Ultrasonic Frequency Research Articles

Wireless Data Transmission through Concrete Structures

Chloride ion presence in the concrete pore solution is an important factor in the initiation of rebar corrosion. Therefore, elevated chloride concentration in the pore solution needs to be detected as early as possible. For this early detection to be achieved, it is ideal to deploy sensors inside the concrete structure itself. This allows real time sampling of the pore solution which is closest to the rebar. To achieve this one needs to have a system based on wireless communication which allow the sensors to communicate within the structure. This would avoid wired communications methods, which impart fragility and implementation difficulties. This literature review paper endeavours to look at the various types of radiation which can be harnessed to penetrate through the opaque concrete structure. Potential data transmission methods utilising Radio Frequency Radiation, Ultrasonic Radiation, X-Ray Radiation and Neutron Beam Radiation physics were reviewed and evaluated against a set of parameters. The paper scores each radiation type against System Size, Power Supply Requirements, Transmission Range, Complexity of Circuits and Safety issues. Through these scores, each transmission technology was graded on its potential to act as the basis on which to build a micrometre sized intra-concrete data transmission system. The paper shows that ultrasonic radiation is the most promising radiation technology for use in this application.

ULTRASONIC INTERROGATION TECHNIQUE FOR DETECTING HATCH ANGLE VARIATIONS IN ADDITIVE MANUFACTURING BY PHONONIC LATTICE STRUCTURES

Abstract Additive Manufacturing/3D Printing (AM/3DP) has revolutionized part production by enabling the creation of intricate internal structures and complex geometries from diverse materials directly from digital design files. Among powder-based metal AM/3DP methods, Selective Laser Melting (SLM) is widely used in advanced applications such as biomedical devices and aerospace parts. Despite considerable progress in AM/3DP and SLM, at present, challenges in print quality persist, and vast resources for post-production quality assessment are allocated. The quality of SLM prints is influenced by various process and design parameters, such as the accuracy of hatch angle deposition, laser intensity/power, scanning speed of the laser beam, print line spacing, layer depth, printing chamber conditions, and the material's physical and chemical properties. Direct ultrasonic Non-Destructive Evaluation (NDE) offers comprehensive internal inspection and real-time data acquisition ability; however, in AM/3DP it faces severe limitations due to a build's intricate internal and external geometric features. In the current study, we present a Phononic Crystal Artifact (PCA)-based real-time ultrasonic NDE quality monitoring framework and show offline its utility in detecting and evaluating hatch angle variations, a critical process parameter. A PCA is substantially simpler and smaller than the actual build but represents its critical geometric and structural intricacies and mechanical properties. The current offline study demonstrates that hatch angle variations can be monitored from ultrasonic responses' spectral modal frequency peaks and wave dispersion relations.

Wireless Data Transmission through Concrete Structures

Chloride ion presence in the concrete pore solution is an important factor in the initiation of rebar corrosion. Therefore, elevated chloride concentration in the pore solution needs to be detected as early as possible. For this early detection to be achieved, it is ideal to deploy sensors inside the concrete structure itself. This allows real time sampling of the pore solution which is closest to the rebar. To achieve this one needs to have a system based on wireless communication which allow the sensors to communicate within the structure. This would avoid wired communications methods, which impart fragility and implementation difficulties. This literature review paper endeavours to look at the various types of radiation which can be harnessed to penetrate through the opaque concrete structure. Potential data transmission methods utilising Radio Frequency Radiation, Ultrasonic Radiation, X-Ray Radiation and Neutron Beam Radiation physics were reviewed and evaluated against a set of parameters. The paper scores each radiation type against System Size, Power Supply Requirements, Transmission Range, Complexity of Circuits and Safety issues. Through these scores, each transmission technology was graded on its potential to act as the basis on which to build a micrometre sized intra-concrete data transmission system. The paper shows that ultrasonic radiation is the most promising radiation technology for use in this application.

