Presence Of Al2O3 Nanoparticles Research Articles

Improving mechanical properties of FSWed AA6061-T6 joint by controlling microstructural changes through utilization of stationary shoulder tool in presence of Al2O3 nanoparticles and external cooling

Improving mechanical properties of FSWed AA6061-T6 joint by controlling microstructural changes through utilization of stationary shoulder tool in presence of Al2O3 nanoparticles and external cooling

Mechanical properties and corrosion behavior of titanium surface biocomposites reinforced with Al2O3 particles fabricated by friction stir processing

This study aims to investigate the effects of Al2O3 micro and nanoparticles on the microstructure, mechanical, and corrosion properties of the pure titanium surface biocomposites fabricated by friction stir processing (FSP). The microstructure, mechanical, and corrosion properties of samples were evaluated using optical microscopy (OM), electron-backscattered diffraction system (EBSD), hardness tests, tensile tests, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) analyses. The OM and EBSD analyses proved the highest amount of grain refinement associated with the formation of strain-free recrystallized grains by applying FSP at the presence of Al2O3 nanoparticles. However, the amount of micro-strain and grain size of FSPed titanium without particles and with Al2O3 microparticles were much higher than that of samples with Al2O3 nanoparticles. Notably, the hardness values improved by about 33 % and 52 % by introducing Al2O3 microparticles and nanoparticles, respectively. Mechanical tests demonstrated a noticeable enhancement in the tensile strength of the samples, from 200 MPa for the sample processed without Particles to the highest amount of 294 MPa for that processed in presence of nanoparticles. The corrosion test results revealed a significant improvement in the corrosion resistance of the titanium samples by adding Al2O3 nanoparticles in which the corrosion potential increased from 0.244 to 0.192 V and charge transfer resistance from 394 to 794 kΩ cm2.

Influence of nanoscale objects on grain processing: results of mashing in the presence of Al2O3 nanoparticles

The article considers the influence of nanoscale objects on grain raw materials processing on the example of beer wort preparation. The effect of aluminum oxide nanoparticles present in the mash on the first wort indicators (concentration of dry and reducing substances, amine nitrogen) obtained by infusion or single-decoction mashing was studied. It was revealed that the influence of Al2O3 nanoparticles depends on their concentration, the object of influence and the method of preparation of beer (first) wort. The most sensitive to the presence of aluminum oxide nanoparticles under the experimental conditions were saccharifying hydrolases of grain raw materials. That caused the greatest fluctuations in the concentrations of reducing substances in the test samples of the first wort. Nanoparticles had the least pronounced effect on grain proteases, as a result fluctuations in the concentration of amino acid nitrogen in the experimental variants of the first wort were the smallest. When obtaining beer wort by the infusion method, the effect of nanoparticles was more pronounced than in single-decoction mashing. The concentrations of aluminum oxide nanoparticles were revealed, the excess of which led to a significant deterioration in the controlled parameters of the first wort - 1.5-2 mg/cm3, depending on the method of mashing.

Effect of CeVO4/Al2O3/rGO nanocomposite on rheological properties and thermal conductivity of water-based drilling fluid

In this research, in order to improve the rheological properties and thermal conductivity of the drilling fluid, CeVO4/Al2O3/rGO nanocomposite was synthesized by one-step hydrothermal method for the first time. In addition to controlling the growth of Al2O3, CeO2, and CeVO4 nanoparticles, hydrazine reduces graphene oxide (GO) to reduced graphene oxide (rGO) and enables one-step synthesis. The effect of nanoparticles (NPs) with concentrations of 0.01, 0.03, 0.05, 0.1, and 0.5 wt% on water-based drilling fluid was determined. In all samples, the shear thinning behavior of mud-containing nanoparticles was maintained at different shear rates. After adding 0.5 wt% of CeVO4/Al2O3/rGO nanocomposite, there was only 6 ml of lost circulation. By using CeVO4/Al2O3 nanocomposite, the plastic viscosity (PV) was tripled by increasing the concentration from 0.01 to 0.5 wt% so that PV for CeVO4/Al2O3 nanofluid with a concentration of 0.5 wt% increased to 12 cP. Thermal conductivity and gel strength in all samples were significantly improved, especially in the presence of Al2O3 nanoparticles. Thermal conductivity for liquid containing 0.5 wt% Al2O3 at 80 °C increased from 0.60 to 0.81 W/mK. In general, nanoparticles in concentrations less than 0.5 wt% Bentonite-WBMs (water-based muds) can improve rheological properties, filtration, and thermal conductivity.

