Papers by Keyword: Ultrasonic

Abstract: We report herein, the synthesis of colorful nanofibers by electrospinning and dyeing with various class of dyestuff. Results revealed that dyes impart better color yield with the acceptable colorimetric values, color yield and color fastness. Morphology of nanofibers showed smooth surface of the dyed nanofibers under SEM. Cellulose nanofibers in particular, were prepared using precursor cellulose acetate and then converted into cellulose under alkaline treatment. Results revealed that dyes impart better color yield with the adequate color yield (KS) and color fastness. Morphology of nanofibers showed smooth nanofibers after dyeing under SEM. Based results obtained, the colorful nanofiber can be a better choice for advance apparel applications.

Abstract: Ultrasonic inspection using b-scan (brightness scan) and its application for discontinuity and flaws detection were investigated. Brightness scan is one of the ultrasonic technique’s branches, it provides thorough image of the material which undergone inspection via density of the material where then depicted in different colour in conjunction with the acoustic impedance of the phase gone through by the sound wave. The sound wave generated with a piezoelectric transducer was propagated through aluminum wafer samples and were identified by the b-scan system. Its ability to detect flaw at certain depth which was introduced manually been examined. Experimental results show different brightness characteristic, depending on the adhesive treatments, type of material and medium when the waves pass through in each sample. Brightness scan system was proven to be reliable non-destructive testing method in ultrasonic for inspection of structural bonded materials.

Abstract: Being abundant and hazardous solid waste, the utilization of fly ash was sought. This study aimed to convert coal fly ash into zeolite using reflux method combined with microwave and ultrasonic pretreatments. Fly ash was reacted with NaOH 2 M, ultrasonicated for 30 minutes and irradiated using microwave for 45 minutes. The resulting solution was then refluxed for 24 hours. The zeolite formation was confirmed by FTIR and XRD analysis. The zeolite was then activated by 20% HCl for 2 hours. Fly ash, zeolites and activated zeolite were characterized for their adsorptive properties using a cationic dye via batch experiment. The maximum adsorption capacity (Qm) of fly ash, zeolite, and acid activated zeolite were 0.0003 mg g, 51 mg/g, and 101 mg/g, respectively. BET analyses indicated that the surface area of fly ash was 7 m2/g, while that for zeolite and acid activated zeolite were 82.4 m2g and 82.6 m2/g, respectively. The FTIR showed the Si-OH groups were significantly enhanced upon acid activation indicated by absorption peak at 960-1100 cm-1. It can be concluded that the chemisorption via cation-exchange or monolayer interaction played a major role in the adsorption mechanism of zeolite, supported by the allignment of the adsorption data plots to Langmuir isoterm adsorption model.

Abstract: An investigation has been carried out on the effects of abrasive-aided ultrasonic cavitation machining process on improving the surface roughness of 3D-printed material. The test surface will be placed in a vertical orientation aligned with the central axis of the ultrasonic horn rather than horizontally as commonly practiced. Experimental parameters of abrasive concentration and size is used and the effect on surface roughness at both vertical and horizontal distances away from the horn is examined. It is found that larger abrasive concentration has a positive effect on the depth of surface roughness improvement while a limitation is observed for larger abrasive sizes. No trend in surface roughness improvement is found with respect to the horizontal distance from the horn’s central axis.

Abstract: A method for determination of formaldehyde in water-borne coatings by high-performance liquid chromatographic was proposed. Ultrasonic water extraction method was used instead of the traditional steam distillation method can be more rapid and efficient extraction of target, filtered and derivatived with DNPH. The extract was separated by C18 column with an elution composed of acetonitrile and water, and detected at 352nm. The detection limit was 0.1mg/L. The method showed good linear correlation, R² was 0.9997 at the range of 0.1mg/L ~ 20 mg/L. Recovery was 95% ～105%. This method is simple, effective and sensitive.

