Effects Of Stirring Time Research Articles

Effect of stirring time on the mechanical behavior of friction stir spot weld of Al 6061-T6 lap-shear configuration

The effect of five different stirring times of friction stir spot welding on lap-shear specimens of Al 6061-T6 alloy has been experimentally analyzed. The welding condition with 2 s of stirring shows the optimum mechanical behavior in comparison to the others. The static strength and fatigue behavior of the joint are justified using the microhardness profiles. The static results prove that the increase of stirring time beyond the 2 s case has little effect on improving the static strength. The fatigue results reveal two different failure modes, which are shear fracture at high load levels and transverse crack growth at low load levels. At medium load levels, although the final failure is similar to high load levels, the transverse growth of the crack outside the welding zone, just like low load levels, is also observed.

Separation of phenolic compounds from oil mixtures using environmentally benign biological reagents based on Brønsted acid-Lewis base interaction

Phenolic compounds, which are widely used in producing synthetic fibers, engineering plastics, and other industrial organic chemicals, can be obtained from oil mixtures before further processing or applications by separation. Based on Lewis/Brønsted acid-base theory, we proposed the separation of phenolic compounds from oil mixtures using some environmentally benign biological reagents (BRs, including 1,3-dimethylxanthine-DMX, isonicotinamide-INA, and L-lysine-LYS). The effects of stirring time, temperature, initial phenol concentration, and BR:phenol mole ratio on phenol removal were studied in detail. LYS, INA and DMX show phenol removal efficiencies of 98.4%, 82.2%, and 66.6% from toluene at BR:phenol mole ratios of 1.6, 1.4, and 0.4, respectively, and those of 99.1%, 91.8%, and 74.6% from n-hexane at BR:phenol mole ratios of 2.20, 1.60, and 0.80, respectively, at room temperature. The BRs were regenerated with an anti-extraction method for four cycles without significant changes in separation efficiency and their properties. In addition, it is found that there is little toluene entrained in the biological reagents, which is as low as 2.3 wt% of separated phenol, indicating high purities of products. These BRs show the advantages of easy biodegradation, no corrosion to the equipment and containers, and no pollution to the environment.

Efficient separation of phenolic compounds from model oils by dual-functionalized ionic liquids

Four kinds of dual-functionalized ionic liquids (DFILs, [Et2NEmim][Cl]2, [Et2NEmmor][Cl]2, [Et2NEmpyr][Cl]2 and [Et2NEmpic][Cl]2) were synthesized and used to efficiently separate phenolic compounds from model oils. The effects of stirring time, temperature, mole ratio of DFIL to phenol and initial phenol content on the separation were investigated. The results indicate that at a DFIL:phenol mole ratio of 0.3, the content of phenol in the oil phase can reach the minimum value and the extraction efficiency of phenol is more than 96%. The minimum phenol content in the oil phase and the best phenol extraction efficiency were 5.9 g/m3 and 98.5%, respectively, when [Et2NEmpyr][Cl]2 was used. Compared with traditional ionic liquids, these DFILs not only reduce the dosage of extraction agents but also greatly decrease the content of Cl− in the oil phase due to the double anion in the DFILs. The DFILs can be reused for 4 cycles without losses in phenol extraction efficiency and masses of the DFILs. The separation mechanism of extraction was studied using FT-IR. The result indicates that the two anions Cl− on DFILs can form a hydrogen bond with phenol.

Effect of stirring time on oil agglomeration of fine coal

Effect of stirring time on oil agglomeration of fine coal

Effects of stirring parameters on the rheocast microstructure and mechanical properties of aluminum alloy ADC12

In this study, effects of stirring time and stirring speed on the microstructure of semisolid rheocast (SSR) aluminum alloy ADC12 were examined. The research method was done by gravity casting using a metal mold. The aluminum ADC12 slurry is stirred by a mechanical stirrer (round rod stirrer) at 610OC with a variation of speed 0, 250, 300, 350 rpm for 0, 20, 40, 60 seconds. Furthermore, the aluminum slurry of ADC12 is poured on a metal mold with temperature 600OC. The microstructure characteristics were examined by direct observation using optical microscopy, secondary -Al phase dendrite arm spacing, shape factor, and Si eutectic phase were identified. The mechanical properties were investigated by hardness test and tensile test. A short period of stirring below the liquidus temperature to form a non-dendritic structure. The final morphology of the primary particles after a short period of stirring time has little impact as the stirring time increases. The optimal mechanical properties (hardness and tensile strength) were obtained at 20 seconds of stirring time and 300 rpm of stirring rate.

