Ultrasonic Cavitation Process Research Articles

A study on reducing hydrogen content in steel using ultrasonic cavitation process

In this study, a novel process utilizing ultrasonic cavitation(UC) was proposed to decrease hydrogen content in steel. Electrochemical hydrogen-charging and UC were performed on steels with different elemental species and ratios, and hydrogen embrittlement(HE) susceptibility was evaluated by slow strain rate tensile(SSRT). UC effectively reduced hydrogen-induced plasticity loss by removing hydrogen trapped by traps, particularly in SA508Gr.3. Dehydrogenation effects and recovery mechanisms were explored. Hydrogen trapped by low-energy traps played a critical role in hydrogen-induced hardening. The cleavage platforms of the specimen after UC was reduced, but a large number of microcracks appeared in the fracture due to residual hydrogen.

Ultrasonic cavitation processing of multi-functional materials

Ultrasonic cavitation processing (USP) is a versatile technique that has gained a lot of momentum in the last decade as a sustainable, environmentally friendly, and cost-effective process. USP uses high-frequency sound to form bubbles that expand, contract, and eventually collapse, generating high-speed liquid jets, powerful shockwaves, and acoustic streaming effects. Despite its widespread application, use of USP remains mostly empirical. For processes involving the synthesis and production of materials, harnessing the power of cavitation requires an understanding of the fundamental mechanisms driving USP. In this presentation, we record recent studies to analyse, optimise, and control USP for applications related to grain refinement of aluminium alloys, exfoliation of 2D nanomaterials, and processing of composites. High-speed cameras and in situ synchrotron imaging were used to visualise cavitation dynamics, coupled with state-of-the-art hydrophones to detect acoustic waves and shockwave emissions. Results show that optimised USP with the help of advanced modelling significantly improves grain refinement of aluminium alloys in processes such as direct-chill (DC) casting, where shockwaves are primarily responsible for the fragmentation of intermetallic crystals/dendrites. Furthermore, shockwaves act as the main driving mechanism for the exfoliation of 2Ds while cavitation activity enhances fibre dispersion in highly viscous polymers, improving matrix stability and strength.

Optical, rheological, dielectric, and electrical properties of multiple oxides nanosuspended glycerol based semiconductor hybrid nanofluids

Semiconductor hybrid nanofluids (SHNFs) of multiple hybrid nano oxides (TiO2 + ZnO, TiO2 + Al2O3, TiO2 + SiO2, ZnO + Al2O3, and ZnO + SiO2) dispersed at fixed concentration (0.01 wt/wt%) in glycerol (Gly) fluid were prepared through solution mixing and probe ultrasonic cavitation process. These formulated SHNFs (i.e., TiO2 + ZnO/Gly, TiO2 + Al2O3/Gly, TiO2 + SiO2/Gly, ZnO + Al2O3/Gly, and ZnO + SiO2/Gly) were characterized by employing an ultraviolet–visible (UV–vis) spectrophotometer (wavelength range 200 – 800 nm), rheometer (shear rate range 1.32 – 5.28 s−1), and precision inductance–capacitance–resistance (LCR) meter (frequency range 50 Hz – 1 MHz). The dependency of UV–vis absorbance on the equal weight amount combinations of semiconductive and insulating nanosuspended hybrid oxides for these SHNFs was explored and analyzed for energy band gaps which showed strongly ruled by the wide band gap semiconductor TiO2 and ZnO materials. Dielectric permittivity, electrical conductivity, impedance, and electric modulus spectra of these SHNF materials were reported at 298.15 K and confirmed the influence of nanosuspended hybrids on the dielectric polarizations and relaxation behaviour. Dynamic viscosity and shear stress study with the shear rate explained the Newtonian behaviour of these SHNF materials. The multi-functionality of these novel SHNFs for the advances in soft condensed matter device/system technologies including optoelectronic, photovoltaic, UV-blocking, sensing, wavelength filtering, nanodielectric, electrical insulator, and thermal energy and mass transporter were demonstrated.

