy-SiCp composites

Aluminium matrix composites (AMC) are gaining wide popularity in various sectors due to their excellent properties which are synergic. Apart from strength, wear resistance of a material is also an essential criterion for the number of applications. Extensive studies are being carried out on the secondary processing of these materials to enhance the suitability of the AMC for engineering applications. In this study, initially, Al 2014 base alloy and their composites with 5, 10, and 15 wt.% SiCp fabricated by stir casting route were subjected to wear test. Based on the encouraging wear performance, the Al-10 wt.% SiC composite was further subjected to extrusion. Pin-on-disc sliding wear tests on the as-cast & extruded base alloy and the composite samples were carried out at a constant load of 20 N for a total sliding distance of 1000 m with a velocity of 2 m/s. Microhardness and porosity measurements were carried out besides the study of wear performance, such as coefficient of friction and wear by weight loss. The worn surfaces were analyzed both by optical and scanning electron microscopes. The effect of particle addition, extrusion, porosity, and microhardness on the wear performance of the samples was discussed. Among the samples studied, the Al-10 wt.% SiC composite extruded at a ratio of 8:1 is found to have the highest wear resistance.

The effects of nano- and micro-particles on properties of plasma electrolytic oxidation (PEO) coatings applied on titanium substrates: A review

Plasma electrolytic oxidation (PEO) technique has been rapidly developed as a method of producing biocompatible, hard, corrosion-resistant, and wear-resistant as well as having good adhesion coatings in recent years. Due to the PEO coatings remarkable properties, they are used in order to modify the surface and improve properties of light metals such as aluminum, magnesium, titanium, etc. Since several parameters impact the microstructure and phase composition and subsequently the properties of PEO coatings, it is important to investigate the effects of these parameters and optimize them. One of these parameters that plays a major role in changing the properties of PEO coatings is the chemical composition of the electrolyte which can be altered by changing the components and/or their concentrations and adding different nano- and micro-particles. Due to the good performance of nano- and micro-particles in improving the corrosion behavior of PEO coatings, this review focuses on effects of particles addition into the electrolytes on corrosion behavior of PEO coatings on titanium in addition to its alloys. Also, in this review, the mechanism of embedding particles to PEO coatings and the effects of particles addition on phase composition, microstructure, roughness, adhesion, and thickness of coatings are discussed.

Shear rheological properties of composite fluids and stability of particle suspensions: Potential implications for fracturing and environmental fluids

Composite fluids are comprised of particles and polymers and are used for fracking and the in‐situ treatment of subsurface contaminants. This study investigates the correlation between the shear viscoelasticity of guar aqueous solutions and their effectiveness in suspending sand, which is a common fracking proppant. In the absence of a crosslinker, the shear viscous modulus (G”) of 5 g/L guar solutions was greater than the shear elastic modulus (G’). When the crosslinker borax was added, the guar solutions behaved as yield stress fluids (G’ > G”). Sand was well‐suspended in the crosslinked guar solutions but settled in non‐crosslinked fluids. Similar results were obtained with fenugreek gum. This study also investigates the correlation between particle settling and the effect of particle addition on the rheology of the fluids. Granulated activated carbon (GAC) particles are utilized to remediate polluted sites and were used as model particles. Guar and xanthan effectively suspended the GAC. Anionic polyacrylamide effectively suspended the GAC but not after soaking in sodium dodecyl sulphate. Zetag 8167 did not effectively suspend the GAC. The addition of 10 g/L of GAC did not affect the shear rheology of the fluids that suspended them, but decreased the shear viscoelastic moduli of the polymeric fluids that could not suspend them.

Effect of particle addition on boiling heat transfer performance of saw-tooth surface

Effect of particle addition on boiling heat transfer performance of saw-tooth surface

The Effect of Particles on Surface Tension and Flotation Froth Stability

It is widely accepted that particles stabilise flotation froths and that stable froths result in improved flotation performance. Predicting the effect of particle addition on froth stability is, however, challenging. Dynamic surface tension measurement using maximum bubble pressure presents an attractive technique to investigate the effect of surfactant and particles at the air-water interface. The range of bubble lifetimes that can be studied (typically 0.1 to 60 s) is analogous to variations in air rate in flotation cells, and the corresponding changes in surface tension give an indication to the diffusion and adsorption rates of particles at the interface. In this paper, we use dynamic surface tension measurements to investigate the effect of particles on bubble surfaces at the microscale and link this to bulk froth stability measurements carried out using a froth column. Using the maximum bubble pressure method, the results show that the addition of particles results in lower surface tension, both at the dynamic (i.e. short) bubble lifetimes and towards equilibrium (i.e. 60 s bubble lifetime). This corresponds with the bulk froth stability measurements, where the three-phase system yielded more stable froths than the surfactant only system. Furthermore, increased particle loading at the air-water interface, whether through higher surfactant concentrations or lower air rates (longer bubble lifetimes), gave lower surface tension and higher froth stability. This demonstrates the link between bubble loading and froth stability. It is proposed that the maximum bubble pressure technique can be used to predict froth stability for two- and three-phase systems, enabling the effect of particle loading to be accounted for and quantified. Moreover, the technique has the potential to allow rapid determination of particle and surfactant diffusion at the air-water interface and prediction of the corresponding effect on bulk froth behaviour.