Effect of stirring time on the structural parameters of nanophotonic LiNbO3 deposited by spin-coating technique

Lithium niobate (LiNbO3) photonic crystals are deposited on quartz substrate by using spin coating technique. The mixture is prepared with different stirring time (8 h, 24 h, 48 h). The LiNbO3 nanostructures are analyzed by X-ray diffraction. The results show that as mixing time increases, the XRD starts to become structurallymore regular and high crystallization, therefroe it is found that the best mixing time was 48 h related to ideal syntheiss. The effect of different annealing temperatures (400, 500, and 600 °C) on the structural properties is elaborated studied towards finding ideal conditions for the preparation of optical waveguides.

Highly efficient extraction of phenolic compounds from oil mixtures by trimethylamine-based dicationic ionic liquids via forming deep eutectic solvents

In this article, dicationic ionic liquids (DILs), including N,N,N,N′,N′,N′-hexaethyl-ethane-1,2-diammonium dibromide (HEDBr), N,N,N,N′,N′,N′-hexaethyl-propane-1,3-diammonium dibromide (HPDBr) and N,N,N,N′,N′,N′-hexaethyl-butane-1,4-diammonium dibromide (HBDBr), were designed and used to extract phenolic compounds from model oil and coal tar oil. The effects of stirring time, temperature, DIL:phenol mole ratio, and initial phenol concentration on the extraction of phenol were studied. It is found that the DIL:phenol mole ratio is only around 0.3 when the highest extraction efficiency of phenol is obtained. The extraction process completes within 5min at room temperature, and the extraction efficiency is not dependent on temperature. Also, the ultimate phenol concentration remains constant despite the difference in initial phenol concentrations. Of these DILs, HPDBr shows the lowest ultimate phenol concentration of 3.9g/dm3, and the extraction efficiency of phenol can reach as high as 97.0%. These DILs can be regenerated by anti-solvent method and reused several times without significant reduction in extraction efficiency. In addition, HPDBr was demonstrated to extract phenolic compounds from real coal tar oil, and its extraction efficiency of phenolic compounds is 92.7%. The mechanism, analyzed by FT-IR, shows that there is a hydrogen bond between phenol and DIL.

Effect of stirring time on morphology and crystalline features of MnO2 nanoparticles synthesized by co-precipitation method

ABSTRACTManganese oxide (MnO2) nanopowders were synthesized by a co-precipitation method. The X-ray diffraction results confirmed the formation of an α-MnO2 crystal with tetragonal structure, with the crystallite size decreasing as the stirring time is increased from 0.5 h to 3 h. Transmission electron microscopy investigation revealed that MnO2 powders consisted of nanorods with the average particles sizes of 20–80 nm diameter and 100–150 nm length. The lattice fringes thickness is 0.619 nm, which corresponds to the direction of (110) plane. Finally, it was found that the stirring time was the key parameter to control the morphology, particle sizes, and crystallite size of MnO2 powder.

Optimum Yield Parameters Of Mwcnt/Mno2 Nanocomposite

The objective of this study is to illustrate the optimum parameters adopted to evaluate maximum yield of MWCNT/MnO2 nanocomposite. In this paper, the effect of stirring time, Concentration of H2SO4 (aq) solution, solution temperature and drying time on yield of MWCNT/MnO2 nanocomposite was investigated. The orthogonal array, signal-to-noise ratio, and percentage contribution of all parameters are employed to study the yield of MWCNT/MnO2 nanocomposite. After conducting the experiments the yield was measured and Signal to noise ratio was calculated. With the help of graphs, optimum parameter values were obtained at parameter level A2B2C2D1. The percentage contributions of parameters and regression analysis confirmed the concentration of H2SO4 has significant effect on yield of MWCNT/MnO2 powder.

Effect of Stirring Time, Proofing Time and Water Content on the Aging of Steamed Bread

The effect of stirring time, fermentation time and moisture content on staling of steamed bread were studied. The absorbance, Aw and their correlations for different mixing time steamed bread were measured. The absorbance of steamed bread with different fermentation time was described after cold storage for 72 h. In addition, the effect of moisture content on the microstructure of steamed bread was analyzed by Scanning Electron Microscopy (SEM) and the staling rate was quantified by DSC and absorbance. The result shows that the staling rate of steamed bread increased with the moisture content. It also indicates that the staling rate of steamed bread is affected by mixing time and related to Aw. Besides, fermentation time also has an effect on the staling rate of steamed bread.

<b>Optimization of protein extraction process from jackfruit seed flour by reverse micelle system

The extraction of protein from flour of jackfruit seeds by reverse micelles was evaluated. Reverse micelle system was composed of sodium dodecyl sulfate (SDS) as surfactant, butanol as solvent, and water. The effects of stirring time, temperature, molar ratio H 2 O SDS -1 , concentration of butanol (mass percentage) and flour mass were tested in batch systems. Based on the adjusted linear regression model, only butanol concentration provided optimum extraction conditions (41.16%). Based on the analysis of surface response, the best extraction yield could be obtained at 25°C, stirring time of 120 min, mass of flour of 100 mg, and a ratio H 2 O SDS -1 of 50. Experimental results showed that a 79.00% extraction yield could be obtained.

