Effect of ultrasonic vibrations on the emission stability of a point tip autoelectronic cathode

Enhancing water purification processes is provided by various methods including physical ones, in particular, exposure to ultrasonic vibrations. The change in the dynamic viscosity of water affects the rate of deposition of particles in the aquatic environment which can be used in natural and wastewater treatment. At the Department Water Supply and Wastewater Disposal of the National Research Moscow State University of Civil Engineering experimental studies were conducted under laboratory conditions to study the effect of ultrasound on the change in the dynamic viscosity of water. A laboratory setup has been designed consisting of an ultrasonic frequency generator of the relative intensity, a transducer (concentrator) that transmits ultrasonic vibrations to the source water, and sonic treatment tanks. Experimental studies on the impact of the ultrasonic field in the cavitation mode on the dynamic viscosity of the aqueous medium were carried out the exposure time was obtained to achieve the maximum effect.Интенсификация процессов очистки воды осуществляется с помощью различных методов, в том числе и физических, в частности воздействием ультразвуковых колебаний. Изменение динамической вязкости воды влияет на скорость осаждения частиц в водной среде, что может быть использовано в процессах очистки природных и сточных вод. На кафедре Водоснабжение и водоотведение Национального исследовательского Московского государственного строительного университета в лабораторных условиях проведены экспериментальные исследования по изучению влияния ультразвука на изменение динамической вязкости воды. Разработана схема лабораторной установки, состоящая из генератора ультразвуковых частот с соответствующей интенсивностью, преобразователя (концентратора), передающего ультразвуковые колебания в исходную воду, и емкости для озвучивания. Выполнены экспериментальные исследования по влиянию ультразвукового поля в режиме кавитации на динамическую вязкость водной среды, получено время экспозиции для достижения максимального эффекта.

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Use of ultrasonic surface hardening in modifi cation of surface layer

10.36652/1813-1336-2020-16-5-200-204 ◽

2020 ◽

pp. 200-204

Author(s):

Yu.S. Semenova ◽

A.G. Samul’ ◽

S.V. Mazhuga

Keyword(s):

Surface Layer ◽

Chemical Treatment ◽

Surface Hardening ◽

Manufacturing Cost ◽

Ultrasonic Vibrations ◽

Surface Microrelief ◽

Scientific Schools ◽

Structure Changes ◽

Wide Range ◽

Finishing Machining

Overview of the research results got by various scientific schools in the field of application of ultrasonic surface hardening is provided. Wide range of opportunities of ultrasonic surface hardening is shown for the application in the preliminary machining of surfaces before thermal and chemical treatment, coating, and also as finishing machining. The effect of the energy of ultrasonic vibrations on structure changes in the material of the surface layer and on surface microrelief on parts performance is considered. The prospects of using of the ultrasonic surface hardening method in combination with other methods of the material modification are presented. In addition the possibilities of reducing the manufacturing cost of product by introducing ultrasonic surface hardening into the technological process are shown.

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Screen-printed Dual-Particle-Containing Multicomponent-Blending Carbon Nanotube Cathode: Enhancement of Electron Emission Characteristics, Current Emission Stability, and Uniformity

Transactions on Electrical and Electronic Materials ◽

10.1007/s42341-021-00319-y ◽

2021 ◽

Author(s):

Yu-kui Li ◽

Wen-xiu Wang ◽

Chao Wu ◽

Juan Yang

Keyword(s):

Carbon Nanotube ◽

Electron Emission ◽

Emission Characteristics ◽

Emission Stability ◽

Current Emission ◽

Screen Printed

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Ultrasound Effect on the Microstructure and Hardness of AlMg3 Alloy under Upsetting

Materials ◽

10.3390/ma14041010 ◽

2021 ◽

Vol 14 (4) ◽

pp. 1010

Author(s):

Przemysław Snopiński ◽

Tibor Donič ◽

Tomasz Tański ◽

Krzysztof Matus ◽

Branislav Hadzima ◽

...