Multiphysics of multifunctional nanofluids based on different oxides nanoparticles and glycerol fluid

Nanofluid (NF) materials consisting of glycerol (Gly) and different inorganic nano oxides (TiO2, ZnO, Al2O3, and SiO2 for the oxides concentration of 0.01 wt% to the weight of Gly base fluid) were prepared by a two-step method through ultrasonic cavitation process. These nanofluids were investigated by employing an X-ray diffractometer (XRD), ultraviolet–visible (UV–Vis) spectrophotometer, 20 Hz to 1 MHz frequency range dielectric relaxation spectroscopy (DRS), ultrasonic interferometer, and rotational viscometer. The multiphysics of these nanofluids includes structural and optical properties, dielectric permittivity, electrical conductivity, conductivity relaxation, ultrasound velocity, adiabatic compressibility, acoustic impedance, viscosity, density, thermal conductivity, and viscoacoustic relaxation were characterized. The XRD patterns identified monodispersed and stable suspensions of these different characteristic nanoparticles in the hydrogen-bonded 3D supramolecular structure of ultra-high viscous glycerol fluid which were supported by their UV–Vis absorbance analyses. The energy band gap values of the TiO2 and ZnO containing nanofluids were found primarily ruled by the characteristic optical properties of these oxides nanomaterials. The complex dielectric and various electrical functions studied at 25 °C revealed that the suspension of different oxide nanoparticles in the glycerol fluid increased the static permittivity whereas reduced the direct current electrical conductivity which showed strong conductivity relaxation process dependence. The rheological measurements of the formulated nanofluids were performed over a shear rate range of 0.4–40 s−1 at temperatures of 25–55 °C. The linear relationship between shear rate and shear stress and also the shear rate-independent viscosity revealed the Newtonian behaviour of these nanofluids. The shear viscosity non-linearly decreased with the increase of temperature and exhibited the Arrhenius behaviour for all different oxides containing Gly-based nanofluids. The acoustic parameters of the nanofluids were altered unevenly with types of nano oxides and inferred some structure-property correlations. The promising technologically useable properties of these nanofluids were expected to impact their potential applications in optoelectronics, UV-blocking, sensing, nanodielectrics, energy storing and electric insulation, heat transfer systems, and also in materials processing for the development of innovative soft condensed devices.

Study on the Motion Characteristics of Solid Particles in Fine Flow Channels by Ultrasonic Cavitation.

Microjets caused by the cavitation effect in microchannels can affect the motion trajectory of solid particles in microchannels under ultrasonic conditions. The optimal parameters for an observation experiment were obtained through simulations, and an experiment was designed to verify these parameters. When the cavitation bubbles collapse in the near-wall area, the solid particles in the microchannel can be displaced along the expected motion trajectory. Using fluent software to simulate the bubble collapse process, it can be seen that, when an ultrasonic sound pressure acts on a bubble near the wall, the pressure causes the top of the bubble wall to sink inward and eventually penetrate the bottom of the bubble wall, forming a high-speed microjet. The maximum speed of the jet can reach nearly 28 m/s, and the liquid near the top of the bubble also moves at a high speed, driving the particles in the liquid towards the wall. A high-speed camera was used to observe the ultrasonic cavitation process of bubbles in the water to verify the simulation results. A comparison of particle motion with and without ultrasonic waves proved the feasibility of using the ultrasonic cavitation effect to guide small particles towards the wall. This method provides a novel experimental basis for changing the fluid layer state in the microchannel and improving precision machining.

Comprehensive environmental assessment of innovative humic agro product

There has been made the assessment of the product «CAVITA BIOCOMPLEX» quality parameters, manufactured according to the innovative technology of ultrasonic cavitation processing of peat in water medium at high static pressure. To carry out this assessment it has been used the universal system of procedure of comprehensive assessment of humic products. This system is based on the level approach. It was found that the sample of agro product in the capacity of the main bioactive components contains fulvic and humic acids (47.2-64.0% calculated at dry weight basis). It is chemically and biologically safe for the environment. The usage of high-quality natural raw materials in combination with the “green” technology of “CAVITA BIOCOMPLEX” production makes it possible to use it not only as additional application with any mineral or organic fertilizers, plant protection products, herbicides, but also as basic fertilizer for biological agricultural technologies.

