Ultrasonic Generator Power Research Articles

CHARACTERIZATION OF ZINC OXIDE NANOPARTICLES PREPARED BY SONOCHEMICAL METHOD WITH DIFFERENT ULTRASONIC EXPOSURE POWER

In the present study ZnO nanoparticles have been synthesized using sonochemical technique at different ultrasonic exposure power. The powers were 20%, 40% and 60% of the total power of ultrasonic generator (operating at 20 kHz with a maximum power output of 250 W). The experimental procedures were carried out in Ultrasonic Lab, National Institute for Standards, Egypt. ZnO nanoparticles samples were investigated by X-ray diffraction (XRD), Transmission Electron Microscope (TEM), UV visible Absorption and Fourier Transform Infrared Spectroscopy (FTIR). XRD and TEM results reveal that Exposure power has a pronounced effect on both particle size as well as morphology. The greater the exposure power, the larger the particle size. In addition, the morphology of ZnO nanoparticles modified from rod-like shape to semi-spherical shape by raising the exposure power. The band gap for all samples estimated by UV absorption data was found to be around 3.1 eV. The ZnO absorption band was observed at 560 cm-1 in FTIR spectra.

Ultrasonic-assisted synthesis of the nanostructures of a Co(II) metal organic framework as a highly sensitive fluorescence probe of phenol derivatives.

Nanostructures of a metal-organic framework with chemical formula, [Co(BDC)(L*)]n.DMF (TMU-40), BDC = 1,4-benzendicarboxylate, L* = 5,6-dipyridin-4-yl-1,2,3,4-tetrahydropyrazine, under ultrasonic irradiation at ambient temperature and atmospheric pressure were prepared and characterized by Fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). Sonication time, concentration of initial reagents and ultrasonic generator power effects on the size and morphology of nano-structured compounds were studied. TMU-40 (for Tarbiat Modares University) displayed a good potential as a luminescent sensor against phenol derivatives consist of phenol, 4-aminophenol, 4-methylphenol and 4-chlorophenol. Nano-sized TMU-40 showed the better sensing performance in comparison to its bulk phase. The nano TMU-40 displayed very selective and sensitive in detection of phenol derivatives. The detection limit amounts of 15 nM and 63 nM were achieved for 4-aminophenol in nano TMU-40 and bulk TMU-40, respectively. The special structure and fluorescent character of L* ligand and high surface area of nano MOF provide an effective interaction between MOF and phenolic analytes to selectively and sensitively detect of the analyte molecules.

Intensification of Washing of Filter Materials Using Ultrasound

Experiments on washing of filter materials to remove uranium and REE (Ce) oxides using a Grad ultrasonic bath (model 180-35) with the generator power of 300 W and frequency of 35 kHz were performed. The following filter materials were tested: MTF metal fabric filter, high-performance fiberglass cellular folded filter (FYaS-E 13 N 0 05.1 P), two types of metal fabric filters with other gauze size, T-13 glass fabric [GOST (State Standard) 19170-2001 (19170-93)] and fine air cleaning filter (FTOV N13 270 × 640 × 500–11) made of glass paper based on microthin fiberglass. The influence exerted on the washing efficiency by the treatment time, ultrasonic generator power, working solution acidity, and process temperature was examined. Ultrasonic treatment intensifies washing of filter materials to remove surrogate powders based on UO2 and CeO2. More efficient washing of fiberglass filter materials requires increased power of the ultrasonic generator.

An Experimental Investigation of Grinding Force in Ultrasonic Vibration Assisted Internal Grinding for SiC Ceramics

This paper mainly describes the using self-designed ultrasonic vibration assisted internal grinding (UAIG) spindle on SiC ceramic materials for the experimental research on grinding force, and the different parameters of ultrasonic assisted grinding force were measured and analyzed. Meanwhile, the general grinding force and ultrasonic vibration assisted grinding force are compared. The results show that the UAIG can significantly reduce the grinding force, at the same time increase the power of ultrasonic generator helps to further reduce the grinding force.