Different Impact of Suspended Al2O3 Nanoparticles on Microbial Communities: Formation of 2D-Networks (Without Humic Acids) or 3D-Colonies (With Humic Acids).

The use of metal-based and, particularly, Al2O3 nanoparticles (Al2O3-NP) for diverse purposes is exponentially growing. However, the growth of such promissory market is not accompanied by a parallel extensive investigation related to the impact of this pollution on groundwater and biological systems. Pseudomonas species, ubiquitous, environmentally critical microbes, frequently respond to stress conditions with diverse strategies that generally include extracellular polymeric substances (EPS) formation. The aim of this study is to report that changes in the aqueous environment, particularly, the addition of Al2O3-NP without and with humic acids, induce different adaptive strategies of Pseudomonasaeruginosa early biofilms. To this purpose, early biofilms were incubated in diluted culture media without (control) and with Al2O3-NP, and with humic acids (HA-control, HA-Al2O3-NP) for 24h. 3D colonies with EPS strings and isolated bacteria in their surroundings were detected in the control biofilms. Unlikely, an unusual adaptive behaviour was developed in the presence of Al2O3-NP. Bacteria opt to disassemble the 3D arrangements and to implement a 2D network promoting morphological and size changes of bacterial cells (small coccoid shapes). Remarkably, this strategy allows their temporarily non-EPS-depending survival without decreasing the number of cells. This behaviour was not observed with ZnO-NP, HA-Al2O3-NP, or HA-ZnO-NP. Physicochemical analysis revealed that HA were adsorbed on Al2O3-NP and promoted the Al(III) ions complexation. This supports the hypothesis that the reduction of toxicity of Al ions and the 3D colony formation in the presence of HA-Al2O3-NP is promoted by the complexation of the metal ions with HA components.

The effect of variable temperature and location on relative thermal conductivity (RTC) on the heat pipe in the presence of AL2O3 nanoparticles: Numerical and optimization approaches

BackgroundThe cooling system is one of the important parts of new devices such as smartphones, servers, and other electrical devices. By employing the almost all heat transfer methods such as conduction, evaporation and condensation, heat pipes are the best choice to increase the heat transfer. The thermal conductivity of heat pipe is much higher than fins because they benefit from condensation and evaporation simultaneously. MethodsThis study tries to present relative thermal conductivity base on temperature and length of a heat pipe in optimized geometry. To achieve this aim, unsteady, multiphase fluid was considered inside the heat pipe. Evaporation, condensation, and conduction were assumed in the multi-functional simulation domain. Its also a combination of finite volume and differential evolutionary involved in simulation. This approach could improve the heat transfer efficiency and reduce the range of variables. FindingsThe numerical simulation of the evaporation and condensation indicated that relative thermal conductivity could improve the heat transfer accuracy of prediction Compared with standard methods up to 8%. The result also shows that by increasing the heat flux, relative thermal conductivity can play more efficient than constant thermal conductivity on the variation of Nu.

Impact of aluminium oxide nanoparticles as an additive in diesel-methanol blends on a modern DI diesel engine

The development of nanotechnology makes nanoparticle additives for internal combustion engines possible and the existing research results have shown that the engine performances can be improved with metal-based nanoparticles additive in the fuel. The present study makes an attempt to add aluminium oxide (AL2O3) nanoparticles (25, 100 ppm) into diesel-methanol blends, and to study the impact of the nanoparticle additive on the characteristics of a modern DI diesel engine. The results showed that the presence of AL2O3 nanoparticles in the diesel-methanol blends improved the peak in-cylinder pressure, heat release rate and brake thermal efficiency by 2.5%, 16.1% and 3.6%, respectively, as compared with those without AL2O3 additives, as well as the decreases in the ignition delay and combustion duration by up to 6.9% and 16%. And the brake specific fuel and energy consumption can be reduced by up to 3.7% and 3.5%, respectively. Moreover, engine emission tests showed the suppressions in CO, HC and smoke emissions by up to 83.3%, 40.9% and 69.2%, respectively, but a marginal increase in NOX emission by 14.4%. These results indicate that the presence of nanoparticle additives in the diesel-methanol blends can achieve sound effects of energy conservation and emission reductions.