Techno-economic assessment of biodiesel production from canola oil through ultrasonic cavitation

The immiscibility of oil and alcohol is a severe issue in biodiesel production as it causes a low mass transfer rate and long reaction time. This problem can be overcome by incorporating the intensification method, which significantly increases the contact surface area of oil and alcohol through various techniques. In recent years, ultrasonic cavitation has emerged as one of the most effective ways for this purpose. However, it is still unclear whether this technology will provide the industry with an economically profitable process. This paper attempts to assess the potential of ultrasonic cavitation from a techno-economic viewpoint. Two plants based on the conventional mechanical stirring and ultrasonic cavitation processes were designed using Aspen HYSYS V8.4. Total investment, costs of products, net present value, and internal rate of return were used to compare the two processes together. The total investment in the ultrasonic cavitation process was lower than that of the mechanical stirring process by approximately 20.8%. Compared to the conventional process, using ultrasonic reactors also caused products’ costs to reduce by 5.2%. Owing to a positive net present value and an internal rate of return of 18.3%, the ultrasonic cavitation process was a better choice. Moreover, ultrasonic cavitation resulted in a meaningful decrease in both consumed energy and the production of wastes. The overall energy consumption was reduced by 6.9% when ultrasonic cavitation was employed. The amount of waste produced in the ultrasound-assisted process was one-fifth of that in the mechanical stirring process.

Experimental Investigation of Peening Cylindrical Workpieces Utilizing a Transducer with Ring Sonotrode

In industrial applications, the shafting components with high stress are easily damaged due to cyclic loads if there is no surface treatment. With the use of ultrasonic cavitation peening, the residual compressive stress and the surface hardness of these components can be improved. While traditional longitudinal vibration transducers are used to treat cylindrical workpieces, the treated areas are limited, and the treatment period is relatively long. To solve these problems, we designed a novel configuration of the piezoelectric transducer as a type of the combination of rod and ring. During ultrasonic cavitation peening, we placed the cylindrical workpieces in the ring tool to improve the limitation. However, the treated surface properties were largely influenced by the input parameters (driving voltage and rod diameters). In this investigation, the cylindrical workpieces, which were covered with aluminum foils, were first treated by ultrasonic cavitation peening to detect the intensity and distribution of the cavitation bubbles on the treated surface. Then, the sonochemiluminescence method was utilized as an additional way to find the optimal operation parameters (190 V and 16 mm). Finally, the ultrasonic cavitation process was conducted with the optimal parameters. The treatment results showed that the surface hardness increased by about 36% without significant increase of the surface roughness.

Ultrasound-Assisted Through-Mask Electrochemical Machining of Hole Arrays in ODS Superalloy.

Micro-hole arrays have found wide applications in aerospace, precision instruments, and biomedicine. Among various methods of their production, including mechanical, laser, and electrical discharge, electrochemical machining (ECM) is considered the most lucrative due to its wide processing range, high surface quality, and excellent productivity. In particular, ultrasound-assisted through-mask ECM exhibits an enhanced machining precision due to ultrasonic cavitation, which promotes the removal of the electrolytic products and bubbles. In this study, the equation of cavitation bubble oscillation was derived and numerically solved to study the influence of six different parameters on the ultrasonic cavitation and electrolysis process, and their optimal values were determined. The feasibility of the proposed ultrasound-assisted through-mask ECM technology with the optimized parameters was experimentally corroborated by the fabrication of a high-quality hole array in an oxide dispersion strengthened (ODS) MA956 superalloy.