Effects of Frequency on the Performance of Ultrasonic Vibration Assisted Chemical Mechanical Polishing for Sapphire

Abstract Sapphire (Al2O3) is renowned for its exceptional properties, yet its unique natural presents a surface processing challenge. To enhance the polishing quality and efficiency, the sapphire ultrasonic vibration assisted chemical mechanical polishing (UV-CMP) has been proposed. This paper employs computational fluid dynamics (CFD) simulation and polishing experiments to investigate the action and mechanism of ultrasonic frequency on sapphire UV-CMP. The CFD simulation reveals that an increase in frequency can effectively elevate the fluid velocity, pressure, and cavitation. The enhancement in pressure, Z-direction, and resultant velocity has a positive impact on the cutting ability and utilization rate of nano-abrasives. A high frequency can enhance the physical fields of slurry, but it suppresses the growth of cavitation bubbles, and is detrimental to the number and size of abrasive particles. The best processing performance of sapphire UV-CMP is obtained at 40 kHz due to coordinated physicochemical interactions. X-ray photoelectron spectroscpy proves the product of solid-solid chemical reaction between nano-SiO2 and sapphire is softer Al2Si2O7 instead of Al2SiO5, which is beneficial to the material removal. This article provides theoretical and practical guidance for sapphire UV-CMP.

Ultrasonic fatigue of superelastic Nitinol and in situ synchrotron observation of strain and damage

Superelastic Nitinol was tested at ultrasonic frequency in the high and very high cycle fatigue regime. Thin sheet specimens were initially preloaded to mimic crimping and deployment of Nitinol implants, which lead to a sample in a multi-phase state with martensitic phase in the middle and adjacent zones with austenitic phase. In situ synchrotron X-ray diffraction (XRD) was used to monitor cyclic strains over an entire ultrasonic cycle, and to compare the results with low frequency loading. Both austenitic and martensitic regimes showed similar sinusoidal elastic deformation at cycling frequencies 0.1 Hz and 18.3 kHz, and strains were comparable over the entire gauge section of the specimen. XRD data showed progressive growth of austenitic bands in formerly martensitic areas with increasing numbers of ultrasonic cycles. This increased specimen stiffness and cyclic stresses promoting crack initiation, which nearly exclusively occurred at cracked surface inclusions. The strain versus fatigue lifetime diagram shows a pronounced change in slope below 106 cycles. The overlapping properties measured at low and ultrasonic frequency demonstrate that ultrasonic fatigue testing is in principle appropriate for rapid characterization of the cyclic properties of Nitinol.

Revealing the Potential of Star Anise Essential Oil: Comparative Analysis and Optimization of Innovative Extraction Methods for Enhanced Yield, Aroma Characteristics, Chemical Composition, and Biological Activities

ABSTRACTStar anise has been used for a long time in improving human health and curing diseases, owing to its unlimited components with complex chemical structures and a wide range of bioactivities. This study is aimed to investigate the influence of extraction methods (steam distillation, ethanol Soxhlet extraction, supercritical carbon dioxide extraction, subcritical n‐butane extraction) on the yield, aroma properties, chemical composition, and bioactivity of star anise essential oils. Electronic nose detection revealed the essential oils from subcritical extraction exhibited the most intense aroma, while the essential oils from ethanol Soxhlet extraction had a more complex aroma profile. Fourier‐transform infrared analysis showed the presence of benzene rings, carbonyl groups, C=C, and aromatic ether bonds in the essential oils extracted through different methods. The major components were heterocyclic olefins, heterocyclic oxygenates, and aromatic oxygenates, as well as certain amounts of flavonoids and polyphenols. Correlation analysis revealed the relative contents of volatile trans‐anethole, wormwood, d‐limonene, cineole, and trans‐α‐citronelene were strongly associated with the antibacterial activity of the essential oils. Similarly, the contents of volatile components (d‐limonene, cineole) and non‐volatile components (total flavonoids and total polyphenols) were strongly correlated with the DPPH scavenging activity of the essential oils. These results confirm the effectiveness of the ethanol Soxhlet extraction method in retaining the bioactivity of the essential oils. Finally, with a Box–Behnken central composite design of response surface and single‐factor experiments, the optimal extraction conditions for the ethanol Soxhlet method were determined: ultrasonic frequency of 80 kHz, crushing particle size of 60 meshes, liquid–material ratio of 8:1 (mL:g), and ultrasonic time of 35 min. Under these conditions, the essential oil yield was 25.51% ± 0.21%. Overall, these findings highlight the significance of extraction methods in obtaining high‐quality star anise essential oils with desirable aroma properties and potent bioactivities.