Enhancement mechanisms of mass transfer performance by nanoabsorbents during CO2 absorption process

In this study, the hydrodynamic characteristics and enhanced mass transfer performance of CO2 absorption in the presence of Al2O3 nanoparticles are studied. A combined VOF-DPM model that can predict the characteristics of nanoparticles in gas–liquid system is developed. The gas bubble and liquid are modeled as the Eulerian phases by the volume-of-fluid (VOF) method, while the nanoparticles are tracked as the Lagrangian phase by the discrete particle model (DPM). The coupling interaction between phases was considered by adding the interchange terms to the momentum equation. Then a systematization of phenomena on both liquid and gas field that related to the motion of nanoparticles was presented, involving the turbulence in local liquid, dynamical deformation of gas bubble, and the distribution of gas velocity. Accordingly, the enhanced interfacial mass transfer was predicted and verified by experimental results. It was found that the interfacial flow, that is, the local turbulent motion of liquid, makes it possible for the nanoparticles to penetrate into the bubble surface. The penetrating particles, on one hand, disturb the velocity distribution inside the bubble, improving the fluid renewal at the gas–liquid interface. On the other hand, they play a shuttle role to carry CO2 gas between the gas phase and the interface. Finally, it is concluded that the nanoparticle-induced hydrodynamic effect dominates the CO2 absorption by improving the interfacial mass transfer.

Study on Hardness and Shear Strength with Microstructure Properties of Sn52Bi/Cu + 1% Al2O3 Nanoparticles

The Sn-58Bi (SB) lead-free solder was added with 1% nanoparticles (NP) of aluminium oxide (Al2O3) to investigate the shear strength based on microstructure and joint properties. The microstructures of the SB added with 1% Al2O3 NP containing Bi precipitation and β-Sn grains. The spacing between the lamellar structures of a SB solder alloy was narrower. Proper arrangement of the microstructure of β-Sn, Bi and with the presence of Al2O3 as discrete particles (dispersion strengthening) contributes to the increase on the shear strength and hardness value. The shear strength of the SB added with 1% Al2O3 NP solder joint was enhanced by 50% compared to the bare SB solder joint while there was a 33% increase in the microhardness as well. The shear test was conducted based on ASTM D1002 specification of single lap joint method. The presence of Al2O3 NP along the interface (Hall-Petch effect) contributes to the improvement in the shear strength by reducing the thickness of the IMC layer and retarding the growth of the Cu6Sn5 IMC layer. This study provides evident results for the enhancement of the mechanical properties of the 1% Al2O3 NP added SB solder.

Numerical investigation of Al<SUB align=right>2O<SUB align=right>3 nanoparticle effect on a boiling forced swirl flow field: application to the ITER project

One of the most important issues in design of the nuclear fusion power plants is the heat removal from the hottest region at the divertor. Various methods could be employed in order to improve the heat transfer efficiency such as generating turbulent flow and injection of nanoparticles in the host fluid. In the current study, water/Al2O3 nanofluid forced swirl flow boiling has been investigated by using homogeneous thermophysical model within Eulerian-Eulerian framework through a twisted tape tube and boiling phenomenon was modelled using the Rensselear Polytechnic Institute approach. In addition to comparing the results with the experimental data and their reasonable agreement, it was evidenced that higher flow mixing results in more uniform bulk temperature and lower wall temperature along the twisted tape tube. The presence of Al2O3 nanoparticles in the boiling flow field showed that increasing the nanoparticle concentration leads to a reduced vapour volume fraction and wall temperature.

