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1
Content available Material Ultrasonic Attenuation Influence on Conventional Ultrasonic Non-Destructive Copper Alloy Cast Testing
Koňár R., Mičian M.
Archives of Metallurgy and Materials
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2019
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Vol. 64, iss. 1
353--357
EN
Internal casting defects that are detected by radiography may also be detected by ultrasonic method. Ultrasonic testing allows investigation of the cross-sectional area of a casting, it is considered to be a volumetric inspection method. The high frequency acoustic energy travels through the casting until it hits the opposite surface or an interface or defect. The interface or defect reflects portions of the energy, which are collected in a receiving unit and displayed for the analyst to view. The pattern of the energy deflection can indicate internal defect. Ultrasonic casting testing is very complicated in practice. The complications are mainly due to the coarse-grain structure of the casting that causes a high ultrasound attenuation. High attenuation then makes it impossible to test the entire volume of material. This article is focused on measurement of attenuation, the effect of probe frequency on attenuation and testing results.
2
Content available Ultrasonic Inspection Techniques Possibilities for Centrifugal Cast Copper Alloy
Konar R., Mician M.
Archives of Foundry Engineering
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2017
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Vol. 17, iss. 2
35--38
EN
The article deals with ultrasonic testing possibilities of the copper alloy centrifugal casts. It focused on the problems that arise when testing of castings is made of non-ferrous materials. Most common types of casting defects is dedicated in theoretical introduction of article. Ultrasonic testing technique by conventional ultrasound system is described in the theoretical part too. Practical ultrasonic testing of centrifugal copper alloy cast - brass is in experimental part. The experimental sample was part of centrifugally cast brass ring with dimensions of Ø1200x34 mm. The influence of microstructure on ultrasonic attenuation and limitations in testing due to attenuation is describes in experimental part. Conventional direct single element contact ultrasound probe with frequencies of 5 MHz, 3.5 MHz and 2 MHz were used for all experimental measurements. The results of experimental part of article are recommendations for selecting equipment and accessories for casting testing made of non-ferrous metals.
3
Content available remote Acoustical investigations of uranium chalcogenides
Singh R. K., Pandey K. K., Singh M. P., Singh R. P.
Materials Science Poland
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2009
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Vol. 27, No. 4/1
1041--1053
EN
Ultrasonic attenuation due to phonon-phonon interaction and thermoelastic loss was evaluated in uranium chalcogenides viz. UX, X= S, Se, Te in fcc phase in the temperature range 50-600 K for longitudinal and shear waves along the <100>, <110> and <111> directions of propagation. Electrostatic and Born-Mayer repulsive potentials were used to obtain second and third order elastic constants, taking the nearest neighbour distance and hardness parameter as the input data. Second and third order elastic constants (obtained at various temperatures) were used to obtain the Gruneisen parameters and non-linearity or anisotropy parameters, which in turn were used to evaluate the ultrasonic attenuation coefficient over the frequency square due to phonon-phonon interaction, (?/f 2)p-p in the Akhiezer regime. It has been found that at lower temperatures ?/f 2 increases rapidly with temperature, and at higher temperatures the rate of increase becomes small. Contribution to the total attenuation due to thermoelastic loss is negligible in comparison with that of phonon-phonon interaction, i.e. a major part of the energy from the sound wave is removed, due to interaction of acoustic phonons with thermal phonons (lattice vibrations).
4
Detection of structural transformations in magnetic fluids for biomedical application by ultrasound
Józefczak A.
Molecular and Quantum Acoustics
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2008
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Vol. 29
121-133
EN
Acoustic spectroscopy has been used to investigate the effect of surface-coating layers in biocompatible magnetic fluids. The method applied is sensitive to structural changes in the suspension as the ultrasonic attenuation is correlated with the concentration of particles and the particle size distribution. The structural characteristics (aggregation phenomena) of the magnetic fluids with a single and double layer of a surfactant on magnetic field sweep have been analyzed on the basis of ultrasound attenuation measured for different frequencies of the acoustic wave.
5
Detection of structural transformations in magnetic fluids for biomedical application by ultrasound
Józefczak A.
Molecular and Quantum Acoustics
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2007
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Vol. 28
137-149
EN
Acoustic spectroscopy has been used to investigate the effect of surface-coating layers in biocompatible magnetic fluids. The method applied is sensitive to structural changes in the suspension as the ultrasonic attenuation is correlated with the concentration of particles and the particle size distribution. The structural characteristics (aggregation phenomena) of the magnetic fluids with a single and double layer of a surfactant on magnetic field sweep have been analyzed on the basis of ultrasound attenuation measured for different frequencies of the acoustic wave.
6
Ultrasonic Determination of The Aggregate Sizes Distribution Function In Water-Based Magnetic Liquid
Hornowski T.
Molecular and Quantum Acoustics
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2005
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Vol. 26
97-103
EN
An external magnetic field applied to a magnetic fluid gives rise to spherical and chain-like clusters or aggregates. In the present paper the determination of the aggregate sizes distribution function using ultrasonic spectroscopy is described. The results of the measurements of ultrasonic attenuation in a water-based magnetic fluid in the frequency range 3.5-40 MHz for three temperatures are presented. The interpretation of the obtained results is given.
7
The Broadband Ultrasonic Absorption in the Water-Based Magnetic Liquid as a Function of the Magnetic Field Strength
Hornowski T.
Molecular and Quantum Acoustics
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2004
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Vol. 25
109-114
EN
The results of the broadband ultrasonic absorption in a water-based magnetic fluid EMG- 605 are presented. Experimental results are analyzed using concept of the resonance absorption of an ultrasonic wave in a magnetic fluid acted on by a magnetic field. The size of the clusters as a function of the magnetic field strength are determined.
8
Investigations of Magnetic Properties of Apg 513a Magnetic Fluid
Hornowski T., Skumiel A., Łabowski M.
Molecular and Quantum Acoustics
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2004
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Vol. 25
115-120
EN
Static magnetic properties of magnetic fluid APG 513A have been measured. The differential magnetic susceptibility was measured as a function of an external magnetic field in the range of 1-200 kA/m, parallel to the direction of the field. The data were analysed using the Langevin equation and taking into account polydispersity of a system. A lognormal function was used as to approximate the distribution function of the size of magnetic particles. On the basis of the least-square fit of the susceptibility data to the Langevin equation the parameters of the distribution function as well as macroscopic parameters of the ferrofluid such as the initial susceptibility, saturation magnetization and particle number density were obtained. In magneto-granulometric analysis of the ferrofluid the mean magnetic diameter and standard deviation of particles were obtained. The agreement between the susceptibility data and the Langevin equation predictions is very good, which suggests the lack of interactions between particles and the absence of agglomerates in the ferrofluid studied.
9
The Frequency Dependance of Ulrtadonic Attenuation in the Water-Based Magnetic Liquid in the Absence of a Magnetic Field
Hornowski T., Łabowski M., Skumiel A.
Molecular and Quantum Acoustics
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2003
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Vol. 24
41-46
EN
The measurements of ultrasonic attenuation in a water-based magnetic fluid EMG-605 as a function of frequency are presented. Experimental results are analyzed using two-phase model of magnetic liquid. A good agreement between experimental data and the predictions of theoretical model was obtained.
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