Ultrasonic Cavitation Technique Research Articles

Influence of boron carbide and graphite particulates on the microstructural and mechanical properties of Al6061 metal matrix

Al6061 metal matrix composites were fabricated via the Stir casting method with ultrasonic cavitation technique for various weight percentage of Boron carbide and Graphite particulates as reinforcements (Al6061-0.5wt.%Gr-(0.6, 1.2, 1.8wt.% B4C). The microstructural and mechanical behavior of the fabricated Hybrid composites were studied. The Hardness of the composites was measured by two metrics: Brinell and Micro-Vickers. Density and Porosity of the composites were determined based on their hardness values. Mechanical properties, including uniaxial tensile, flexural, and compression strengths, were assessed using a Universal Testing Machine. The homogeneous distribution of Graphite and Boron Carbide particles in the Al6061-0.5wt%Gr-1.2wt%B4C composite specimen were confirmed through a Field Emission Scanning Electron Microscope (FESEM) and Energy Dispersive Spectroscopy (EDS) analysis. Additionally, interfacial analysis of the metal matrix composite was performed using X-ray diffraction (XRD). The specific uniaxial tensile, flexural and compression properties of Al6061-0.5wt%Gr-1.2wt%B4C increased by 15.63%, 51.27%, and 47.59% respectively. The specific hardness of Brinell and Micro-Vickers of the composite increased by 51.44% and 45.04% respectively. Additionally, the composite exhibited an impact energy of 16 J.

Investigations on Mechanical Properties of Nano Particulates (Al<sub>2</sub>O<sub>3</sub>/B<sub>4</sub>C) Reinforced in Aluminium 7075 Matrix Composite

Metal Matrix Nano Composites (MMNCs) with the addition of nano-particulate reinforcements can be of significance for automobile, aerospace, and numerous applications due to their low density and good mechanical properties, better corrosion and wear resistance, low coefficient of thermal expansion as compared to conventional materials. Designing the metal matrix composite material aims to combine the desirable attributes of metals and ceramics. The present work is focused on studying the mechanical properties of aluminium alloy (7075) with Al2O3 and B4C nanocomposite produced using the stir casting technique and ultrasonic cavitation method. Different % age of reinforcement is used. An ultrasonic cavitation technique is used to achieve a uniform dispersion of nano-particulate Al2O3 and B4C in molten aluminium alloy. Tensile, Hardness, and Impact tests were performed on the samples obtained by the fabrication processes. A structural study will be carried out through a Scanning Electron Microscope (SEM) to know the distribution of Al2O3/B4C Nano particulates in Al alloy.

Ultrasonication induced synthesis of TPGS stabilized clove oil nanoemulsions and their synergistic effect against breast cancer cells and harmful bacteria

The present work reports the fabrication of TPGS assisted clove oil in water nanoemulsion for the delivery of polyphenolic nutraceuticals i.e. curcumin and resveratrol and the analysis of their synergetic healing potential. The fabrication procedure was undertaken by the use of high energy ultrasonic cavitation technique. The morphological and rheological properties of the fabricated systems were analyzed and optimized using numerous techniques. The current study throws light on the influence of surfactant type and composition on the mixing stability of oil phase. Both curcumin and resveratrol were effectively loaded in the nanoemulsion, and their loading efficiencies were found to be 99.87 and 99.38%, respectively. The study was undertaken with the aim of exploring the versatile therapeutic potential by elevating the established antimicrobial activity of curcumin and resveratrol and testing their prospects against breast cancer cell lines. The results demonstrated the antimicrobial activity of nanoemulsion (without nutraceuticals) itself against gram-positive and gram-negative bacteria owing to the clove oil which would be an asset in accomplishing better results. In combination with curcumin and resveratrol, it exhibited enhanced effect against different bacterial strains thus showcasing an increase in its efficacy. Furthermore, the anti-tumor activity of prepared formulations has been tested on MDA MB −231 and Hep G2 breast cancer cell lines to broaden the horizons of biological applications of the formulated system.

