27-11-2012, 02:36 PM
Ultrasonics
Ultrasonics is a term meaning the application of ultrasound. It is often used in industry as a shorthand term for any equipment employing ultrasonic principles.
Ultrasonics is also a trade term coined by the Ultrasonic Manufacturers Association and used by its successor, the Ultrasonic Industry Association, to refer to the use of high-intensity acoustic energy to change materials [reference required and evidence of earliest usage of this term]. This usage is contrasted to ultrasound, which is generally reserved for imaging, as in sonar, materials examination (NDI), and diagnostics (mammography, duplex ultrasonography, etc.). The term "ultrasonic" is, however, common to both fields, for example
• Ultrasonic Flaw Detection for Technicians, 3rd ed., 2004 by J. C. Drury
• Ultrasonic nondestructive evaluation : engineering and biological material characterization, Boca Raton, FL : CRC Press, c2004, by Tribikram Kundu
Ultrasonication offers great potential in the processing of liquids and slurries, by improving the mixing and chemical reactions in various applications and industries. Ultrasonication generates alternating low-pressure and high-pressure waves in liquids, leading to the formation and violent collapse of small vacuum bubbles. This phenomenon is termed cavitation and causes high speed impinging liquid jets and strong hydrodynamic shear-forces. These effects are used for the deagglomeration and milling of micrometre and nanometre-size materials as well as for the disintegration of cells or the mixing of reactants. In this aspect, ultrasonication is an alternative to high-speed mixers and agitator bead mills. Ultrasonic foils under the moving wire in a paper machine will use the shock waves from the imploding bubbles to distribute the cellulose fibres more uniform in the produced paper web, which will make a stronger paper with more even surfaces. Furthermore, chemical reactions benefit from the free radicals created by the cavitation as well as from the energy input and the material transfer through boundary layers. For many processes, this sonochemical (see sonochemistry) effect leads to a substantial reduction in the reaction time, like in the transesterification of oil into biodiesel. Ultrasonication can easily be tested in lab scale for its effect on various liquid formulations. Equipment manufacturers have developed a number of larger ultrasonic processors of up to 16 kW power.[1] Therefore volumes from 1mL up to several hundred gallons per minute can be sonicated today in order to achieve all kinds of results from the link that is shown below.
Ultrasonic technology was for over 40 years employed in the steel industry, initially with flaw detection and later joined by wall thickness measurement.
For the past 15 years the plastics industry has used ultrasonic testing in the field of wall thickness measurement of pipe extrusions.
Ferromagnetic materials have following properties:
• In ferromagnetic materials, the magnetic lines of forces due to the applied magnetic field are strongly attracted towards the material.
• All ferromagnetic materials become paramagnetic above a temperature called Curie temperature Tc
• Permeability is greater than 1.
• Magnetic susceptibility is large and positive.
• Magnetic susceptibility decreases with the rise in temperature according to Curie-Weiss law.
• Ferromagnetism is the property of a material to be strongly attracted to a magnetic field and to become a powerful magnet.
• The source of ferromagnetism is the spin of the electrons.
• Ferromagnetic materials like Fe, Co, Ni, have incomplete inner shells. These shells can be completed by using Hund’s rule.
• When the specimen of a ferromagnetic material is magnetized by gradually increasing the magnetising fields, then the change of magnetic flux through the material is not continuous but in small discrete steps. Along the steep portion of the M-H magnetization curve, the discontinuous rotation of the magnetic domains give rise to Barkhauszen effect.
Ultrasonics is a term meaning the application of ultrasound. It is often used in industry as a shorthand term for any equipment employing ultrasonic principles.
Ultrasonics is also a trade term coined by the Ultrasonic Manufacturers Association and used by its successor, the Ultrasonic Industry Association, to refer to the use of high-intensity acoustic energy to change materials [reference required and evidence of earliest usage of this term]. This usage is contrasted to ultrasound, which is generally reserved for imaging, as in sonar, materials examination (NDI), and diagnostics (mammography, duplex ultrasonography, etc.). The term "ultrasonic" is, however, common to both fields, for example
• Ultrasonic Flaw Detection for Technicians, 3rd ed., 2004 by J. C. Drury
• Ultrasonic nondestructive evaluation : engineering and biological material characterization, Boca Raton, FL : CRC Press, c2004, by Tribikram Kundu
Ultrasonication offers great potential in the processing of liquids and slurries, by improving the mixing and chemical reactions in various applications and industries. Ultrasonication generates alternating low-pressure and high-pressure waves in liquids, leading to the formation and violent collapse of small vacuum bubbles. This phenomenon is termed cavitation and causes high speed impinging liquid jets and strong hydrodynamic shear-forces. These effects are used for the deagglomeration and milling of micrometre and nanometre-size materials as well as for the disintegration of cells or the mixing of reactants. In this aspect, ultrasonication is an alternative to high-speed mixers and agitator bead mills. Ultrasonic foils under the moving wire in a paper machine will use the shock waves from the imploding bubbles to distribute the cellulose fibres more uniform in the produced paper web, which will make a stronger paper with more even surfaces. Furthermore, chemical reactions benefit from the free radicals created by the cavitation as well as from the energy input and the material transfer through boundary layers. For many processes, this sonochemical (see sonochemistry) effect leads to a substantial reduction in the reaction time, like in the transesterification of oil into biodiesel. Ultrasonication can easily be tested in lab scale for its effect on various liquid formulations. Equipment manufacturers have developed a number of larger ultrasonic processors of up to 16 kW power.[1] Therefore volumes from 1mL up to several hundred gallons per minute can be sonicated today in order to achieve all kinds of results from the link that is shown below.
Ultrasonic technology was for over 40 years employed in the steel industry, initially with flaw detection and later joined by wall thickness measurement.
For the past 15 years the plastics industry has used ultrasonic testing in the field of wall thickness measurement of pipe extrusions.
Ferromagnetic materials have following properties:
• In ferromagnetic materials, the magnetic lines of forces due to the applied magnetic field are strongly attracted towards the material.
• All ferromagnetic materials become paramagnetic above a temperature called Curie temperature Tc
• Permeability is greater than 1.
• Magnetic susceptibility is large and positive.
• Magnetic susceptibility decreases with the rise in temperature according to Curie-Weiss law.
• Ferromagnetism is the property of a material to be strongly attracted to a magnetic field and to become a powerful magnet.
• The source of ferromagnetism is the spin of the electrons.
• Ferromagnetic materials like Fe, Co, Ni, have incomplete inner shells. These shells can be completed by using Hund’s rule.
• When the specimen of a ferromagnetic material is magnetized by gradually increasing the magnetising fields, then the change of magnetic flux through the material is not continuous but in small discrete steps. Along the steep portion of the M-H magnetization curve, the discontinuous rotation of the magnetic domains give rise to Barkhauszen effect.