No.3 粉体添加による装入炭充填密度向上効果

No.3 粉体添加による装入炭充填密度向上効果

Food-grade Pickering stabilisation of foams by in situ hydrophobisation of calcium carbonate particles

The aim of this study was to investigate the possibility of stabilising foam bubbles in water by adsorption of calcium carbonate (CaCO3) particles. Because CaCO3 is hydrophilic and not surface-active, particles were hydrophobised in situ with several emulsifiers. The used emulsifiers were food-grade and negatively charged at the pH employed. The effect of particle addition on foamability and foam stability of solutions containing either β-lactoglobulin, sodium caseinate, Quillaja, sodium dodecanoate (SD) or sodium stearoyl-2-lactylate (SSL) was studied. It was found that the ability of the emulsifiers to induce surface activity such that the particles are able to adsorb to the air-water interface is related to their structure. The structure needs to consist of a well-defined hydrophobic part and a charged part. Large emulsifiers with a complex structure, such as β-lactoglobulin, sodium caseinate and Quillaja, were able to partially hydrophobise the particles but were not able to act synergistically with the particles to increase the foam stability. Low molecular weight emulsifiers, however, consisting of a single tail with one charged group, such as SD and SSL, adsorbed at the particle surface rendering the particles partially hydrophobic such that they adsorb to the air-water interface. In a subsequent investigation, the pH was changed to a value typical for food products (pH 6–7) and the addition of milk salts on the foamability and foam stability was assessed. Based on these results, the use of food-grade CaCO3 particles hydrophobised in situ with food-grade surfactants (SD or SSL) to prepare ultra-stable aqueous foams is demonstrated.

Mechanical and fracture behavior of B4C reinforced Al composites produced by hot pressing

Abstract In this study, the effects of particle addition on the microstructure, mechanical properties and fracture behaviors of Al/B4C particle reinforced composite produced by hot pressing method were investigated. After the production of 5, 10 and 15 wt.-% of B4C reinforced composites, T6 heat treatment was applied. It was specified that a strong interface bond occurred between the matrix and particles, and during the fracturing of composites, this effect increased the particle fracture. It was observed that particles were fractured parallel to the fracture surface and to each other fracture surface of MMCp. In general, cavity of particle separated from the matrix was not seen. In the production of MMCp, it was also observed that hot pressing provided a density higher than 99 %. After the heat treatment the maximum hardness value of 173 HB was reached with 15 wt.-% B4C reinforced sample. The transverse rupture strength (TRS) decreased with the increase of reinforcement ratio. The highest TRS was 510 MPa with the 5 wt.-% reinforced material, whereas the lowest value was obtained to be 387 MPa with the 15 wt.-% B4C reinforced material.

Effect of Particle Addition on Ultrasonic Degradation Reaction Rate

The ultrasonic degradation of methylene blue at a frequency of 490 kHz was carried out in the absence and presence of TiO2 or Al2O3 particle, and the effects of amounts of particle on the enhancement of degradation rate constant estimated by assuming first-order-kinetics were investigated. The degradation reaction was enhanced by particle addition, and the apparent degradation rate constant is proportional to the increase in amount of particle. In addition, the constant of proportionality is not influenced by degraded material and ultrasonic frequency. However, particle type influences the constant of proportionality, and the value of TiO2 particle is about 6 times as large as that of Al2O3 particle.

Effect of Addition of Energetic Nanoparticles on Droplet-Burning Rate of Liquid Fuels

A droplet stream combustion experiment was developed to understand the effect of reducing droplet size to a micrometer scale on the combustion characteristics of nanofluid fuels, which are liquid fuels with a stable suspension of nanoparticles. Pure ethanol and ethanol with aluminum nanoparticles at varying concentrations (up to 5 wt%) and droplet sizes were studied. The effect of particle addition on the droplet-burning rate was determined, and the mechanisms that are responsible for that effect were identified. The results show that the droplet-burning rate increases with increasing particle concentration. For example, with a 5 wt% addition of 80 nm aluminum nanoparticles, the burning rate increased by 140%. The burning rate enhancement is mainly attributed to strong radiation absorption of the nanoparticles suspended within the droplets, which provides more energy from the exothermic reaction (the flame) to the liquid phase (the droplets) for vaporization, thus increasing the burning rate. The radiation absorption effect becomes increasingly important as the droplet size increases.