Evaluation of Very High Cycle Fatigue Properties of Low Temperature Nitrided Ti-6Al-4V Alloy Using Ultrasonic Testing Technology

Fatigue tests were carried out at the stress ratio R = -1 using a 20 kHz ultrasonic testing facility to investigate the effects of low temperature nitriding on the fatigue properties of Ti-6Al-4V alloy in the very high cycle fatigue (VHCF) regime in detail. The oscillation and fatigue behavior of the nitrided Ti-alloy were characterized by measuring parameters like the ultrasonic generator power, the displacement of the specimens and dissipated energy under ultrasonic cyclic load. Moreover, the surface microstructure of the nitrided Ti-alloy was characterized using a micro-Vickers hardness tester, an optical microscope, scanning electron microscopy (SEM), X-ray diffraction (XRD) and electron backscatter diffraction technique (EBSD) to clarify the fatigue fracture mechanism. The Ti-alloy nitrided at the temperature of 873 K showed duplex S-N properties consisting of the respective fracture modes of the surface fracture and the subsurface fracture. The low temperature nitriding reduced the surface fatigue life of Ti-alloy in comparison to the un-nitrided one due to the formation of a brittle titanium nitride (Ti2N), whereas the subsurface fatigue life in the VHCF regime was increased by the low temperature nitriding. In addition, the fatigue fracture mechanisms of the low temperature nitrided Ti-alloy were discussed from viewpoints of fractography and fracture mechanics.

Sonocatalytic removal of an organic dye using TiO2/Montmorillonite nanocomposite

The sonocatalytic performance of the synthesized TiO2/Montmorillonite K10 (TiO2/MMT) nanocomposite was studied in removal of Basic Blue 3 (BB3) from water. The TiO2/MMT nanocomposite was prepared by hydrothermal method. Scanning electron microscope, X-ray diffraction and Fourier transform infrared were used to characterize the synthesized nanocomposite. The average size of TiO2 nanoparticles decreased from 60–80nm to 40–60nm through the immobilization of this semiconductor on the surface of MMT. The obtained results indicated that the sonocatalytic activity of TiO2/MMT nanocomposite was higher than that of pure TiO2 nanoparticles and MMT particles. Furthermore, the main influence factors on the sonocatalytic activity such as the BB3 concentration, pH of solution, TiO2/MMT dose, power of ultrasonic generator, and inorganic salts were studied. The intermediates of BB3 degradation during the sonocatalytic process in the presence of the TiO2/MMT nanocomposite have been monitored by gas chromatography–mass spectrometry.

Analysis of fatigue properties and failure mechanisms of Ti6Al4V in the very high cycle fatigue regime using ultrasonic technology and 3D laser scanning vibrometry

Accelerated fatigue tests with Ti6Al4V were carried out using a 20kHz ultrasonic testing facility to investigate the cyclic deformation behavior in the Very High Cycle Fatigue (VHCF) regime in detail. Beside parameters like the ultrasonic generator power and the displacement of the specimen, a 3D laser scanning vibrometer was used to characterize the oscillation and fatigue behavior of the Ti-alloy. The course of the S–Nf curve at the stress ratio R=−1 shows a significant decrease of the bearable stress amplitude and a change from surface to subsurface failures in the VHCF regime for more than 107 cycles. Microscopic investigations of the distribution of the α- and β-phase of Ti6Al4V indicate that inhomogeneities in the phase distribution are reasons for the internal crack initiation. High resolution vibrometry was used to visualize the eigenmode of the designed VHCF-specimen at 20kHz in the initial state and to indicate local changes in the eigenmodes as a result of progressing fatigue damage. Non-contact strain measurements were realized and used to determine the stress amplitude. The determined stress amplitudes were correlated with strain gauge measurements and finite element analysis.

Monitoring and Research of Power Ultrasonic Honing Vibration Frequency

Aiming at amplitude decay with the change of the varying conditions problems in ultrasonic honing processing, this paper puts forward to the frequency of ultrasonic machining testing solutions. By measuring the change of the input current transducer, adjust the ultrasonic generator power output, and ensure that the ultrasonic generator adjust the output power according to load. Finally, stable amplitude, make the whole system in a resonant state, the amplitude of the oil-stone keep near biggest amplitude. This paper designed circuit measuring the current which can feedback current changes effectively, to provide the safeguard for adjusting the ultrasonic generator output power.