CFD Investigation of Al2O3 Nanoparticles Effect on Heat Transfer Enhancement of Newtonian and Non-Newtonian Fluids in a Helical Coil

Abstract The present study applied computational fluid dynamics (CFD) to investigate the heat transfer of Newtonian (water) and non-Newtonian (0.3 %wt. aqueous solution of carboxymethylcellulose (CMC)) fluids in the presence of Al2O3 nanoparticles. To analyze the heat transfer rate, investigations were performed in a vertical helical coil as essential heat transfer equipment, at different inlet Reynolds numbers. To verify the accuracy of the simulation model, experimental data reported in the literature were employed. Comparisons showed the validity of simulation results. From the results, compared to the aqueous solution of CMC, water had a higher Nusselt number. In addition, it was observed that adding nanoparticles to a base fluid presented different results in which water/Al2O3 nanofluid with nanoparticles’ volume fraction of 5 % was more effective than the same base fluid with a volume fraction of 10 %. In lower ranges of Reynolds number, adding nanoparticles was more effective. For CMC solution (10 %), increasing concentration of nanoparticles caused an increase in the apparent viscosity. Consequently, the Nusselt number was reduced. The findings reveal the important role of fluid type and nanoparticle concentration in the design and development of heat transfer equipment.

Application of three nanoparticles (Al2O3, SiO2 and TiO2) for metal-contaminated soil remediation (measuring and modeling)

The immobilization of zinc (Zn), cadmium (Cd) and nickel (Ni) using nanoparticles (NPs) was investigated. Two non-calcareous and calcareous contaminated soils were incubated with Al2O3, SiO2 and TiO2 at 1 and 3% wt for 30 days at 25 °C in field capacity moisture and then were fractionated by the sequential extraction procedure. After application of NPs, a significant increase in metals was observed in residual (RES) fraction. The maximum reduction in exchangeable (EXC) Cd fraction was measured in soil treated with 1% Al2O3 (38.3%) and 3% SiO2 (56.1%) for non-calcareous and calcareous soils, respectively. The highest decrease in EXC Zn fraction in non-calcareous and calcareous soils was 28.8% for Al2O3 (3%) and 57.1% TiO2 (3%) treatments, respectively. Interestingly, non-calcareous soil showed a higher capacity to reduce Ni in available fractions and it decreased on average by 14.0% and 11.0% for non-calcareous and calcareous soils, respectively. In general, SiO2 NPs were an effective sorbent for immobilizing three metals in calcareous soils, while in non-calcareous soils the maximum reduction in mobile fraction of Cd and Zn occurred in the presence of Al2O3 NPs, and the shift from mobile to stable fractions of Ni was higher in soils containing SiO2 NPs. Similar to experimental data, the model predicted that NPs could reduce metal in EXC, carbonate (CAR), oxide (OX) and organically bound (OR) fractions. Results suggested that NPs can be effectively used for metal immobilization in multi-metal-contaminated soils and that surface complexation modeling (PHREEQC) could describe different fractions of metal in soils.

An influence of Al2O3 nanoparticles on the caloric properties and parameters of the phase transition of isopropyl alcohol in solid phase

In present paper we investigated the influence of Al2O3 nanoparticles on the specific heat capacity of isopropyl alcohol in the temperature range 80–186 K. The measurements of the specific heat capacity were performed by an adiabatic calorimeter. It was found that below the melting temperatures the solution of isopropyl alcohol with Al2O3 nanoparticles can be in crystalline, glassy and liquid metastable states. The presence of Al2O3 nanoparticles in isopropyl alcohol leads to a decrease of the specific heat capacity and the enthalpy of phase transitions “crystalline state – liquid” and “glassy state – liquid metastable state”. It was demonstrated that not only presence of the nanoparticles but also the existence of the adsorbed interfacial phase from the molecules of the base liquid around the nanoparticles decreases the isopropyl alcohol melting heat. Based on obtained experimental data for the melting heat of the nanofluids of isopropyl alcohol/Al2O3 the mass fraction of the base fluid in the interfacial phase and the mean equivalent radius of nanoparticles with interfacial phase have been determined at the melting point.