Nanofluid PCMs for thermal energy storage: Latent heat reduction mechanisms and a numerical study of effective thermal storage performance

Abstract The latent heat of fusion of paraffin-based nanofluids has been examined to investigate the use of enhanced phase change materials (PCMs) for thermal energy storage (TES) applications. The nanofluid approach has often been exploited to enhance thermal conductivity of PCMs, but the effects of particle addition on other thermal properties affecting TES are relatively ignored. An experimental study of paraffin-based nanofluids containing various particle sizes of multi-walled carbon nanotubes has been conducted to investigate the effect of nanoparticles on latent heat of fusion. Results demonstrated that the magnitude of nanofluid latent heat reduction increases for smaller diameter particles in suspension. Three possible mechanisms – interfacial liquid layering, Brownian motion, and particle clustering – were examined to explain further reduction in latent heat, through the weakening of molecular bond structures. Although additional research is required to explore detailed mechanisms, experimental evidence suggests that interfacial liquid layering and Brownian motion cannot explain the degree of latent heat reduction observed. A finite element model is also presented as a method of quantifying nanofluid PCM energy storage performance. Thermal properties based on modified effective medium theory and an empirical relation for latent heat of fusion were applied as model parameters to determine energy stored and extracted over a given period of time. The model results show that while micro-scale particle inclusions exhibit some performance enhancement, nanoparticles in PCMs provide no significant improvement in TES performance. With smaller particles, the enhancement in thermal conductivity is not significant enough to overcome the reduction in latent heat of fusion, and less energy is stored over the PCM charge period. Therefore, the nanofluid approach may not be justifiable for energy storage applications. However, since the model parameters are dependent on the material properties of the system observed, storage performance may vary for differing nanofluid materials.

Electrolyte Uptake Kinetics in Doped and Undoped sol-gel Films Using a High Resolution EQCM Oscillator Sensor

The electrolyte uptake kinetics in hybrid sol–gel films was monitored with an electrochemical quartz crystal microbalance (EQCM) oscillator sensor, focused on the effect of particles addition in the film. Undoped and zinc oxide doped sol-gel coatings were immersed in a 0.1M NaCl solution to reproduce seafood environment with the object of study their performances as anti-corrosion coatings for the food packing industry. The electrolyte uptake process was investigated by immersion of doped and undoped sol-gel films in NaCl solution for 24hours. The acoustic load impedance, the shear modulus and the acoustic factor of the films were also calculated before and after immersion in order to determine the gravimetric regime of the sensor. Also, the phase noise performance of the oscillator in the solution was investigated to characterize the oscillator's resolution during the electrolyte uptake process.

Effect of Particle Addition on Degradation Rate of Methylene Blue in an Ultrasonic Field

Ultrasound has been found to be an attractive advanced technology for the degradation of hazardous organic compounds in water. In addition, the sonochemical reaction is enhanced by particle addition. However, the enhancement mechanism of particle addition has not been investigated well, because ultrasound enhances not only chemical reactions but also mass transfer. In this study, the ultrasonic degradation of methylene blue was carried out, and the effects of the ultrasonic irradiation condition on the degradation rate were investigated. The effect of ultrasonic frequency on the improvement of degradation by particle addition was also investigated. The order of degradation rate with frequency was the same as the tendency of sonochemical efficiency value obtained using KI oxidation dosimetry method (SEKI). The degradation process of methylene blue was intensified by particle addition, and the degradation rate increased with increasing amount of particle addition. The enhancement of degradation rate by particle addition was influenced by both ultrasonic frequency and type or diameter of particles.

Effect of particle additions on microstructure evolution of aluminium matrix composite

The study investigates the influence of different fractions of particles (1, 2.5, 5, 8 and 10vol.%) on microstructure of the as-extruded Al–Al4C3 composite as well as on the microstructure evolution at elevated temperatures and after cooling to room temperature. The results indicate that all the materials exhibit a stable microstructure up to 500°C. The excellent thermal stability is secured by the dispersed nano-particles that strengthen crystallite/grain boundaries by direct interaction of the particles with moving dislocations. In addition, the higher particle contents (8 and 10vol.%) help to suppress the deformation texture of the hot extruded solids and refine the matrix microstructure to a nanometric scale resulting in a marked enhancing of dislocation density and consequently hardness.