Use of ultrasonic waves in sub-cooled boiling

This work focuses on the use of ultrasounds in heat transfer fields. Under particular conditions, ultrasonic waves induce a convection coefficient increase. This initial research work, indicates that there are some practical applications in the cooling of the latest generation electronic components.In the first part of this paper, some background on this subject is reported. The ultrasound's influence on heat transfer rate has been observed since the 60's: different authors studied the cooling effect due to ultrasonic waves from different heat transfer regimes. The most investigated configuration was a thin platinum wire immersed in water. Later, a bibliographic research on possible practical applications of ultrasounds was carried out. This research focused in particular on the issue for 3D highly integrated electronic components. For these systems the thermal problem is a major challenge, because they cannot exceed critical temperatures, after which they could be damaged irreversibly. On the basis of our experimental results, ultrasounds could represent a valid means to overcome these thermal problems.Finally, the paper presents a series of experiments performed in the Thermal-Fluid- Dynamic Lab at the Energy and Engineering Systems Department of the University of Pisa. The experiments provide systematic evidence of ultrasonic waves effects, on free convection heat transfer, from a heated circular cylinder to sub-cooled water, at atmospheric pressure. Many variables involved in the heat transfer rise were tested, for example: the ultrasonic generator's power, the position of the heater inside the ultrasonic tank, the variation of the water sub-cooling degree, as function of the heat flux needed dissipating. The aim of the experiment was to find out the set of optimal conditions, in order to successively apply all the results to real packaging systems, as mentioned before. The maximum increase in the heat transfer coefficient, due to ultrasonic waves, was 57%.

Lower sintering temperature of nanostructured dense ceramics compacted from dry nanopowders using powerful ultrasonic action

Nanostructured high dense zirconia ceramics have been sintered from dry nanopowders compacted by uniaxial pressing with simultaneous powerful ultrasonic action (PUA). Powerful ultrasound with frequency of 21 kHz was supplied from ultrasonic generator to the mold, which was the ultrasonic wave-guide. Previously the mold was filled by non-agglomerated zirconia nanopowder having average particle size of 40 nm. Any binders or plasticizers were excluded at nanopowder processing. Compaction pressure was 240 MPa, power of ultrasonic generator at PUA was 1 kW and 3 kW. The fully dense zirconia ceramics has been sintered at 1345°C and high-dense ceramics with a density of 99.1%, the most grains of which had the sizes Dgr ≤ 200 nm, has been sintered at low sintering temperature (1325°C). Applied approach prevents essential grain growth owing to uniform packing of nanoparticles under vibrating PU-action at pressing, which provides the friction forces control during dry nanopowder compaction without contaminating binders or plasticizers.

Effects of Ultrasounds on the Heat Transfer Enhancement From a Circular Cylinder to Distilled Water in Subcooled Boiling

The main aim of this work is to investigate experimentally the influence of ultrasonic waves, on the heat transfer enhancement, from a stainless steel circular cylinder to distilled water, in subcooled boiling conditions. This study has carried on for a few years at the Department of Energetics “L.Poggi.” The effect was observed since the 1960s: Different authors had investigated the cooling effect due to the ultrasonic waves at different heat transfer regimes, especially from a thin platinum wire to water. They had found out that the highest heat transfer coefficient enhancement was in subcooled boiling conditions. So this paper has the purpose to clarify the physical phenomenon and optimize a large range of variables involved in the mechanism. It reports the experimental results obtained with ultrasound at the frequency of 38 kHz, at two different subcooling degrees, ΔTsub=25°C and 35°C. The heat fluxes applied on the cylinder, the ultrasonic generator power Pgen, and also the placement of the heater inside the ultrasonic generator tank were varied. The ultrasonic waves seem to be very useful for a practical application in the last generation electronic components’ cooling: They need dissipating huge heat fluxes and avoiding high temperatures (≈150°C), after that they could damage themselves.

Grain-size analysis of silicon powder

The results of the silicon powder grain-size composition found with the use of an optical microscope, Analysette-22 NanoTec laser diffraction microanalyzer, and SF-2 scanning photosedimentometer are presented. Choosing the dispersion conditions, in particular, the properties of a dispersive liquid and the ultrasonic generator power, is of great importance in setting a powder sample for analysis. Comparing three analytical procedures, one may note that the laser diffraction method offers a number of advantages over the other two; a wide measurement range, considerable number of processible particles, and short analysis time are among the advantages. Obtaining an undistorted image of an object under investigation is an advantage of optical microscopy.