Low-frequency ultrasound assisted synthesis of an aqueous aluminium hydroxide decorated graphitic carbon nitride nanowires based hybrid nanofluid for the photocatalytic H2 production from Methylene blue dye

An aqueous Aluminium Hydroxide [Al(OH)3] decorated Graphitic Carbon Nitride [g-C3N4] nanowires based hybrid nanofluid has been fabricated using the two-step method. Where, both the nanoparticles are synthesized separately and dispersed throughout the base fluid with the aid of ultrasonic cavitation technique. The hybrid nanofluid photocatalytic performance has been compared with Al(OH)3 – (g-C3N4) hybrid photocatalyst. After the preparation, the hybrid nanofluid and nanoparticles properties are systematically characterized. The FESEM results confirmed the effectiveness of the low frequency (30 kHz) ultrasonication in coating the Al(OH)3 nanoparticle on to the g-C3N4 surface. The larger BET specific surface area (80.45 m2/g) and the lower bandgap energy (2.35 eV) assured the enhanced photocatalytic H2 production from the degradation of Methylene Blue dye. Moreover, the obtained 0.5 vol% Al(OH)3–(g-C3N4)/H2O hybrid nanofluid produced about 6 times higher H2 than that of Al(OH)3 – (g-C3N4) hybrid photocatalyst. Even after 4 cycles, the hybrid nanofluid showed only 1% decrement in the photocatalytic performance. This study of replacing photocatalyst with the hybrid nanofluid delivers a sustainable route to harvest the H2 from photocatalytic degradation of the industrial pollutants in the presence of visible light.

Mechanical and corrosion characteristics of grain refined ZA-27 alloy and ZA-27/Al2O3 nano-composite produced by ultrasonic cavitation technique

Mechanical and corrosion characteristics of grain refined ZA-27 alloy and ZA-27/Al2O3 nano-composite produced by ultrasonic cavitation technique

Mechanical and Wear Properties of Aluminum-Based Nanocomposites Fabricated through Ultrasonic Assisted Stir Casting

Abstract The aluminum alloy AA6061 with 0.004, 0.008, 0.012, and 0.016 volume fractions of silicon carbide (SiCp) nanocomposites were fabricated using a semi-solid stirring assisted ultrasonic cavitation technique. Specimens are tested for morphology, density, mechanical, and wear properties. The density, strength, and microhardness of the nanocomposites increased with the increase of SiCp nano-reinforcement particles in the matrix. The yield strength of the SiCp-reinforced nanocomposites was evaluated by considering various strengthening mechanisms. It is found that the yield strength of the nanocomposites increased by 96 % for 0.004, 172 % for 0.008, 158 % for 0.012, and 206 % for 0.016 volume fractions of SiCp compared to the base alloy. The dislocation mismatch effect and Orowan strengthening effect are found to play a significant role in the SiCp-reinforced AA6061 nanocomposites. The dislocation mismatch effect increased with the reinforcement particles’ size reduction in the matrix. The Orowan strengthening effect increased up to 1.56 nm critical size of SiCp, and above that it decreased slightly. The experimental results are compared to predicted results obtained from various analytical models. The experimental results are observed to be in close agreement with the Mirza and Chen model. The wear loss of nanocomposites decreased with an increase in the nano-sized SiCp reinforcement quantity in the matrix. The amount of 0.004, 0.008, 0.012, and 0.016 volume fractions of nano-sized SiCp reinforcement additions to the AA6061 alloy matrix decreases the wear coefficient by 19.23 %, 38.46 %, 57.69 %, and 62.69 %, respectively. The worn surfaces were also analyzed using a scanning electron microscope and energy-dispersive X-rays.

Performance and Emission Studies of a Variable Compression Ratio CI Engine using Bio Diesel Made from Waste Cooking Oil

Compression ignition (CI) engine is the un-debated choice for power applications, stationary or mobile. There is an urgent need of alternative high potential fuel for CI engines in order to fulfill energy needs without hampering the thermal performance and stringent emission standards. Here waste cooking oil is chosen as an alternative fuel, which is upgraded into biodiesel in the laboratory using mechanical stirring and ultrasonic cavitation technique of biodiesel production. Four blends of cooking oil are made by increasing 20% its amount in conventional diesel fuel. Performance is analyzed for two compression ratios, 15 and 17.5, on the existing VCR diesel engine set up interfaced with “Engine Soft” software. The results show that as bio-diesel concentration in a blend increases, the thermal performance (i.e., brake thermal efficiency) and emissions (i.e., CO, HC and NOx, and smoke intensity) are observed to be marginally higher; on the other hand, as compression ratio increases, the thermal performance improves; CO and smoke opacity decreases.

Harnessing cavitational effects for green process intensification

The impressive chemico-physical effects observed in sonochemistry are a result of cavitation, as ultrasonic and hydrodynamic cavitation does not interact with matter at the atomic and molecular levels. Bubble collapse leads to the quasi-adiabatic heating of the vapour inside bubbles, giving rise to local hot spots in the fluid. Cavitation thus transforms a mechanical energy into high kinetic energy, which is released in very short bursts that are exploited for green process intensification. This paper reviews relevant applications of hydrodynamic and acoustic cavitation with the aim of highlighting the particular advantages that these phenomena offer to the intensification of green chemical processes. Emulsification, biodiesel preparation, wastewater decontamination, organic synthesis, enzymatic catalysis and extractions are discussed among others. As a comparison, hydrodynamic cavitation technique is more advantageous in dealing with process intensification at large-scale, as well as the enhancement of mass transfer and heat transfer, while ultrasonic cavitation technique is more convenient to operate, easier to control in the studies at lab-scale, and exhibits more efficient in producing active free radicals and inducing the cleavage of volatile compounds.