Estimation of efficiency of ultrasonic cavitation processing of technological media on energy criteria

The paper presents the energy evaluation of cavitation treatment of technological environments with the aim of establishing such parameters that implement the optimal conditions to maximize the transfer of energy to the stages in cavitation generation, development and slam shut bubbles. Accounting multiple transformation of energy of ultrasonic vibrations, as the need to improve the efficiency of the process based on the gradual definition of qualitative and quantitative picture of the energy in the contact zone of cavitation and technological environment and conditions of transfer of energy to the technological environment. Definition and consistent calculation of the energy conversion chain for the implementation of this idea used existing and developed new criteria for evaluating methods of acoustic treatment of technological environments: the intensity, the ratio of energies, a synergistic coefficient, coefficient of energy absorption, the rate of change of pressure in time; the wave resistance of the medium in the regimes of cavitation resistance of the initial state of the environment and others. This approach, as the process of improving existing or establishing new systems and technologies is synergistic systems. On the basis of research and evaluation of these criteria formulated synergistic principles of perfecting of conditions and parameters of the system “ultrasonic installation – technology environment”.

A facile approach to synthesis of cobalt ferrite nanoparticles with a uniform ultrathin layer of silicon carbide for organic dye removal

Dispersions of surface capped ferrite nanoparticles have many practical applications in heat transfer, optics, memory devices, sensors and biomedicine. However, capping of ferrite nanoparticles with a stable ultrathin layer of organic or inorganic materials, without compromising magnetic properties, still remains a challenge. Here, we demonstrate, for the first time, a facile and rapid approach to cap cobalt ferrite nanoparticles with a uniform ultrathin layer of silicon carbide (~1.4 nm) by using an organosilica coating agent, dichlorodimethylsilane (DCDMSi), through sonochemical approach. The ultrasonic cavitation process is exploited for aiding the rapid and effective capping of SiC over CoFe2O4 through self-restrained condensation of silanol moieties. The synthesized silicon carbide coated CoFe2O4 nanoparticles (CFSi) and uncoated CoFe2O4 (CFUC) are characterized using Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analyzer with simultaneous differential scanning calorimetry (TGA-DSC), Vibrating sample magnetometer (VSM), X-ray diffractometer (XRD), Transmission electron microscopy (TEM), Energy dispersive X-ray (EDX) and dynamic light scattering (DLS). The organic dye adsorption ability of capped particles was investigated using dyes with different functional moieties. The plausible mechanism of SiC capping, adsorption mechanism and the mode of interaction of different functional moieties are also elicited. The unique benefits of this approach include non-requirement of metal catalysts, hazardous chemicals, high temperature or pressure, long reaction time and exogenous initiators. Unlike the conventional approaches, this technique facilitates synthesis of fine magnetic nanoparticles with a uniform and robust ultrathin layer of silicon carbide. The results suggest that straight through channel dye removal by continuous feed through packed beds of CFSi particles under a magnetic field is possible without the need of centrifugation, precipitation, filtration, washing and ultrasonication.

Investigation on enhanced mechanism of heat transfer assisted by ultrasonic vibration

The technology of heat transfer enhancement assisted by ultrasonic has attracted great attention in recent years. In this work, the enhanced mechanism of heat transfer associated with ultrasonic vibration was analyzed and numerically simulated. Firstly, the sinusoidal transmission ways of ultrasound was introduced. A theory of condensation chain reaction was proposed to reveal the enhanced mechanism of heat transfer with ultrasonic. Then, the results calculated by LAMMPS were presented to verify the ultrasonic cavitation process. Finally, two examples of cross pipes and double-pipe heat exchangers were introduced to exhibit the enhanced effect of ultrasonic. The results indicated that the enhancement effect could be attributed to three factors, which are all brought about in condensation chain reaction process.

Creation of Structural Polymer Composite Materials for Functional Application Using Physicochemical Modification

The various aspects of physicochemical modification of the components of structural materials of functional application based on classical composites and nanocomposites are analyzed. Potential applications of such materials are briefly described. Ultrasonic cavitation treatment is considered as a basic method of physical modification when obtaining the indicated classes of composites. The influence of ultrasonic treatment modes on the technological and operational properties of reactoplastic polymers, as well as on the hardening of reinforced composites based on them, is investigated. Technical means of ultrasonic cavitation processing of liquid binders and polymer composites based on them are briefly described. An effective spectrum of interrelated structural and technological parameters of ultrasonic treatment has been characterized, which is established by calculation and experimentally-statistically. The design issues of the technological processes of obtaining polymer composites of functional application are analyzed. The efficiency of creating carbon fiber composite materials, as well as the prospects for creating of these materials based on reinforcing fabric with nanomodified fillers, is described. The methods of obtaining functional nanomodified carbon-composites with improved physicomechanical and operational properties, in particular with increased strength and electrical conductivity, are characterized. The effectiveness of the ultrasonic treatment and production of nanomodified thermoplastic composite materials by extrusion method is considered. Some issues of forming products from intelligent polymer composites are analyzed. The results of the survey can be used in the design of advanced technologies for the creation of functional polymer composites of functional application.