Effects of ultrasonic waves on the heat transfer enhancement in subcooled boiling

This work represents an experimental basic research aimed to investigate the influence on the heat transfer rate of the ultrasounds, in free convection and in presence of liquid. In fact the ultrasonic waves induce, thanks to vibrations, turbulence on the dynamic field, and so an increase of the convection coefficient. The heater is a circular cylinder, immersed in distilled water, and warmed up by Joule effect. This study has carried on for 1 year at Energetics Department “L. Poggi”. The effect was observed since 1960s: different authors had studied the cooling effect due to the ultrasonic waves at different heat transfer regimes, especially from a thin platinum wire to water. We have chosen to investigate the subcooled boiling regime, because this one is the best condition for the heat transfer enhancement, according to the scientific literature. We have carried out a wide experimental study, varying the different water subcooling degrees, the ultrasonic generator power, the ultrasound frequency and the placement of the heater inside the ultrasonic tank, in function of the range of the values of heat flux per unit surface needed dissipating. These values were supplied us by a possible practical application of the ultrasonic streaming: the cooling of 3D highly integrated electronic components. These packaging systems should have to provide all future devices, such as electronics, actuators, sensors and antenna. In fact, for these systems the thermal problem is a critical challenge, because they do not have to overtake critical temperature, after that they could damage irreversibly. Moreover, the traditional cooling systems used in electronic do not seem to be useful for them. On the contrary, the results obtained with ultrasounds, allow heat transfer coefficient enhancement of about 50% to be reached. The purpose is to find out the set of optimal conditions, in order to apply successively all the results to a real packaging system.

The ultrasonically assisted metals recovery treatment of printed circuit board waste sludge by leaching separation

This paper provides a practical technique that realized industrial scale copper and iron separation from printed circuit board (PCB) waste sludge by ultrasonically assisted acid leaching in a low cost, low energy consumption and zero discharge of wastes manner. The separation efficiencies of copper and iron from acid leaching with assistance of ultrasound were compared with the one without assistance of ultrasound and the effects of the leaching procedure, pH value, and ultrasonic strength have been investigated in the paper. With the appropriate leaching procedure, a final pH of 3.0, an ultrasonic generator power of 160 W (in 1 l tank), leaching time of 60 min, leaching efficiencies of copper and iron had reached 97.83% and 1.23%, respectively. Therefore the separation of copper and iron in PCB waste sludge was virtually achieved. The lab results had been successfully applied to the industrial scaled applications in a heavy metal recovery plant in city of Huizhou, China for more than two years. It has great potentials to be used in even the broad metal recovery practices.

Material Removal Rate Characteristics in Ultrasonic Aided Lapping of Engineering Ceramics Based on Single-Point Scratch

A new ultrasonic aided lapping technology was developed by combining lapping technology and ultrasonic machining technology. The appended special tangential ultrasonic vibration changes the material removal rate (MRR) characteristics. In order to clarify the influence of ultrasonic vibration, in this paper, the MRR models in ultrasonic aided single-point scratch were deduced based on indentation fracture theory. Through contrast scratching and lapping experiments, the MRR characteristics in ultrasonic aided lapping of engineering ceramics were presented. Research result shows that the MMR in ultrasonic aided lapping is larger than that in conventional lapping under the same conditions; with the increase of ultrasonic generator power and lapping pressure, the MMR in lapping increases correspondingly.

Wire-bonding process development for low- k materials

A 60-μm bond-pad-pitch wire-bonding process was developed using test dies with a SiO 2 dielectric layer under aluminium pads, and was then fine-tuned for a low- k device using three types of gold wires with different mechanical properties. Bulk material hardness of the wires were characterised using a wire-bonding machine, the force applied and diameters of squashed free-air balls. It was found that stiffer wires needed higher ultrasonic-generator (USG) power than a softer wire to deform the ball after impact and achieve equivalent ball size and ball shear responses. Longer bond time was also needed for the low- k material than the SiO 2 material, to overcome the energy loss due to the compliance of the low- k material. Pad damage on the low- k device was proportional to bulk material hardness. The soft 4N (99.99% purity) wire required lower USG power to achieve the bonding specification, and was the most suitable wire to be used in wire bonding of the low- k device.