Ultrasonic Mixing Technique Research Articles

Influence of graphene oxide properties, superplasticiser type, and dispersion technique on mechanical performance of graphene oxide-added concrete

The incorporation of Graphene Oxide (GO) nanomaterial into concrete has gained significant attention due to its potential to enhance mechanical and durability properties. The addition of GO to concrete creates considerable changes in the morphology of the concrete matrix, creating a densified microstructure. Critical parameters significantly affect these microstructural enhancements and, consequently, the final performance in GO-added concrete. These parameters include GO material properties, superplasticiser (PS) type, and dispersion techniques. Therefore, this study investigates the influence of GO on the mechanical performance of concrete, focusing on these critical factors. Unlike existing studies concentrating on a single parameter's effect, this research comprehensively compares how these parameters impact GO-added concrete. Two commercially available GO types (GO-A and GO-B) and two PS types (PS-A and PS-B) are utilised. At the same time, three commonly used mixing techniques, such as mechanical, high-speed, and ultrasonic mixing techniques, are considered for GO dispersion. GO-A is added to concrete in percentages ranging from 0.02% to 0.14% by weight of cement (bwoc), while GO-B ranges from 0.04% to 0.20% bwoc. Based on compressive strength test results, the optimum GO dosages are 0.08% for GO-A and 0.12% for GO-B. The highest strength results are achieved for GO-B added concrete with PS-A addition and following the ultrasonic dispersion method, highlighting these parameters as optimal for maximising GO-added concrete performance. The optimum concrete mix exhibits 33%, 24%, 25%, and 30% increments for compressive strength, indirect tensile strength, flexural strength, and elastic modulus properties at 28 days. This paper provides a deep theoretical explanation of the effects of GO material properties, dispersion techniques, and PS type on GO-added concrete performance. The findings provide valuable insights into selecting suitable parameters for optimising the mechanical properties of GO-added concrete, contributing to the advancement and effectiveness of construction materials.

Tension evaluation of prestressed strand based on combined features of nonlinear ultrasonic mixing

The estimation of prestressed strand stress levels is of great significance in ensuring the structurally reasonable performance of post-tensioned concrete structures, cable-stayed bridges, and arch bridges. This paper proposes a method to evaluate the remaining tensile stress on the strand through the ultrasonic mixing technique. The relationship between the strand tension and the nonlinear harmonics is established based on the theory of contact acoustic nonlinearity, and the acoustic nonlinear parameters at different tension levels are investigated by finite element analysis and step-loading experiments. The results show that the nonlinear parameters follow a power-law decrease with the increase in the tensile stress. To overcome the shortage of decreasing sensitivity of theoretical nonlinear parameters in monitoring early loosening, support vector regression is introduced to utilize complex high-order nonlinear generations in stress evaluation. With this approach, the accuracy of early-stage stress evaluation based on wave mixing has been remarkably improved.

Design, preparation, and performance of a novel organic–inorganic composite coating with high adhesion and protection for concrete

To guarantee concrete serving in harsh and corrosive environments, a novel functional organic–inorganic composite coating with high adhesion and barrier performance was designed in this work. The prepared composite coating was assembled by incorporating kaolinite nanosheets into permeable epoxy resin via ultrasonic mixing techniques. The dispersed nanosheets endowed the epoxy with reinforced cross-linking, high temperature stability and enhanced barrier property. The composite coatings exhibited stable bonding with the concrete matrix and excellent corrosion resistance. The composite coating with 1 wt% nanosheets showed an optimum comprehensive performance. It could infiltrate concrete with a depth of 2376 μm and the dehydration reaction temperature of the coating was 168.1 °C. The total charge passed and maximum oxygen transmission was reduced to 63C and 4.438 cc/m2 day, respectively. The pull-off strength of the composite coating with concrete was 5.68 MPa, which was 32% higher than the permeable epoxy. The designed composite coatings provided strong bonding and high barrier to the concrete structure, showing potential application in the anti-corrosion engineering and construction field.