Numerical simulation of fluid flow characteristics and ultrasonic cavitation performance in novel-designed stirred tank sonoreactor

A novel-designed stirred tank sonoreactor was developed to well solve large-scale dispersion of nanoparticles in liquid phase system. The fluid flow characteristics and ultrasonic cavitation performance in the sonoreactor were numerically simulated by CFD method. By comparing the pressure, cavitation bubble and velocity distribution under different situations, it is found that larger ultrasonic amplitude, relatively smaller ultrasonic frequency, higher saturated vapor pressure and lower viscosity of liquid medium are beneficial to ultrasonic cavitation. Besides, the acoustic flow action is strengthened with the increase of ultrasonic frequency and decrease of gas-liquid mixture's average density. For the designed sonoreactor, it is critical that high-frequency transducers should be determined near the bottom and upper region of the kettle, and large-amplitude transducers can be confirmed in the middle position. The research findings will provide theoretical and technical supports for developing state-of-the-art sonoreactors and optimizing ultrasonic process parameters in the industrialized preparation of nanocomposites.

Impact of ultrasonic probe type, frequency, and static pressure on large-scale graphene exfoliation

The ultrasonic liquid phase exfoliation method has emerged as an essential research direction for graphene preparation due to its cost-effectiveness and ability to minimize defects. However, this method faces challenges related to processing throughput when scaled up for industrial production. In this study, industrial grade ultrasonic homogenizers with different frequencies and probe types were evaluated for the preparation of FLG. In each experiment, 1.5 kg of graphite slurry was treated using a cyclic ultrasonic system. The results demonstrated that the 25 kHz dumbbell probe produced the thinnest FLG with the lowest defect density. Moreover, applying a static pressure of 0.2 MPa in the cycle system enhanced the cavitation-induced exfoliation of graphite sheets, effectively reducing the layer count and distribution range of FLG. This method improves the conductivity while minimizing defect density.

A study of the ultrasonic and audible frequency response of commercial loudspeakers for use as parametric acoustic arrays

Parametric acoustic loudspeakers (PAL), also known as parametric acoustic arrays (PAA), are speakers that use ultrasonic waves to generate directive audible sound. They emit an ultrasonic carrier modulated in amplitude by the desired audible signal, and due to non-linear propagation in air, this signal is reproduced in the audible range. Typical applications include audio reproduction for entertainment, but also active noise control and acoustic measurement of material properties. PAA typically consist of an array of piezoelectric transducers set on a surface. However, there are other speakers in the market that, due to their characteristics, could also achieve the PAL effect. This work examines the performance of commercial speakers when reproducing. First, the ultrasonic frequency response of each speaker is examined in free-field conditions using exponential sine sweeps (ESS). This enables searching for potential carrier frequencies to modulate the ESS in the ultrasonic range. The ESS are next modulated in the desired ultrasonic region and emitted through each speaker, obtaining their audible and ultrasonic impulse responses. The results show that some commercial speakers can also operate as PALs, which is interesting from an industrial point of view as it lowers costs and simplifies the assembly process.