Back Cover: Crystal Research and Technology 4'2014

Crystal Research and TechnologyVolume 49, Issue 4 Back CoverFree Access Back Cover: Crystal Research and Technology 4'2014 First published: 02 April 2014 https://doi.org/10.1002/crat.201470007AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Graphical Abstract ZnO exhibits the richest range of morphologies among the wide band gap semicionductorsand has been found plenty of applications in diversity fields. Here, X. L. Zhang and co-workers demonstrated how to form the various ZnO micro-, nano- structures by means of tuning the stirring time and ratio of the constituents. The effects of stirring time and ammonia contents on the morphology evolution of ZnO nanostructures and their growth mechanism have been discussed systematically. Volume49, Issue4April 2014 RelatedInformation

Surface‐morphology evolution of ZnO nanostructures grown by hydrothermal method

Surface‐morphology evolution of ZnO nanocrystals has been observed by the hydrothermal process. The effects of stirring time and ammonia content on the morphology evolution have been discussed, respectively. Extension of stirring time of the precursor results in morphology transformation from star‐like to wire‐like ZnO nanocrystals. ZnO nuclei aggregation and uniform Zn(OH)2 precipitation can readily explain these two morphologies, respectively. By increasing the ammonia content in the solution, the morphology of ZnO crystals is transformed from an irregular shape to hexagon sheets to nanorods, and the side length of ZnO crystals is decreased accordingly. Hollow structures are realized at the subsequent solution aging process. Variation of zinc ammonic complex and minimum surface energy can well explain the morphology evolution of ZnO nanostructures.

Microstructure and properties of metakaolin-based inorganic polymer foams

A mixture of 70 % metakaolin and 30 % blast furnace slag powders, employed as the raw material, is mixed with different alkaline activating solutions in the production of metakaolin-based inorganic polymer foams (MIPF) with various densities ranging from 0.4 to 1.0 g/cm3 using a mechanical foaming process. The microstructures of metakaolin and slag powders, inorganic binder, and MIPF specimens are characterized by using XRD, FTIR, and image analyses. The effects of stirring time, water/binder ratio, and foaming agent on the properties of inorganic binders are also evaluated. Moreover, the pore size distributions, thermal and mechanical properties of the MIPF specimens are obtained by conducting a series of measurements and then compared with each other. Based on the experimental results, it is found that the measured cell length, cell wall thickness, compressive strength, flexural strength, and coefficient of thermal conductivity of the MIPF specimens are significantly affected by their densities.

Adsorption of mercury from aqueous solution by nontronite, Aspergillus niger, and hybrid material

A natural nontronite clay sample from the Amazon region (Tocantins State, Serra da Messa Group, Brazil) was utilized for synthesis of a new biomaterial produced by a hybridization process of inorganic and organic materials. The new biomaterial was composed of an Amazon nontronite and fungal mass obtained from the Aspergillus niger fungus. The natural clay, biomass, and biomaterial samples were used in batch studies for adsorption of Hg2+ ions from aqueous solution. The effects of stirring time, adsorbent dosage, and pH on the adsorption capacity demonstrated that 70 min is sufficient to reach equilibrium at room temperature and over a pH range of 6.0–8.0. The maximum number of moles adsorbed was 9.47, 17.8, and 18.7 mmol g–1 for natural clay, biomass, and biomaterial, respectively. From the cation/basic center interactions for each material at the solid–liquid interface, by using calorimetry, the equilibrium constant and exothermic thermal effects were calculated. By considering the net interactive number of moles for mercury ion and the equilibrium constant, the enthalpy and negative Gibbs free energy could be calculated: ΔintH = −6.8 ± 0.11 to −6.0 ± 0.22 kJ mol–1; ΔintG = −20.5 ± 0.25 to −23.2 ± 0.22 kJ mol–1. The thermodynamic values indicated the existence of favorable conditions for interactions at the solid–liquid interface.

Preparation of Core-Shell Microspheres by Changing Reaction Solvent

We have successfully prepared monodispersed core-shell microspheres with polystyrene cores and poly(N-isopropylacrylamide) shells by changing solvent from nonpolar to polar for the first time. Effects of stirring time and reaction temperature on the particle size, monodispersity of the microspheres were investigated. With increasing stirring time at 800 rpm, the size of the spheres and the monodispersity are the best when stirring time is 60 min. And with increasing reaction temperature (above phase transition), the size of the microspheres decreases and the monodispersity becomes better.