Determining influences of different stirring methods for encapsulating stearic acid with SiO2 shell for thermal energy storage applications

ABSTRACTStearic acid was encapsulated successfully with SiO2 shell in nanoscale by in situ emulsion interfacial hydrolysis and poly-condensation techniques. The influence of using different mixing techniques on these techniques was investigated. Morphologic, thermal and crystal structure analysis results show that the ultrasonic mixing technique is suggested for synthesis of SiO2 nanocapsules. Ultrasonic vibrations lead to more homogeneous covering of the oil droplets without residuals by effectively orienting SiO2 molecules during polymerization.

Mechanical properties enhancement of self-cured PMMA reinforced with zirconia and boron nitride nanopowders for high-performance dental materials

We report on the mechanical properties regarding self-cured acrylic polymethyl methacrylate (PMMA) reinforced with hexagonal boron nitride (h-BN) and stabilized zirconia (8Y ZrO2) nanopowders. The nanocomposites were prepared by using both manual and ultrasonic mixing techniques. The fabricated specimens were subjected to micro indentation, bending strength, and modulus of elasticity measurements. A fully complete polymerization process under liquid monomer was provided by ultrasonic mixing as evidenced by Fourier transform infrared (FTIR) measurement. Independently of the nanopowder used, the hardness, bending strength, and modulus of elasticity of the formed nanocomposites highly increase in values with the increase of the filler concentrations. Higher bending strengths and modulus of elasticity of the nanocomposite were recorded when using h-BN nanopowder fillers whereas hardness increases when using 8Y ZrO2 nanopowder. Results showed that with respect to the unloaded specimens made by manual mixing, ultrasonic mixing of PMMA with a 5 wt% h-BN increased the flexural strength (FS) and the modulus of elasticity or Young's modulus (YM) values to about 550% and 240%, respectively. However, a similar concentration of 8Y ZrO2 increased the Vickers Hardness numbers (VH) to about 400%. This may suggest that PMMA loaded with a combination of h-BN and 8Y ZrO2 nanopowders may lead to nanocomposites with outstanding mechanical performance.

Polyaniline (PANI) and BaTiO3 composite nanotube with high suspension performance in electrorheological fluid

In this research, one-dimensional polyaniline/barium titanate (PANI/BaTiO3) composite nanotubes with core-shell structure were synthesized by hydrothermal treatment, and the surfaces of the nanocomposites were modified with 3-aminopropyltriethoxysilane. The TGA measurement results showed the thermal stability of this nanocomposite was improved compared with pure polyaniline, indicating the deposition of polyaniline on the surface of BaTiO3 nanotubes, which was confirmed by the characterizations and morphology analyses of SEM, FTIR, and XRD. Furthermore, a new electrorheological (ER) fluid was obtained by dispersal of polyaniline/barium titanate nanotubes in silicone oil by ultrasonic mixing technique. The nanotube-based ER fluid exhibited higher suspension stability than original nanoparticle ER fluid. Only insignificant sedimentation was found in this nanotube suspension even several months later. This fluid showed a notable ER behavior with the electric field affection, which was caused by the microstructure change induced by polarization among nanotubes; these observations were well interpreted by analyses of the flow curve, static yield stress, and dynamic test. The results of this study provide possible ways to synthesize ER fluid with good suspension stability and high ER activity by 1-D nanotubes and would help to investigate the potential application of ER fluid in practical realm of waste water treatment.

Assessment of Mechanical and Thermal Properties of Juniperus Drupacea/Epoxy Biocomposite

This paper presents experimental data using estimated approach to determine some mechanical properties of epoxy matrix based composites. For this reason, the epoxy matrix was combined with the powdered materials obtained from different parts of the juniperus drupacea seeds. In order to obtain a homogeneous structure ultrasonic mixing technique was preferred. The Taguchi method is an alternative way to characterize complex composite structures, to come from above the problems and to investigate the effects of test parameters-factors by performing a few experiments. In the study, the L9 Taguchi orthogonal array has been preferred. Based on some production conditions; bio-reinforcement material has lowered the average hardness value to 4.22 and formed a more soft structure in addition to improving the tensile strength value by 46% compared to the neat sample. Parametric study showed that; the most important parameter affecting hardness and tensile strength are the mixing time and reinforcement ratio, respectively.