Abstract: Common limitations in bulk metal forming processes are the maximum available press force and forming characteristics of metallic materials. Conventional measures to overcome those limitations, such as forming at elevated temperature, are not always applicable. An alternative approach is the use of a superimposed axial tool vibration with ultrasonic frequency. This enables a considerable reduction of required forming forces. The underlying mechanisms of this phenomenon have so far mainly been investigated for frequencies above 20 kHz and easily deformable materials, like copper. Due to limitations concerning the system technology, materials with higher strength have been considered only to a very limited extent. In order to allow investigations on the deformation behavior of materials with higher strength during ultrasonic-assisted upsetting, a tool setup containing a 15 kHz oscillating system has been developed. It offers a larger loading capacity in comparison to industrially available systems with higher frequency. Ultrasonic-assisted upsetting experiments with varying amplitude and press velocity are carried out to examine vibration-induced changes in the flow behavior of steel S235JR. Changes in the material characteristics are analyzed by evaluating the mean upsetting force as well as the microstructure of the upsetting specimen before and after forming. The resulting forces show a strong process dependence regarding the oscillation amplitude. The static press velocity and contact status between tool and specimen also influence the process forces, but to a much lower extent than the amplitude. Concerning the microstructure a rising oscillation amplitude leads to an increased radial elongation and axial compression of ferrite grains at the strongly deformed specimen center.

Abstract: To comply with increasing product requirements, the use of function-optimized materialsis claimed. Joining technology thereby becomes increasingly important to use high strength materialonly in postulated sections. Staking is a joining by forming technology that is highly reliable andcost efficient. High process forces and sufficient formability of the material limit the suitability inclaimed miniaturization for use in industrial applications. A promising approach to break these processlimitations is the use of superposed high frequency oscillation, whereby joining forces could bedecreased. The present study indicates first trials of an ultrasonic (US) assisted staking process of highstrength martensitic steel. Based on high temporal instrumentation, such as laser vibrometer, contactdetection and high-resolution force measurement, the process sequence is characterized and studiedin detail. The researches confirm high potential in force reduction of mean values due to superimposedhigh frequency oscillation with a high dependency on amplitudes. In process, two differentforce-characteristics within three regimes can be identified. Since US assisted forming processes arewell known in literature with harmonic oscillating force signals during process, hammering and soirregular force peaks with changes in contact signal within process, are identified for first time anddemonstrate a highly promising field of application.

Abstract: In this study, un-refined A383 aluminum alloy was cast at different temperatures using ultrasonic melt treatment. The liquid alloy was treated by ultrasonic vibrations in the crucible and/or in the shot sleeve of a pressure diecasting machine. The treatment temperature extended to the semisolid temperature range. The UST melt could be injected into the die cavity while being in the semisolid state which is known as rheodiecasting. The results showed that ultrasonic treatment resulted in finer microstructure, globular Fe-intermetallic particles and partially modified eutectic Si. For samples solidified in shot sleeve: Fe-intermetallics become compacted with UST at all positions of ingot. Si particles are compacted in less acicular form near to horn and acicular at other positions. For the rheo-diecasting experiments, with UST treatment in the crucible and die casting, at 600-588 C and 588-578C, Fe-intermetallics were observed in compact form, and Si particles were highly modified.

Abstract: The feasibility of using the ultrasonic melt treatment to prepare billets for thixocasting process of hypoeutectic Al-7%Si alloys was studied in this paper. The work covered the billet preparation, soaking treatments and thixocasting process, with focus on the microstructural features in each case. The results showed that the use of ultrasonic treatment in billet preparation resulted in highly uniform, fine and non-dendritic microstructures. Billets with globule sizes as small as 58 µm, and roundness of more than 0.7 were obtained by ultrasonic melt treatment. Different soaking conditions before thixocasting were done and the optimum from which was the soaking for 5 min at 580°C, which resulted in thixocast parts with excellent combination of fine globules of 80 µm and roundness of 0.7 - 0.81. The eutectic Si, as well, was greatly refined by the ultrasonic thixocasting process. Furthermore, high-Fe ultrasonic treated billets, which were thixocasted successfully, exhibited Fe-intermetallic particles in highly desirable fine compacted form. These results reveal the feasibility and competence of UST as a potential route for feedstock production.

Abstract: A novel transducer for megasonic cleaning of photomasks presents an approach that differs from previous configurations, and appears to have unique features for cleaning while minimizing damage. As the cleaning and damage processes are determined by the presence of cavitation, a thorough acoustic analysis was performed on the device, by using a calibrated hydrophone scanned at the photomask location, and a quartz photomask with embedded sensors.