EFFECTS OF ALUMINUM PHOSPHATE CONTAINING Al2O3 NANOPARTICLES ON THE MECHANICAL PROPERTIES OF THE Al2O3-TiO2 PLASMA SPRAYED COATING

In the present study, Al2O3-40% TiO2 composite coatings were fabricated on CT3 steel substrate by plasma spraying technique. The coatings were sealed with aluminum phosphate solution contained 5 wt.% Al2O3 nanoparticles and then heat treated at 400oC. The permeability of aluminum phosphate solution, phase composition, structure morphology, microhardness and wear resistance of the coating were studied. The study results phase composition of the coatings showed that the coatings were composed γ-Al2O3 and Al2TiO5 phase. The compounds AlPO4 and Al(PO3)3 were found in the coating sealed with aluminum phosphate. The presence of Al2O3 nanoparticles was increased the permeability of the aluminum phosphate solution into the coating. The coatings sealed with aluminum phosphate contained Al2O3 nanoparticles have lower density, higher hardness and wear resistance higher than the coating sealed with aluminum phosphate uncontain Al2O3 nanoparticles and the unsealed coating.

Experimental investigation of minimization in surfactant adsorption and improvement in surfactant-foam stability in presence of silicon dioxide and aluminum oxide nanoparticles

Foams stabilized by a mixture of nanoparticles and surfactants are presently being considered for improving the poor macroscopic sweep efficiency of gas enhanced oil recovery (EOR) methods. The stability of these foams is influenced by the adsorption and foaming properties of the nanoparticles-surfactant mixtures. This study investigates the influence of silicon dioxide (SiO2) and aluminum oxide (Al2O3) nanoparticles on sodium dodecyl sulfate (SDS) adsorption on kaolinite and SDS-foam stability at static and dynamic conditions. The adsorption experiments were conducted by surface tension and two-phase titration methods. Adsorption data were analyzed by fitting with Langmuir, Freundlich and Temkin adsorption isotherms. Influence of salt on foam performance was investigated from bulk stability experiment conducted using KRÜSS dynamic foam analyzer. The pore scale visualization experiments were carried out with etched glass micromodels to study foam stability in porous media. Results show that SDS adsorption on kaolinite reduced by 38% in presence of Al2O3 nanoparticles and 75% in presence of SiO2 nanoparticles. The Langmuir isotherm model suits the equilibrium adsorption of sole SDS and Al2O3-SDS onto kaolinite while the Freundlich isotherm model suits the adsorption of SiO2-SDS onto kaolinite. Foam stability decreased in presence of salts until the transition salt concentration. Beyond the transition salt concentration, foam stability generally increased with the increasing salt concentrations. The presence of Al2O3 and SiO2 nanoparticles increased the foam half-life and decreased the transition salt concentrations. The dominant mechanisms of foams flow process were identified as lamellae division and bubble-to-multiple bubble lamellae division. The dominant mechanisms of residual oil mobilization and displacement by foam were found to be direct displacement and emulsification of oil. The identified pore scale mechanisms were independent of the pore geometry of the etched glass micromodels. There was lamellae detaching and collapsing during the flow process of SDS-foam in presence of oil which resulted in poor microscopic displacement efficiency. The SiO2-SDS and Al2O3-SDS foams propagated successfully in porous media in presence of oil with almost 100% microscopic displacement efficiency due to the enhanced films interfacial elasticity. The findings of this research provide an insight into surfactant adsorption minimization and pore-scale mechanisms of foam stability improvement by nanoparticles.

An experimental investigation of ignition probability of diesel fuel droplets with metal oxide nanoparticles

The aim of this study is to investigate the effects of nanoparticles type, nanoparticles size, and droplet size on the ignition probability of the diesel fuel. Also, the effect of metal oxide nanoparticles on the ignition delay of diesel fuel droplets is studied. A series of hot plate ignition tests are conducted for diesel fuel with and without Al2O3, TiO2 and Fe3O4 nanoparticles at different concentrations (up to 0.05wt.%). The experimental results show that the ignition probability of the diesel fuel significantly increases in the presence of metal oxide nanoparticles. The ignition probabilities of diesel/Al2O3 and diesel/Fe3O4 nanofuels are almost similar and higher than that of diesel/TiO2 nanofuel. Results for diesel/Al2O3 show that the nanoparticle size does not affect the ignition probability of nanofuel. Moreover, results indicate that the ignition probability decreases by increasing the droplet size. Investigations show that the ignition delay for diesel fuel droplets decreases in the presence of Al2O3 nanoparticles.