유도초음파 혼합 기법을 활용한 재료 부식 평가 연구

원거리를 전파하는 유도초음파의 특성을 활용하여 광범위한 영역의 재료 손상을 위한 연구를 수행하였다. 유도초음파의 모드별 전파 특성을 반영하기 위해 각 모드별 변위분포를 계산하였다. 표면변위의 비율이 최대가 되는 모드를 선정하고 혼합 파형이 생성되는 주파수가 잘 나타날 수 있는 속도를 선정하였다. 혼합 모드가 생성되고 진폭이 최대가 될 수 있는 조건으로 입사 주파수를 선정하여 혼합 모드가 생성되는 것을 확인하였다. 혼합모드의 전파 특성을 활용하여 알루미늄 5052재료의 표면 부식 진단을 위한 실험을 수행하였다. 기존의 유도초음파 음향 비선형성을 활용한 진단 기법과 유도초음파 혼합 기법을 비교하여 표면 부식 결함 진단 민감도를 확인하였다.

Improvement of Chemical and Thermal Properties of Polyethylene Terephthalate (PET) by Using Multi-walled Carbon Nanotubes (MWCNTs)

This work aims to investigate the improvements of thermal and chemical properties of polyethylene terephthalate (PET) by using Multi-walled carbon nanotubes (MWCNTs). MWCNT were used as a reinforcement in polyethylene terephthalate with different weight percentages (0.1, 0.5, and 1) % respectively. The direct mixing process was used to prepare (polyethylene terephthalate / MWCNTs) composites. The ultrasonic mixing technique was applied to disperse the MWCNTs material into polyethylene terephthalate. The intensities of absorption of hydroxyl and carbonyl group decreased with increasing the addition of MWCNTs from (0.1-1%), comparing with pure PET. The results of TGA showed that the incorporation of MWCNTs into pure PET slightly improves the thermal stability because interfaces between multifuntionlized MWCNTs and pure PET causes of reducing brittle behavior and increased due to the high crosslinking of pure PET. The mechanical tests appeared significant improvements with increasing of MWCNTs concentrations. The SEM micrographs showed more voids between the pure PET chains before adding MWCNTs while MWCNTs-PET composites appeared more homogeneous, crosslink density and less voids between the chains.

Effect of different mixing methods on the physical properties of Portland cement.

BackgroundThe Portland cement is hydrophilic cement; as a result, the powder-to-liquid ratio affects the properties of the final mix. In addition, the mixing technique affects hydration. The aim of this study was to evaluate the effect of different mixing techniques (conventional, amalgamator and ultrasonic) on some selective physical properties of Portland cement.Material and MethodsThe physical properties to be evaluated were determined using the ISO 6786:2001 specification. One hundred sixty two samples of Portland cement were prepared for three mixing techniques for each physical property (each 6 samples). Data were analyzed using descriptive statistics, one-way ANOVA and post hoc Tukey tests. Statistical significance was set at P<0.05.ResultsThe mixing technique had no significant effect on the compressive strength, film thickness and flow of Portland cement (P>0.05). Dimensional changes (shrinkage), solubility and pH increased significantly by amalgamator and ultrasonic mixing techniques (P<0.05). The ultrasonic technique significantly decreased working time, and the amalgamator and ultrasonic techniques significantly decreased the setting time (P<0.05).ConclusionsThe mixing technique exerted no significant effect on the flow, film thickness and compressive strength of Portland cement samples. Key words:Physical properties, Portland cement, mixing methods.