Pressurized ultrasonic production of biodiesel from Jatropha oil: optimization and energy analysis

ABSTRACTThe present study deals with the development of a biodiesel production reactor based on pressurized ultrasonic cavitation technique. Transesterification of Jatropha oil takes place by passing low-frequency ultrasonic irradiation in the reaction mixture flowing at pressurized conditions in the sonochemical reactor. Reaction variables such as reaction time, molar ratio, catalyst concentration, and pressure of the reaction mixture were investigated to find the optimal parameters for biodiesel production. The energy requirement decreases with increase in pressure. Very low value of Specific Energy Consumption (0.018 kWh/kg) and significantly high value of Energy Use Index (598.83) are obtained when the pressure of reaction mixture is 15 bar. Increasing the pressure thereafter, leads to nominal gains. Ultrasonic irradiation at high-pressure condition has an additional advantage of rapid reaction and lower requirement of alcohol to oil molar ratio and catalyst concentration. Fifteen bar pressure is optimal for biodiesel production.

Tensile Behavior of SiCNP and MWCNTs Filled Toughened Epoxy Nanocomposites: A Comparative Study

This study is conducted to evaluate the tensile properties of silicon carbide nanoparticles (SiCNP) and multiwalled carbon nanotubes (MWCNTs) filled toughened epoxy composites as a function of filler loading. The nanocomposites with different weight percentage of SiCNP and MWCNTs loading were fabricated by mechanical blending operation assisted with an ultrasonic cavitation technique. The loadings utilized were 0, 2, 4, and 6% of total composites weight. The result shows that the optimum filler loading of both systems were obtainable at 4% of SiCNP and MWCNTs of loadings. Composite with SiCNP filler achieved the highest value of tensile strength and Young's modulus at about 11% and 4%, respectively as compared to unfilled system. The enhancement pattern in MWCNTs nanocomposite systems were not significant as compared than SiCNP composite. The tensile strength and Young's modulus of MWCNTs composite were increased at only about 7% and 2%, respectively compared than unfilled system. The strain at break attribute for both filler system had shown reduction pattern at higher loading started from 2% loading and onwards. The variation in tensile properties were further supported by the tensile fracture morphologies and clearly shown that the filler-matrix plated an important role in affecting the tensile behavior of nanocomposite produced.

Polypropylene/nTiO2 nanocomposites using melt mixing and its investigation on mechanical and thermal properties

This study investigates the preparation of nTiO2 particle using green chemistry approach and its subsequent effect on the properties of isotactic polypropylene (iPP) nanocomposites, which is one of the most suited thermoplastic polymer. The nanocomposite of iPP with TiO2 nanoparticle (0.5, 1, 1.5, 2, and 2.5 wt%) were prepared on Brabender plasticorder, which was then subjected to injection molding to get a dumbbell‐shape specimens. Meanwhile, TiO2 nanoparticles (nTiO2) were prepared using ultrasonic cavitation technique using leaf extract of Murraya koenigii. The extraction of leaf was carried out using distilled water as a solvent. The size and shape of nTiO2 particle was confirmed using transmission electron microscope and found to be spherical shape of diameter ∼10–45 nm. The mechanical properties of nTiO2 reinforced iPP composites were studied using universal testing machine. Moreover, thermal properties were studied using Vicat softening temperature, thermogravimetric analyzer, and differential scanning calorimeter. The extent of dispersion of nTiO2 in iPP matrix was studied using field‐emission scanning electron microscope and X‐ray diffractometer. The mechanical and thermal properties of nTiO2‐iPP composites were found to be improved significantly with increasing amount of nTiO2 particles except elongation at break, which is a marginal increment. This improvement in properties (mechanical and thermal) was due to the uniform dispersion of nTiO2 in iPP matrix, which means that chains of polymers were well adhered with the spherical shaper particles. POLYM. COMPOS., 38:1273–1279, 2017. © 2015 Society of Plastics Engineers

Ultrasonic Attenuation Based Inspection Method for Scale-up Production of A206–Al2O3 Metal Matrix Nanocomposites