Optimization of ultrasonic cavitation processing in the liquid melt flow

Ultrasonic processing (USP) during direct-chill (DC) casting of light metal alloys is typically applied in the sump of a billet. This approach, though successful for structure refinement and modification, has two main drawbacks: (a) mixture of mechanisms that rely heavily on dendrite fragmentation and (b) a limited volume that can be processed by a single ultrasonic source. We suggest moving the location of USP from the sump to the launder and applying it to the melt flow for continuous treatment. The apparent benefits include: (a) degassing of the melt volume, (b) grain refinement through activation of non-metallic inclusions, fragmentation of primary crystals, and deagglomeration of grain refining substrates, and (c) a possibility to use a single ultrasonic source for processing large melt volumes. To optimize this process with regard to the acoustic intensity and melt residence time in the active cavitation zone, flow modification with baffles as well as informed location of the ultrasonic source are required. In this paper, we demonstrate the results of experimental trials where the degassing degree and grain refinement have been the indicators of the USP efficiency for two aluminium alloys, i.e. LM25 and AA7050. The results are supported by acoustic measurements and computer simulations.

Effect of nano SiC particles on properties and characterization of Magnesium matrix nano composites

Abstract The increasing demand and diverse design requirements with significant weight savings as well as high strength-to-weight ratio as compared to conventional materials have all raised a growing interest towards the field of composites. Ceramic silicon carbide has received wide attention because of its excellent oxidation resistance, corrosion resistance and low density and even at high temperatures. In recent years, Magnesium (Mg) matrix composites have been used in the automotive industry owing to their lightweight property. Mg matrix composites compromise a very high specific strength, excellent castability, good damping capacity and greater machinability. Nanoparticle reinforcements can considerably improve the mechanical properties of the matrix by more successfully stimulating the particle hardening mechanisms than micron-sized particles. The present paper deals with the fabrication and characterization of magnesium matrix reinforced with different wt % (0,0.5 and 1) of nano SiC particles prepared by solidification combined with ultrasonic cavitation process. Mechanical properties such as micro hardness and density and microstructure of the composites were observed. Microstructure of nano SiC composites were investigated by scanning electron microscope (SEM), X-ray diffraction (XRD) and Energy Dispersive X-ray (EDX). The results showed that the increase in weight % of nano SiC improve the mechanical properties.

Effects of Injections of Nanostructured Titanium Dioxide into the Rat Medullary Nuclei Involved in Cardiovascular Control

Effects of injections of titanium dioxide nanoparticles into the medullary nuclei involved in cardiovascular control (nuclei reticularis paramedianus, reticularis lateralis, and ambiguus) on the blood pressure and heart rate were examined in rats. The nanoparticles (TiO2, PlasmaChem GmbH, D-12489 Berlin, Germany) were used in the form of a nanopowder (mixture of rutile and anatase). The average particle size measured using a scanning electron microscope was 21 ± 5 nm, the specific surface area of the particles was 50 ± 10 m2/g, the purity exceeded 99.5%, the Al2O3 content was below 0.3 mass %, and the SiO2 content did not exceed 0.2%. The nanoparticles were dispersed in Krebs solution (pH 7.4) using ultrasonic cavitation processing for 2 min at 37 kHz. The zeta potential of TiO2 suspension was – 7.93 mV. To provide the aggregate stability of aqueous suspensions of TiO2 nanoparticles, the latter were mechanically stirred. Injections of nanosized TiO2 in the mentioned medullary nuclei induced noticeable changes in the blood pressure, which depended on the concentration and the site (nucleus) of injection. Changes in the heart rate were insignificant in all cases.