The novel, one step and facile synthesis of ZnO nanoparticles using heteropolyoxometalates and their photoluminescence behavior

A novel and facile wet chemical method is presented to synthesize zinc oxide nanoparticles (NPs) under ambient atmosphere and temperature. Keggin type heteropolyoxometalate (H3[PW12O40]) was used as stabilizer and the effect of stirring time and amount of H3[PW12O40] (HPW) were studied. XRD and TEM techniques were applied for the morphological and structural characterizations of NPs. Size of nanoparticles were determined using TEM, Scherrer’s formula as well as effective mass approximation. The results of these three methods are in good agreements and revealed single hexagonal zincite type crystalline with average particle size in the range of 3–15nm. Photoluminescence behavior of the prepared sample shows a strong orange to red emission centred at about 620–635nm, a green emission at around 550nm and broad UV emission at around 400nm.

Kinetics and thermodynamics of Cr(VI) ion adsorption onto organo-bentonite from the Amazon region

A natural bentonite clay sample from the Amazon region (Amazonas State) was utilized for the synthesis of new hybrid materials (organo-bentonite) produced by the organofunctionalization process. The organo-bentonite types were composed of an Amazon bentonite sample, 3-aminopropyltrietoxisilane and 3,2-aminoethylaminopropyltrimetoxisilane. The natural bentonite and organo-bentonite samples were used in batch studies for the adsorption of Cr(VI) ions from aqueous solution. The adsorption data were fitted to equilibrium and kinetic models. The effects of stirring time, adsorbent dosage and pH on the adsorption capacity demonstrated that 90 min is sufficient to reach equilibrium at room temperature and over a pH range of 6.0–8.0, the batch results were confirmed by column method and show that the adsorption process of materials accorded with Redlich–Peterson, Sips, and Langmuir isotherm models. The exothermic enthalpic values reflected a favorable energetic process for chromium ions anchored in the material surfaces. The negative Gibbs free energy results supported the spontaneity of three adsorption reactions with Cr(VI) ions. The model of Adams–Bohart was used to analyze the adsorption experimental data and the model parameters were evaluated.

Leaching capabilities of iodine monochloride (ICl) and diethylenetriamine pentaacetic acid (DPTA) at different concentrations and pH for some major and trace metals from coal and coal fly ash

In the present study, coal from Chakwal (Pakistan) was leached with an aqueous solutions of iodine monochloride (ICl) and diethylenetriamine pentaacetic acid (DPTA) of different concentrations. The effect of stirring time, concentration and pH was studied on the leaching of different metals from coal. The physicochemical parameters indicated that the coal was of reasonably good quality. The results indicated that with increase in time duration, the extraction of metals increased. In most of the cases, metal concentration increased in the leachate with increasing the concentration of the leaching agents. DPTA was found to be the best leaching agent for most of the metals. Higher extraction of metals from coal fly ash indicated that coal organic matter has a pronounced effect on the leaching. Higher concentration of metals was extracted from virgin coal and coal fly ash at low pH (p > 0.00) as compared to high pH. DPTA extracted metals in higher concentration from virgin coal and coal fly ash at low pH as compared to ICl. Based on the present study, the most leached metals were Fe, Cu, Mn and the least were Pb, Ni, Cd and Cr.

Fabrication of Al/Al2O3 composites by in-situ powder metallurgy (IPM)

Abstract Al6061/Al 2 O 3 composites containing 15–40 vol.% of different-sized (37–276 μm) alumina particles were produced by in-situ powder metallurgy (IPM). In this method, the stir casting and powder metallurgy (PM) synthesizing processes are combined into an integrated net shape forming process. For the preparation of each powder mixture, alumina particles were added to the molten aluminum alloy, and the resulting slurry was stirred at a specified temperature for a predetermined time. During the stirring process, alumina particles disintegrated into the molten alloy, and subsequent quenching resulted in a mixture of alumina and aluminum alloy powder particles. These powder mixtures were cold pressed and then sintered. The effects of stirring time and temperature, along with the alumina content and particle size on the size distribution, microstructure and morphology of the aluminum particles produced were investigated. It was found that the finer aluminum powder particles were produced by increasing the alumina content and by decreasing both the stirring temperature (from 780 to 710 °C) and alumina particle size (within the range of 37–150 μm). A comparison of optical and SEM micrographs of aluminum particles produced by IPM, solid assisted melt disintegration (SAMD) and gas atomization revealed that pore-free and more spherical particles were produced by the IPM and SAMD methods. Moreover, a microstructural investigation of the final products proved that consolidated composites with high contents of well-distributed reinforcing particles could be fabricated by the IPM method.