Sound absorption coefficient in the audible and ultrasonic frequency range measured in a reverberation chamber with an omnidirectional parametric loudspeaker

An omnidirectional parametric loudspeaker (OPL) is a sound source that contains hundreds of ultrasonic transducers set on the surface of a sphere. Each transducer emits an ultrasonic collimated beam consisting of an audible exponential sweep sine (ESS) modulated in amplitude. This results in hundreds of ultrasonic sound waves emitted in all directions, but also audible sound waves generated by the parametric acoustic array (PAA) phenomenon, by which a modulated signal returns to the audible range thanks to nonlinear propagation in the air. This work examines how the OPL performs in assessing room acoustics, specifically in determining material sound absorption coefficients within reverberation chambers. The ISO 354 standard requires measuring reverberation times with the chamber empty and with the material sample. These are measured using ESS, which has proven effective for the OPL performance. This signal concentrates all the sound power into a single frequency, which improves ultrasonic power levels and thus the signal-to-noise ratio of the audible sound field. The absorption coefficient is next evaluated following the standard, and the results are compared with those obtained using a standard dodecahedral loudspeaker. Finally, the absorption coefficient in the ultrasonic range is examined to evaluate the OPL performance in this frequency range.

Effect of ultrasonic rapid thawing on the quality of frozen pork and numerical simulation

Different ultrasonic power densities have positive implications for thawing frozen pork. This study investigated the effects of a 20 kHz ultrasonic frequency and different ultrasonic power densities (0, 10, 20, 27, 33, and 40 W/L) on the thawing loss, color, texture, pH value, and TBARS value of thawed frozen pork. It was found that ultrasonic rapid thawing significantly reduced the thawing time of frozen pork, with the shortest thawing time observed at an ultrasonic power density of 40 W/L, resulting in a 68.8% reduction in thawing time compared to static water thawing without ultrasonic treatment, and a 14.8% improvement in tenderness. When the ultrasonic power density exceeded 10 W/L, there were no significant differences in thawing loss, cooking loss, texture, color, pH value, and TBARS value of frozen pork compared to fresh pork. A numerical model of the acousto-thermal coupling of ultrasonic rapid thawing of frozen pork was also established in this study. The ultrasonic amplitude of the thawing process was visualized through numerical calculations. The predicted thawing time and thawing temperature of ultrasonic thawing showed a high degree of fit with experimental values. The average deviation (AD) of thawing time and temperature was 0.19–0.36 °C and 10–70 s. The root mean square error (RMSE) of thawing temperature was 0.09–0.32.

Effects of ultrasound on bubble dynamic behavior of flow boiling in microchannel

Bubble dynamics is paramount in comprehending the heat transfer mechanisms of flow boiling in the microchannel within ultrasonic field, which is regarded as a promising method to confront challenges of thermal management posed by microelectronic devices. Nevertheless, the impact of ultrasound on bubble behaviors and its underlying mechanisms remain largely unexplored. This study first delves into the effect of ultrasonic parameters on bubble dynamic behaviors and associated mechanisms, subsequently further analyzing the forces acting on bubbles through the constructed force model. The findings suggest that although growth force serves as the significant resistance, the primary Bjerknes force dominates the rapid detachment of bubbles. The secondary Bjerknes force results in the bubble only sliding along the bottom wall rather than lifting off. Furthermore, the elevated ultrasonic pressure amplitude resulting from augmenting ultrasonic power induces a substantial increase in the critical detachment diameter and growth rate by 55.49% and 59.42%, respectively. The enhanced primary Bjerknes force, attributed to the rise in ultrasonic frequency, leads to a 71.42% increase in sliding velocity and a 46.45% reduction in growth time. The positive impacts arising from ultrasonic power and frequency are anticipated to notably enhance the thermal performance of microchannels. Besides, surface tension acts as the resistance and diminishes slightly with an augmentation of the boiling number, resulting in a moderate variation in sliding velocity and growth time.