An Experimental and Modeling Study of Al-based Nanocomposites Fabricated by Ultrasonic Cavitation and Solidification Processing

In the present investigation, A356 nanocomposites were fabricated via ultrasonic stirring technology (UST) in a coreless induction furnace. SiC nanoparticles were used as the reinforcement. Nanoparticles were added into the molten metal and then dispersed by ultrasonic cavitation and acoustic streaming assisted by electromagnetic stirring. The UST was also applied during the solidification process. The nanocomposite microstructure was investigated by optical microscopy and SEM. The distribution of SiC nanoparticles in the A356 alloy matrix was also analyzed. The SEM and EDS analyses showed that both the matrix microstructure and the SiC particles dispersion into the matrix can be considerably improved when ultrasonic cavitation, induction melting and stirring, and solidification processing techniques are applied together. Molecular dynamics simulations were conducted to analyze the complex interactions between the nanoparticles and the S/L interface.

Effectiveness evaluation of molten salt processing and ultrasonic cavitation techniques during the production of aluminium based hybrid nanocomposites - An experimental investigation

The aim of this research work is to evaluate the effectiveness of two processing methods and treatments on the mechanical properties Al 7075 based hybrid nanocomposite. In this study, Al 7075 based hybrid nanocomposites were fabricated through ultrasonic assisted cavitation and molten salt processing methods, which were further subjected to T6 treatment and deep cryogenic treatment. The microstructural observation was carried out on hybrid nanocomposites using optical and scanning electron microscopy. A hybrid nanocomposite produced by molten salt processing with ultrasonic assistance and optimized mechanical stirring was found to possess superior properties in terms of tensile strength, percentage elongation and hardness over all other samples. Out of these treatments, T6 was found to better enhance the mechanical properties of aluminium alloy and hybrid nanocomposite than deep cryogenic treatment.

An Experimental and Modeling Investigation of Al-based Nanocomposites Manufactured via Ultrasonic Cavitation and Solidification Processing

In the present study, A356 based nano-composites are fabricated by using the ultrasonic stirring technology (UST) in a coreless induction furnace. SiC nanoparticles were used as the reinforcement. Nanoparticles were added into the molten metal and then dispersed by ultrasonic cavitation and acoustic streaming assisted by electromagnetic stirring. The UST was also applied during the solidification process.The microstructure of the nanocomposites has been investigated by optical microscopy and scanning electron microscopy (SEM). The distribution of SiC nanoparticles in the A356 alloy matrix has also been analyzed. The SEM and energy dispersive X-ray spectroscopy (EDS) analyses showed that the matrix microstructure of the A356 alloy and the dispersion of the SiC nanoparticles into the matrix can be significantly improved when ultrasonic cavitation, induction melting and stirring, and solidification processing techniques are used together.Molecular dynamics (MD) simulations were conducted to analyze the complex interactions between the nanoparticle and the liquid/solid interface. The assumption that nanoparticles will be engulfed by the solidification front instead of being pushed was proved through MD simulations.

The role of ultrasonic cavitation in refining the microstructure of aluminum based nanocomposites during the solidification process

Recent studies showed that the microstructure and mechanical properties of aluminum based nanocomposites can be significantly improved when ultrasonic cavitation and solidification processing is used. This is because ultrasonic cavitation processing plays an important role not only in degassing and dispersion of the nanoparticles, but also in breaking up the dendritic grains and refining the as-cast microstructure.In the present study, A356 alloy and Al2O3 nanoparticles are used as the matrix alloy and the reinforcement, respectively. Nanoparticles were added into the molten A356 alloy and dispersed via ultrasonic cavitation processing. Ultrasonic cavitation was applied over various temperature ranges during molten alloy cooling and solidification to investigate the grain structure formation and the nanoparticle dispersion behavior. Optical Microscopy and Scanning Electron Microscopy were used to investigate in detail the differences in the microstructure characteristics and the nanoparticle distribution. Experimental results indicated that the ultrasonic cavitation processing and Al2O3 nanoparticles play an important role for microstructure refinement. In addition, it was shown in this study that the Al2O3 nanoparticles modified the eutectic phase.