Keyword(s):

Flow Stress ◽

Ultrasonic Vibration ◽

Light And Electron Microscopy ◽

Load Flow ◽

Forming Limit ◽

Ultrasonic Vibrations ◽

Softening Effect ◽

Simultaneous Application ◽

Ultrasonic Assisted ◽

Acoustic Softening

To date, numerous investigations have shown the beneficial effect of ultrasonic vibration-assisted forming technology due to its influence on the forming load, flow stress, friction condition reduction and the increase of the metal forming limit. Although the immediate occurring force and mean stress reduction are known phenomena, the underlying effects of ultrasonic-based material softening remain an object of current research. Therefore, in this article, we investigate the effect of upsetting with and without the ultrasonic vibrations (USV) on the evolution of the microstructure, stress relaxation and hardness of the AlMg3 aluminum alloy. To understand the process physics, after the UAC (ultrasonic assisted compression), the microstructures of the samples were analyzed by light and electron microscopy, including the orientation imaging via electron backscatter diffraction. According to the test result, it is found that ultrasonic vibration can reduce flow stress during the ultrasonic-assisted compression (UAC) process for the investigated aluminum–magnesium alloy due to the acoustic softening effect. By comparing the microstructures of samples compressed with and without simultaneous application of ultrasonic vibrations, the enhanced shear banding and grain rotation were found to be responsible for grain refinement enhancement. The coupled action of the ultrasonic vibrations and plastic deformation decreased the grains of AlMg3 alloy from ~270 μm to ~1.52 μm, which has resulted in a hardness enhancement of UAC processed sample to about 117 HV.

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Effect of Water-Based Nanolubricants in Ultrasonic Vibration Assisted Grinding

Journal of Manufacturing and Materials Processing ◽

10.3390/jmmp2040080 ◽

2018 ◽

Vol 2 (4) ◽

pp. 80 ◽

Cited By ~ 1

Author(s):

Mir Molaie ◽

Ali Zahedi ◽

Javad Akbari

Keyword(s):

Surface Roughness ◽

Specific Energy ◽

Material Removal ◽

Normal Force ◽

Tangential Force ◽

Process Efficiency ◽

Multiwall Carbon Nanotube ◽

Ultrasonic Vibrations ◽

Mql Grinding ◽

Water Based

Currently, because of stricter environmental standards and highly competitive markets, machining operations, as the main part of the manufacturing cycle, need to be rigorously optimized. In order to simultaneously maximize the production quality and minimize the environmental issues related to the grinding process, this research study evaluates the performance of minimum quantity lubrication (MQL) grinding using water-based nanofluids in the presence of horizontal ultrasonic vibrations (UV). In spite of the positive impacts of MQL using nanofluids and UV which are extensively reported in the literature, there is only a handful of studies on concurrent utilization of these two techniques. To this end, for this paper, five kinds of water-based nanofluids including multiwall carbon nanotube (MWCNT), graphite, Al2O3, graphene oxide (GO) nanoparticles, and hybrid Al2O3/graphite were employed as MQL coolants, and the workpiece was oscillated along the feed direction with 21.9 kHz frequency and 10 µm amplitude. Machining forces, specific energy, and surface quality were measured for determining the process efficiency. As specified by experimental results, the variation in the material removal nature made by ultrasonic vibrations resulted in a drastic reduction of the grinding normal force and surface roughness. In addition, the type of nanoparticles dispersed in water had a strong effect on the grinding tangential force. Hybrid Al2O3/graphite nanofluid through two different kinds of lubrication mechanisms—third body and slider layers—generated better lubrication than the other coolants, thereby having the lowest grinding forces and specific energy (40.13 J/mm3). It was also found that chemically exfoliating the graphene layers via oxidation and then purification prior to dispersion in water promoted their effectiveness. In conclusion, UV assisted MQL grinding increases operation efficiency by facilitating the material removal and reducing the use of coolants, frictional losses, and energy consumption in the grinding zone. Improvements up to 52%, 47%, and 61%, respectively, can be achieved in grinding normal force, specific energy, and surface roughness compared with conventional dry grinding.

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