Thermal theory of hydrodynamic lubrication in hydraulic extrusion in the presence of high-intensity longitudinal ultrasonic vibrations

The present study examines the microstructural evolution and mechanical properties of AZ91 magnesium alloy solidified under high intensity ultrasonic treatment (UST). High intensity ultrasonic vibrations were introduced isothermally below the liquidus temperature into the solidifying AZ91 alloy for the refinement of primary α-Mg grains and β-Mg17Al12intermetallic phase.Various microstructures were produced using different intensity of ultrasonic vibration at a constant temperature and fixed duration of UST. Without any ultrasonic treatment, the structure contains dendrites of primary α-Mg phase which are coarser and non-uniform in size. Nearly uniform, equiaxed grains with continuous and uniform network of intermetallic phase segregated along the grain boundaries were obtained in alloy subjected to high intensity ultrasonic vibration. The average grain size in this case decreased drastically from 300 μm for (without UST) to 17 μm (with UST at intensity of 4 kW/cm2). Vickers hardness also increased steadily with increase in ultrasonic intensity. The mechanisms for microstructural refinement are discussed and it is concluded that the fine uniform grain structure achieved under ultrasonic vibrations is attributed to the cavitation and the acoustic flow induced by ultrasonic vibrations.

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Study of coagulation efficiency of highly dispersed particles under the influence of high intensity ultrasonic vibrations

Journal of Physics Conference Series ◽

10.1088/1742-6596/1679/2/022013 ◽

2020 ◽

Vol 1679 ◽

pp. 022013

Author(s):

V N Khmelev ◽

V A Nesterov ◽

A V Shalunov ◽

A S Bochenkov ◽

P P Tertishnikov

Keyword(s):

High Intensity ◽

Ultrasonic Vibrations ◽

Dispersed Particles ◽

Highly Dispersed ◽

Highly Dispersed Particles

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ASSESSMENT OF IRON ORE CONCENTRATION CHARACTERISTICS ON THE BASIS OF ULTRASONIC MEASUREMENTS

Sustainable Development of Mountain Territories ◽

10.21177/1998-4502-2021-13-2-273-280 ◽

2021 ◽

Vol 13 (2) ◽

pp. 273-280

Author(s):

Vladimir MORKUN ◽

◽

Vitalii TRON ◽

Oleksandra SERDIUK ◽

Alona HAPONENKO ◽

...

Keyword(s):

High Intensity ◽

Iron Ore ◽

Simulation Modelling ◽

Spatial Process ◽

Technological Equipment ◽

Ultrasonic Vibrations ◽

High Intensity Ultrasound ◽

Concentration Plant ◽

Magnetic Concentration ◽

Controlling Actions

A great number of various factors to a different extent impact iron ore treatment, properties of mineral composition of ore and parameters of technological equipment being some of them. To solve the problem of improving performance of a concentration plant in terms of the concentrate, it is required to elaborate effective scheduled procedures, upgrade technological equipment, develop methods of control over concentration processes considering technological properties of ore fed. There is suggested a method of improving efficiency of magnetic concentration of iron ore under the action of high-intensity ultrasound. There are established dependencies between physical-mechanical and chemical-mineralogical characteristics of iron ore slurry solids and their behavior in technological flows under controlled ultrasonic vibrations, this enabling simulation modelling of the process and specification of optimal controlling actions. The research object is assessment of characteristics and control of iron ore magnetic concentration on the technological line of the ore concentration plant. The research subject is the cyber-physical system based on using impacts of highintensity ultrasound on slurry solids to assess characteristics of iron ore magnetic concentration. Obtained dependencies and mathematical models of the non-linear spatial process of high-intensity ultrasound propagation in the iron ore slurry enable implementing the method of assessing characteristics of iron ore magnetic concentration and due to this increase efficiency of the mentioned operations. There are suggested methods of calculating intensity of high-intensity ultrasound in a certain point of the measurement area in order to perform forecast displacement of ground ore particles and changes of the fraction composition of slurry solids under the controlled action of high-intensity ultrasonic vibrations. The developed method and the software-engineering complex for its implementation enable restoring a function of distributing ground ore particles by sizes, forecasting results of technological operations and forming controlling actions.

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A New High Intensity Grid Cap for RCA-EMU-3 Electron Microscopes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100101323 ◽

1968 ◽

Vol 26 ◽

pp. 316-317

Author(s):

George Christov ◽

Bolivar J. Lloyd

Keyword(s):

Electron Beam ◽

Electron Microscope ◽

High Voltage ◽

High Intensity ◽

Electron Gun ◽

Tungsten Filament ◽

Fluorescent Screen ◽

Electron Microscopes ◽

Pass Through ◽

Ground Potential

A new high intensity grid cap has been designed for the RCA-EMU-3 electron microscope. Various parameters of the new grid cap were investigated to determine its characteristics. The increase in illumination produced provides ease of focusing on the fluorescent screen at magnifications from 1500 to 50,000 times using an accelerating voltage of 50 KV.The EMU-3 type electron gun assembly consists of a V-shaped tungsten filament for a cathode with a thin metal threaded cathode shield and an anode with a central aperture to permit the beam to course the length of the column. The cathode shield is negatively biased at a potential of several hundred volts with respect to the filament. The electron beam is formed by electrons emitted from the tip of the filament which pass through an aperture of 0.1 inch diameter in the cap and then it is accelerated by the negative high voltage through a 0.625 inch diameter aperture in the anode which is at ground potential.

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