The antimicrobial effect of open-cell silver foams

Open-cell silver foams with various pore sizes (494, 337, 126 and 39 microm) and porosity (60, 70 and 80 vol%) were produced using a powder-based replication method. It was found that the foams have strong microbial reduction efficiency. The antimicrobial effect of the foams is much stronger on gram-negative bacterium (Escherichia coli) than gram-positive bacterium (Staphylococcus aureus). With equivalent volume addition of NaCl particles, higher antimicrobial effect was found for Ag foams with larger pore size. The difference on antimicrobial effect between silver foams with various pore sizes is smaller when porosity of the foams increases from 60 to 80%. No correlation between particle sizes of NaCl and bacterial growth inhibition was found. In addition, effect of particle sizes and pore sizes of the foams on the bacterial growth inhibition is not as much as the effect of particle addition. It is expected that the positively charged Ag ions released from the surface of Ag foam structure would alter the morphology of bacteria strains in which disruption of cell wall and eventually damage were implemented.

The effect of particle addition and fibrous reinforcement on epoxy-matrix composites for severe sliding conditions

This paper reports production and tribological testing of epoxy-matrix composites for dry-sliding conditions. The examined composites are produced using the following components: epoxy resin (EP), glass fiber weave (G), carbon/aramid hybrid weave (CA), PTFE particles and nano-scale CuO particles. Friction, wear and interfacial temperatures are measured on a custom-built pin-on-disk apparatus using a steel disk as counterface. The performance of the two types of reinforcing weaves are compared at nine different combinations of contact pressure ( p) and sliding velocity ( v ) also called p v conditions. The purpose is to systematically compare the performance of the differently reinforced materials while going from mild to severe sliding conditions. It is found that the coefficient of friction ( μ ) on average is reduced by 35% by substituting the glass fiber weave with the carbon/aramid weave. The latter, shows superior wear behavior at the six mildest p v conditions with the wear rate ( w ˙ ) an average factor of 22 lower than the rates for glass fiber reinforcement. An effect of fiber orientation with respect to sliding direction is found for the glass fiber reinforcement. The best tribological properties are seen when the fibers are parallel and anti-parallel (P–AP) to the sliding direction compared to normal and parallel (N–P). Experiments with incorporating micro-scale PTFE particles and nano-scale CuO particles, respectively, into the epoxy resin along with the carbon/aramid weave shows no difference in friction but minor improvements in wear. When micro-scale PTFE particles are incorporated into the neat epoxy resin, i.e. without fibers, an increase in w ˙ and a decrease in μ are measured. When the same is done with nano-CuO a deterioration of both friction and wear properties are seen. At the three roughest p v conditions all tested composites show signs of decomposition. Despite this, glass fiber reinforcement has a relatively steady behavior while carbon/aramid reinforcement gives raise to a gradually increasing frictional force, which ultimately results in complete failure of the test-specimen.

Effect of Particle Addition to Liquid Metal on Fabrication of Aluminum Foam

Effect of Particle Addition to Liquid Metal on Fabrication of Aluminum Foam

Effect of particle addition on sonochemical reaction

Enhancement of chemical reaction with a photocatalyst of titanium dioxide (TiO 2) by ultrasonic irradiation is studied through the absorbance measurements for liberation of iodine from a KI aqueous solution as an index of oxidation reaction. It is well known as a synergetic effect that the addition of TiO 2 fine particles under UV has an ability to enhance the yield in chemical reaction with OH-radical from hot spot at violent collapse of cavitation bubbles with intense ultrasound. In this study, the absorbance is measured after simultaneous irradiation of ultrasound and UV with the addition of TiO 2 much less than the usual concentration by two orders of content. It is shown that, even in case of quite a little TiO 2 addition where the photocatalytic effect is less, the yield is enhanced obviously in comparison with the summation in yield of independent procedure of ultrasound without TiO 2 and UV with TiO 2. The absorbance-peak deviation to the shorter wavelength implies the generation of titanium peroxide (TiO 3). The effect of particle addition is due to the chemically activated particle surface on the TiO 2 and probably to the increase in the cavitation bubbles that results in promoting a transfer of OH-radical and other oxidants to bulk liquid region at the collapse.

Effect of Particle Additions on Drying Stresses and the Green Density of Sol‐Gel‐Processed Three‐Dimensional Ceramic‐Matrix Composites

This paper investigates sol‐gel processing of three‐dimensional (3‐D) ceramic‐matrix composites, focusing on the effect of addition of particles on drying stresses and composite green density. A 3‐D woven carbon fiber/silica composite was used as the model material system for the investigation. Composites were fabricated with silica particle additions to the silica sol using a pressure infiltration technique, and the drying rate and matrix cracking were characterized. The particle size was varied in order to study the role of particle additions in the processing. Ammonium hydroxide (NH4OH) and a particle coating agent, 3‐(trimethoxysilyl)propyl methacrylate (TPM), were added in the mixture of particles and sol to improve particle packing in the preform. Sol‐gel processing with the addition of particles proves to be an effective route to fabricate 3‐D ceramic‐matrix composites with higher green density and less matrix cracking.