Experimental Study Of Anisotropic And Dispersion Signature Of Shale Reservoirs: Implications For Synthetic Seismic Well Tie

To investigate velocity anisotropy and dispersion in lacustrine shales, we conducted laboratory measurements of acoustic properties at seismic frequencies (2–100 Hz) and ultrasonic frequencies (1 MHz) under varying effective pressures. Our study reveals significant transverse isotropy, accompanied by notable velocity dispersion and attenuation, with anisotropy coefficients ranging from 0.45 to 0.74 for P-waves and 0.44 to 0.95 for S-waves. Attenuation exhibited weak dependence on frequency and pressure but showed a strong positive correlation with clay content. We interpreted the data by integrating geological and physical analyses. Using rock physics modeling and the propagation matrix method, we found that velocity dispersion primarily caused the mismatch between seismic data and synthetic seismograms, while anisotropy had minimal impact on near-offset seismic data. Our findings suggest that anisotropy and dispersion observed at the core scale persist at the seismic scale. Incorporating these effects into seismic workflows is crucial for improving data processing, inversion, and reservoir characterization. This study provides valuable insights for exploration and production strategies in the study area and similar settings.

First applications of ultrasound technology in solid rocket propellant combustion promotion

The regulation of propellant combustion using ultrasonic waves is proposed. Under ultrasonic frequencies of 25–40 kHz, we systematically examined the combustion characteristics of Al particles, ammonium perchlorate (AP)/hydroxyl-terminated polybutadiene (HTPB) propellants, and Al-containing Al/AP/HTPB propellants. Ultrasonic treatment increased the ignition delay time of the Al particles by 48.3 %. However, it increased the burning rate of the AP/HTPB propellants by up to 26.1 % and decreased their ignition delay by 39.3 %. As the ultrasonic frequency increased, the burning rate of the solid Al/AP/HTPB propellants increased by 22.5 %, and the degree of Al agglomeration decreased, resulting in a 24 % decrease in the size of the condensed-phase combustion products. The action mechanism was analyzed in terms of the effects of ultrasonic waves on Al droplets and combustion flames. The introduction of ultrasonic waves split the Al droplets near the burning surface into smaller particles, which affected combustion efficiency. Bringing the diffusion flame closer to the burning surface affected the burning rate. These findings demonstrate that the combustion and agglomeration characteristics of solid propellants can be modified using ultrasonic techniques, providing a new method for controlling the thrust of solid rocket motors.

Receptivity of Rayleigh-Taylor instability to acoustic pulses: Theoretical explanation of pulse propagation

Direct numerical simulation (DNS) of Rayleigh-Taylor instability (RTI) has been reported in “Three-dimensional (3D) DNS of RTI triggered by acoustic excitation - Sengupta, et al. Phys. Fluids 34(5), 054108 (2022)” using more than 4 billion points with initial time steps of 7.69 ×10−8s. The set-up consists of quiescent heavy (cold) fluid atop lighter (hot) fluid initially separated by an insulated partition. Removal of this partition creates acoustic pulses in the directions normal to the interface, which provides the receptivity route of RTI to transient acoustic pulses spread over several mega-Hz frequencies, far in excess of ultrasonic frequencies. The DNS and its analysis reveal the pulses to be severely attenuated, which cannot be explained by the classical wave equation. In the present research, after demonstrating the features of the DNS results, we report in detail, the theoretical development of a wave equation incorporating losses based on the Navier-Stokes equation without Stokes' hypothesis for a quiescent ambience. Apart from the physical properties of this altered wave equation, the numerical solution of the same is obtained. The governing partial differential equation (PDE) for the propagation of disturbances in the spectral plane, provides the dispersion relation between wavenumber and circular frequency in the dissipative medium accounting for viscous losses. The presented analysis provides physical properties using the global spectral analysis (GSA). This shows the far-field perturbation to propagate either as attenuated waves or strictly in a diffusive manner depending upon the wavenumber. The PDE is solved numerically by a high-accuracy compact scheme and the four-stage, Runge-Kutta scheme for time advancement. The computed solution is shown to match not only with the developed theoretical analysis but also explains the DNS results for RTI at early times when the computed flow field truly represents the quiescent ambience.