A206–Al2O3 metal matrix nanocomposite (MMNC) is a promising high performance material with potential applications in various industries, such as automotive, aerospace, and defense. Al2O3 nanoparticles dispersed into molten Al using ultrasonic cavitation technique can enhance the nucleation of primary Al phase to reduce its grain size and modify the secondary intermetallic phases. To enable a scale-up production, an effective yet easy-to-implement quality inspection technique is needed to effectively evaluate the resultant microstructure of the MMNCs. At present the standard inspection technique is based on the microscopic images, which are costly and time-consuming to obtain. This paper investigates the relationship between the ultrasonic attenuation and the microstructures of pure A206 and Al2O3 reinforced MMNCs with/without ultrasonic dispersion. A hypothesis test based on an estimated attenuation variance was developed and it could accurately differentiate poor samples from good ones. This study provides useful guidelines to establish a new quality inspection technique for A206–Al2O3 nanocomposites using ultrasonic nondestructive testing method.

Effect of nBaCO3 on mechanical, thermal and morphological properties of isotactic PP-EPDM blend

Isotactic polypropylene (iPP): ethylene propylene diene monomer (EPDM) blend is one of the most suited compatible and miscible blends. The blends of iPP and EPDM (80:20) filled with BaCO3 nanoparticles (0.5, 1.5, 2.5 and 3 wt%) were prepared on Brabender Plasticorder, which was then subjected to injection molding to get dumbbell-shaped specimens. Meanwhile, BaCO3 nanoparticles (nBaCO3) were prepared using ultrasonic cavitation technique. The size and shape of nBaCO3 particle was confirmed using transmission electron microscope and found to be capsule shape of diameter ~40–60 nm with aspect ratio (l/d) of 2.2–2.5. The reduction in particle size of nBaCO3 leads to formation of uniform suspension. The solution was kept as such for long time so as to nullify the charges developed over the surface of nanoparticles. The mechanical properties of nBaCO3-reinforced iPP-EPDM blends were studied using universal testing machine and impact tester. Moreover, thermal properties were studied using flammability tester, vicat softening temperature, thermo gravimetric analyzer and differential scanning calorimeter (DSC). Dispersion of nBaCO3 in iPP-EPDM matrix was studied using scanning electron microscope and X-ray diffractometer. The mechanical and thermal properties of iPP-EPDM/nBaCO3 blends were found to be improved significantly with increasing amount of nBaCO3 up to 2.5 wt%, which is due to good compatibility in between iPP and EPDM with uniform dispersion of nBaCO3. Moreover, due to agglomeration at 3 wt% loading of nBaCO3 few of the properties found to be decreased marginally.

Effect of nAl(OH)3 on thermal, mechanical and morphological properties of millable polyurethane (MPU) rubber

Aluminium hydroxide nanoparticles [nAl(OH)3] were synthesized using continuous ultrasonic cavitation technique. The size and shape of synthesized nanoparticles were confirmed using X-ray diffraction and transmission electron microscopy, which was found to be ~55 nm in diameter with needle shape. Millable polyurethane (MPU) rubber nanocomposites were prepared with nAl(OH)3 as a filler (0.5–2.5 wt% loading) using two-roll mill and moulded on compression moulding machine. Dicumyl peroxide was used as a curing agent. Mechanical property and abrasion resistance was determined using universal testing machine (UTM) and abrasion resistance tester, respectively. Physical (hardness and swelling index) and thermal (flammability and stability) properties were also studied on shore A hardness tester, flammability tester and thermo gravimetric analyzer, respectively. The extent of dispersion of nAl(OH)3 in MPU matrix was studied using scanning electron microscope (SEM) and atomic force microscope (AFM). MPU rubber:nAl(OH)3 nanocomposites show improved mechanical, physical and thermal properties compared to pristine MPU composite. This dramatic improvement in properties was due to very small grain size of nAl(OH)3, which facilitates uniform dispersion of nanoparticles within the chains of MPU rubber. This improvement in properties were up to 2 wt% and decreases subsequently (2.5 wt%) due to agglomeration. nAl(OH)3 behaves like an ordinary filler at higher wt% loading.