PANI-derived polymer/Al2O3 nanocomposites: synthesis, characterization, and electrochemical studies

This paper presents the physicochemical, conductive, and electrochemical properties of different polyaniline (PANI)-derived polymer/Al2O3 nanocomposites synthesized by chemical oxidation polymerization method carried out in two stages: first, activation of the surface of the Al2O3 nanoparticles by hydrochloric acid and second, polymerization of 2-chloroaniline (2ClANI), aniline (ANI), and the copolymer (2ClANI-ANI) in the presence of Al2O3 by using ammonium persulfate as oxidant in aqueous hydrochloric acid. XRD and TEM results reveal the growth of the polymers on Al2O3 nanoparticles and the formation of PANI-derived polymer/Al2O3 nanocomposites. FTIR and UV-Vis show a systematic shifting of the characteristic bands of the polymers with the presence of Al2O3 nanoparticles. Moreover, these nanoparticles enhance the thermal stability of the polymers, as found by thermogravimetric analysis (TGA). Although the incorporation of Al2O3 nanoparticles reduces the electric conductivity of the polymers, the resulting nanocomposites still keep high conductivities, ranging between 0.3 × 10−2 and 9.2 × 10−2 S cm−1. As a result, the polymer/Al2O3 nanocomposites exhibit a good voltammetric response. All these synergetic features of the nanocomposites are assigned to the effective interaction of the polymers and Al2O3 particles at nanoscale.

Fabrication and characterisation of copper–alumina nanocomposites prepared by high-energy fast milling

Two different methods are used to prepare Cu–20 vol-% Al2O3 nanocomposite powders via high-energy planetary fast milling. In the solid solution method, CuO powder was added to the Cu–Al solid solution powder, and the composite was fabricated by milling after 100 h. In the direct mixing method, Cu and Al2O3 powders were mechanically milled via high-energy planetary fast milling for 100 h. The transition electron micrographs (dark and white fields) revealed the presence of Al2O3 nanoparticles in crystalline Cu matrices for both methods. However, the density and bending strength of the nanocomposites produced via the solid solution method were higher than those of the samples produced via the direct mixing method.

Combined Cold Expansion and Friction Stir Processing of Fastener Holes in Aluminum Alloy Al-2014-T6

Cold expansion is used to induce compressive stress zone, by inserting a tapered mandrel/pin or ball into an undersized fastener hole in order to improve fatigue life. In this paper, combined cold expansion and friction stir processing of fastener holes in aluminium alloy Al-2014-T6 is presented wherein the cold expansion tool rotates and thus friction stirs the cylindrical surface of a fastener hole while expanding it. The residual stress, surface roughness and hardness of wall of fastener holes are measured and SEM images are captured. The combined cold expansion method is evaluated for three conditions at tool and fastener hole interface, namely wet (i.e., in presence of metal working fluid), solid lubricant (i.e., in presence of Al2O3 nanoparticles), and dry (i.e., without any external medium). The conventional cold expansion process is compared with combined cold expansion and friction stir processing. The results indicate efficacy of using nanoparticles as a medium in combined cold expansion and surface processing of Al-2014-T6 aluminium alloy to improve surface integrity and fatigue life.

Synchrotron radiographic studies of ultrasonic melt processing of metal matrix nano composites

Fast synchrotron radiography was used to investigate ultrasonic cavitation bubble formation and their dynamics during liquid metal processing of Al–Cu metal matrix nano composites (MMNC) in comparison with conventional alloys. The experimental observations showed enhanced cavitation potential in MMNC melts, due to the presence of Al2O3 nano particles which were believed to be acting as heterogeneous nuclei for bubble formation. Quantitative image analysis demonstrates that the addition of nano particles increases melt agitation partially, while introducing higher flow velocity variations across the melt. This suggests that the presence of nano particles may substantially alter propensity for ultrasonic treatment effects during solidification processing of MMNCs.