On the Dynamics of a Novel Liquid-Coupled Piezoelectric Micromachined Ultrasonic Transducer Designed to Have a Reduced Resonant Frequency and Enhanced Ultrasonic Reception Capabilities.

This paper introduces a novel design for a liquid-deployed Piezoelectric Micromachined Ultrasonic Transducer (PMUT). This design was specifically developed to resonate at a lower ultrasonic frequency than a PMUT with a circular, fully clamped diaphragm with the same diameter. Furthermore, the novel design was also optimised to enhance its ultrasonic radiation reception capabilities. These parametric enhancements were necessary to develop a PMUT device that could form part of an eventual microscale sensory device used for the Structural Health Monitoring (SHM) of reinforced concrete (RC) structures. Through these two enhancements, an eventual microscale sensor can be made smaller, thus taking up a smaller die footprint and also be able to be deployed further apart from each other. Eventually, this would reduce the developed distributed sensor system's cost. The innovative design employed a configuration where the diaphragm was only pinned at particular points along its circumference. This paper presents results from Finite Element Modelling (FEM), as well as experimental work that was conducted to develop and test this novel PMUT. The experimental work presented involved both laser vibrometry and ultrasonic radiation lab work. The results show that when compared to a clamped diaphragm design, the novel device managed to achieve the required reduction in resonant frequency and presented an enhanced sensitivity to incoming ultrasonic radiation.

A New Process of Chemical Plating Ni-P Electromagnetic Induction Heating Activation on the Surface of Aluminium Alloy Base Material

Nowadays, there are many surface treatment methods for aluminium alloys; the most commonly used of these is the chemical dip galvanizing process, which is complicated due to its use of large quantities of corrosive drugs. In order to simplify the process, this paper proposes a new electromagnetic induction heating activation method instead of the zinc dipping process. The method works as follows: The substrate is first degreased and then activated. The activation process starts by soaking the degreased substrate in an activation solution, taking it out after ten minutes, and placing it into an induction heating unit. The activation solution is sprayed onto the surface of the substrate while heating, using the energy generated by high temperatures to complete the activation reaction. The surface of the activated substrate forms a nanoscale film of nickel, which is finally utilised as a catalytic centre for ENP (an advanced surface treatment process that deposits a very uniform layer). The optimisation of important parameters of the non-destructive activation process was determined using the L9 Taguchi method. The main parameters ranged from 0.15 L/min to 0.25 L/min for spray rate, 200 °C to 400 °C for heat treatment temperature, and 1:4, 1:5, and 1:6 for Ni2+ and H2PO4− ion concentration ratios. The above data were derived from a single variable and were analysed using Minitab 20 software. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), energy spectrometry (EDS), and ultrasonic experiments were used to characterize and analyse the surface morphology, composition, and bond strength of the coatings. The results show that the nanoscale nickel particles can completely cover the surface of the substrate, forming a layer of nano-film. After activation and ultrasonic cleaning for 30 s at an ultrasonic frequency of 40 KHz and a power of 80 W, the surface nano-film was not destroyed, which proves that it had a high bonding strength. After the application of the plating, the plated surface had a compact microstructure, and the continuity was good. Therefore, compared with the currently commonly used zinc dipping process, this process has the advantages of being a low-cost, simple operation, and non-destructive and environmentally friendly activation process for the substrate.

A Comprehensive Review of Piezoelectric Ultrasonic Motors: Classifications, Characterization, Fabrication, Applications, and Future Challenges.