Effect of Mg(OH)2 nanoparticles on thermal, mechanical and morphological properties of millable polyurethane elastomer

Millable polyurethane (MPU) rubber nanocomposites were prepared on a two-roll mill and molded on a compression molding machine. The amount of loading of Mg(OH)2 nanoparticles ( nMg(OH)2) was from 0.5 to 2.5 wt% followed by the addition of dicumyl peroxide (as a curing agent). The compounded matter was subjected to compression molding so as to get a cure sheet (130 × 130 × 3 mm). Mechanical (tensile strength, elongation at break (%) and abrasion resistance index), physical (hardness and swelling index), and thermal properties (flammability retardency and degradation stability) were studied. The extent of dispersion of nMg(OH)2 particles was studied using scanning electron microscope and atomic force microscope. nMg(OH)2 was synthesized using continuous ultrasonic cavitation technique. The size and shape of nMg(OH)2 was confirmed using X-ray diffraction and transmission electron microscopy, which was found to be ∼20–60 nm with quasi shape. MPU:nMg(OH)2 nanocomposites show improved mechanical, physical, and thermal properties compared to pristine MPU. This improvement was due to very fine grain size of nMg(OH)2, which facilitates uniform dispersion of nMg(OH)2 within MPU rubber matrix. However, higher loading of nMg(OH)2 shows marginal decrement in properties due to agglomeration, especially at 2.5 wt%.

Biodegradation of polystyrene (PS)-poly(lactic acid) (PLA) nanocomposites using Pseudomonas aeruginosa

Poly(lactic acid) (PLA) was synthesized using condensation polymerization of L-lactic acid using a controlled ultrasonic cavitation technique. Polystyrene (PS) was used to prepare the PS:PLA and PS:PLA:organically modified montmorillonite (OMMT) composites. PS was dissolved in benzene (10:90) and kept overnight for dissolution. Meanwhile, surface modification of montmorillonite was done using a column chromatography technique and referred to as OMMT. The d-spacing was found to be 22 A after modification due to sufficient column length and diameter with good retention time during ion exchange. PLA and OMMT were kept in hot air oven at 100 oC for 30 min to remove the moisture. The mixtures of 10%, 15%, 20%, 25%, and 30% of PS:PLA:OMMT were subjected to ultrasonic irradiation (50 Hz) for homogenization and to form a biodegradable polymer nanocomposite sheet (5 × 5 cm2). The amount of OMMT loading was from 0.5–5 mass%. These composites were subjected to degradation in minimal medium using Pseudomonas aeruginosa bacteria at controlled conditions, and the polymer is a major source of carbon. The degradation was confirmed using scanning electron microscopy, extracellular protein content change, biomass production, and % degradation with respect to time (up to 28 days) after incubation. Open image in new window

High Strain Rate Response of Sandwich Composites with Nanophased Cores

Polyurethane foam materials have been used as core materials in a sandwich construction with S2-Glass/SC-15 facings. The foam material has been manufactured from liquid polymer precursors of polyurethane. The precursors are made of two components; part-A (diphenylmethane diisocyanate) and part-B (polyol). In one set of experiments, part-A was mixed with part-B to manufacture the foam. In another set, TiO2 nanoparticles have been dispersed in part-A through ultrasonic cavitation technique. The loading of nanoparticles was 3% by weight of the total polymer precursor. The TiO2 nanoparticles were spherical in shape, and were about 29 nm in diameter. Sonic cavitation was carried out with a vibrasound liquid processor at 20 kHz frequency with a power intensity of about 100 kW/m2. The two categories of foams manufactured in this manner were termed as neat and nanophased. Sandwich composites were then fabricated using these two categories of core materials using a co-injection resin transfer molding (CIRTM) technique. Test samples extracted from the panel were subjected to quasi-static as well as high strain rate loadings. Rate of loading varied from 0.002 s−1 to around 1300 s−1. It has been observed that infusion of nanoparticles had a direct correlation with the cell geometry. The cell dimensions increased by about 46% with particle infusion suggesting that nanoparticles might have worked as catalysts during the foaming process. Correspondingly, enhancement in thermal properties was also noticed especially in the TGA experiments. There was also a significant improvement in mechanical properties due to nanoparticle infusion. Average increase in sandwich strength and energy absorption with nanophased cores was between 40–60% over their neat counterparts. Details of manufacturing and analyses of thermal and mechanical tests are presented in this paper.

Microbubble Spectra and Superheat in Water and Sodium, Including Effect of Fast Neutron Irradiation

The microbubble spectrum in a sample of tap water was measured by the Coulter counter technique under various conditions, and at the same time the tensile strength (i.e., “superheat” capacity) of the tap water was measured by the ultrasonic cavitation technique. It was observed in this experiment that the microbubble population and size increased and the superheat decreased for increasing temperature and under fast neutron irradiation. Finally the generalized Noltingk-Neppiras equation was solved numerically for selected initial microbubble radii, and the suppression pressure (or superheat) determined by this numerical solution was compared with the experimental result. Apparent inconsistencies in experimental results may be primarily due to the neglect of the rectified diffusion effect in the present analysis.