Development of a lead-free composite solder from Sn–Ag–Cu and Ag-coated carbon nanotubes

The microelectronic applications of lead-free solders pose ever-increasing demands. We seek to improve the solder by forming composites with Ag-coated single-walled carbon nanotubes (Ag-coated SWCNTs). These were incorporated into 96.5Sn–3.0Ag–0.5Cu solder alloy with an ultrasonic mixing technique. Composite solder pastes with 0.01–0.10 wt% nanotube reinforcement were prepared. The wettability, melting temperature, microstructure and mechanical properties of the composite solders were determined, and their dependency on nanotube loading assessed. Loading with 0.01 wt% Ag-coated SWCNTs improved the composite solder’s wetting properties, and the contact angle was reduced by 45.5 %, while over loading of the coated nanotubes up to 0.10 wt% degraded the wettability. DSC results showed only slight effects on the melting behavior of the composite solders. Cross-section microstructure analysis of the spreading specimens revealed uniform distribution of the intermetallic compounds throughout the solder matrix, and EDS analysis identified the phases as β-Sn, Ag3Sn and Cu6Sn5. The mechanical properties of composite specimens, compared with those of unloaded 96.5Sn–3.0Ag–0.5Cu solder, had a maximal improvement in the shear strength of 11 % when the nanotube loading was 0.01 wt% of Ag-coated SWCNTs.

Nucleation Catalysis in Aluminum Alloy A356 Using Nanoscale Inoculants

Different types of nanoparticles in aluminum (Al) alloy A356 nanocomposites were shown to catalyze nucleation of the primary Al phase. Nanoparticles of SiC β, TiC, Al2O3 α, and Al2O3 γ were added to and dispersed in the A356 matrix as nucleation catalysts using an ultrasonic mixing technique. Using the droplet emulsion technique (DET), undercoolings in the nanocomposites were shown to be significantly reduced compared to the reference A356. None of the nanocomposites had a population of highly undercooled droplets that were observed in the reference samples. Also, with the exception of the A356/Al2O3 α nanocomposite, all nanocomposites showed a reduction in undercooling necessary for the onset of primary Al nucleation. The observed nanocomposite undercoolings generally agreed with the undercooling necessary for free growth. The atomic structure of the particles showed an influence on nucleation potency as A356/Al2O3 γ nanocomposites had smaller undercoolings than A356/Al2O3 α nanocomposites. The nucleation catalysis illustrates the feasibility of, and basis for, grain refinement in metal matrix nanocomposites (MMNCs).

Study on synergistic effect of ordered mesoporous carbon and carbon aerogel during electrochemical charge–discharge process

Ordered mesoporous carbon/carbon aerogel (OMC/CA) composites have been obtained by a simple ultrasonic mixing technique. It is found that there exists a synergistic effect between OMC’s channel-like mesopores and CA’s network-like mesopores during electrochemical charge–discharge process; and the maximum synergistic coefficient arrives at 0.37 when CA content is 30 wt.%. As a result, the as-prepared OMC/CA composites can make full use of the two-dimensional order of mesoporous structure of OMC and the three-dimensional connectivity of mesoporous structure of CA, and thus, exhibit much better electrochemical properties as compared to OMC and CA alone.

高分子テンプレート法を用いた新規球状ＢＳＴ粒子合成法の検討

Synthesis of BST (Ba0.5Sr0.5TiO3) spherical particles by polymer templating method was investigated. N-Vinylpyrrolidone-co-styrene polymer was used for polymer templates. Macromolecular metal-complex of Ba, Sr and Ti was selected as BST precursor. BST precursor was introduced to the polymer templates by an ultrasonic mixing technique. Templates filled with BST precursor were heated at 600, 700, 800, and 900°C in the air. Crystalline phase, particle size and morphology of BST particles were characterized by FE-SEM and XRD. FE-SEM and XRD analysis showed the formation of spherical particles composed of Ba0.5Sr0.5TiO3 crystalline in cubic phase. When BST precursor was heated without templates, BST particles were irregular in shape.By using this method, spherical BST particles having lower crystallization temperature and higher homogeneity in composition were successfully synthesized in a simple process.