Piezoelectric ultrasonic motors (USMs) are actuators that use ultrasonic frequency piezoelectric vibration-generated waves to transform electrical energy into rotary or translating motion. USMs receive more attention because they offer distinct qualities over traditional magnet-coil-based motors, such as miniaturization, great accuracy, speed, non-magnetic nature, silent operation, straightforward construction, broad temperature operations, and adaptability. This review study focuses on the principle of USMs and their classifications, characterization, fabrication methods, applications, and future challenges. Firstly, the classifications of USMs, especially, standing-wave, traveling-wave, hybrid-mode, and multi-degree-of-freedom USMs, are summarized, and their respective functioning principles are explained. Secondly, finite element modeling analysis for design and performance predictions, conventional and nano/micro-fabrication methods, and various characterization methods are presented. Thirdly, their advantages, such as high accuracy, small size, and silent operation, and their benefits over conventional motors for the different specific applications are examined. Fourthly, the advantages and disadvantages of USMs are highlighted. In addition, their substantial contributions to a variety of technical fields like surgical robots and industrial, aerospace, and biomedical applications are introduced. Finally, their future prospects and challenges, as well as research directions in USM development, are outlined, with an emphasis on downsizing, increasing efficiency, and new materials.

Feasibility of ultrasonic non-destructive testing of ancient funerary urns: Experimental and analytical parametric model

Non-invasive modalities are being developed as the computer tools and industrial non-destructive testing capabilities become more widespread. Using the same investigation methods as those applied to modern objects, we seek to study ancient funerary urns containing human bones. The exploration of ancient urns is key to increasing our understanding of the practices of burial and cremation in archaeo-anthropology. But those urns present at archaeological sites are exposed to diversified environments (wet, temperate or dry environment), and can be subjected to chemical or mechanical destructive actions over time. As ancient funeral urns containers are sometimes made of lead, stone or ceramic, the use of X-ray scanners is difficult or even impossible for in situ control. In this work, we propose an engineering technique based on ultrasonic non-destructive testing and wave propagation in urns. An analytical parametric model is developed using mathematical signal processing tools and validated by means of laboratory experiments under controlled conditions of propagation through reproductions of ancient urns for two ultrasonic frequencies (500 kHz and 1 MHz). The aim is to characterise an ancient urn by creating an analytical model, and to use a parametric identification algorithm to determine the presence or absence of bone fragments. The parametric identification algorithm based on the Levenberg–Marquardt method makes it possible to determine the geometrical (thickness) and physical (wave velocity and attenuation, mass density) parameters when the urn is filled with water, with water and bones, and with water, bones and sand. We show that the model makes it readily (processing time ≈15 sec) possible to find the different times of flight between the transducer and the different walls of the urn and the parameters with an accuracy less than 10%.

Ultrasonic-assisted stripping of single-crystal SiC after laser modification

Laser stripping technology is an advanced processing method with high efficiency and low material loss, which can greatly reduce material loss in the production process of single-crystal SiC wafer, but the single-crystal SiC ingot still have a certain bonding force after laser modification. Ultrasonic vibration can reduce the bonding force and thus strip single-crystal SiC wafer. In order to investigate the effect of ultrasonic vibration on the reduction of the bonding force of single-crystal SiC internal modification layer, through the ultrasonic-assisted stripping of single-crystal SiC orthogonal experiment, the ultrasonic vibration parameters of ultrasonic frequency, vibration time and ultrasonic power of the three indexes of the reduction of the bonding force was analyzed. The results show that the bonding force of the modified layer decreased by 25 %–60 % after ultrasonic vibration. Variance analysis of the experiment results showed that the main factors influencing the bond strength reduction were vibration time and ultrasonic power in turn. When the vibration time is longer and the ultrasonic power is higher, the stripping force decreases more, and the stripping force of single-crystal SiC wafers decreases up to 60 % under the condition of vibration time of 5min and ultrasonic power of 700 W. Through analysis of the single-crystal SiC cross-section, distinct cleavage steps and cleavage channels are evident. The laser-modified region exhibits defect such as nano-pores, micro-cracks, and nano-particles.After the single-crystal SiC laser modification process was upgraded, the distance between the ultrasonic tool head and the single-crystal SiC was 1.5 mm can directly strip off the single-crystal SiC wafer. And eventually stripped 6-inch single-crystal sic wafers. Therefore, ultrasonic vibration can increase the internal defects in the single-crystal SiC modified layer, causing crack expansion to occur and ultimately stripping the single-crystal SiC wafer.