Precise measurements of bulk-wave ultrasonic velocity dispersion and attenuation in solid materials in the VHF range

Abstract

A general method was established for precisely measuring velocity dispersion and attenuation in solid specimens with acoustic losses in the very high frequency (VHF) range, using the complex-mode measurement method and the diffraction correction method. Experimental procedures were presented for implementing such a method and demonstrated this measurement method in the frequency range of 50-230 MHz, using borosilicate glass (C-7740) as a dispersive specimen and synthetic silica glass (C-7980) as a nondispersive standard specimen. C-7980 exhibited no velocity dispersion; velocity was constant at 5929.14 +/- 0.03 m/s. C-7740 exhibited velocity dispersion, from 5542.27 m/s at 50 MHz to 5544.47 m/s at 230 MHz with an increase of about 2 m/s in the measured frequency range. When frequency dependence of attenuation was expressed as alpha = alpha(0)f(beta), the results were as follows: alpha0 = 1.07 x 10(-16) s2/m and beta = 2 for C-7980 and alpha0 = 5.16 x 10(-9) s(1.25)/m and beta = 1.25 for C-7740.

Frequency dependence of acoustic properties of aqueous glucose solutions in the VHF/UHF range

“…1 The system has further been improved to measure the amplitude and phase of radio frequency ͑rf͒ tone burst signals in the VHF range. 7,8 The experimental configuration for measurements is illustrated schematically in Fig. 5, in which a specimen is inserted between the parallel surfaces of synthetic silica (SiO 2 ) buffer rods having ZnO piezoelectric film transducers on their outer ends.…”

“…The gap length between the two buffer rods is determined by measuring frequency characteristics of the interference output of V 1 and V 2 for pure water of which the velocity is used as the reference. 1 The velocity is obtained by the complex-mode velocity measurement method, 7,8 in which the phase of the transducer output V 1 and V 2 is measured as a function of frequency. From the measured phase difference ͑0ϽϽ2 ͒ between V 1 and V 2 , the velocity is obtained as…”

An Evaluation of Effective Radiuses of Bulk-Wave Ultrasonic Transducers as Circular Piston Sources for Accurate Velocity Measurements

“…We have been attempting to detect experimentally the diffraction effects in the VHF range and to develop correction methods for them for more precisely measuring sound velocity at higher frequencies [10]. We also have developed a complex-mode measurement method [10] and a general measurement method for dispersive specimens [11], and we successfully have obtained detailed information on velocity dispersion useful for materials research.…”

Ultrasound-based density determination via buffer rod techniques: a review

“…As long as the beam spreading does not reach the dimensions of the receiver diameter, the principles of MRM for plane wave propagation are valid without correction. While the correction of diffraction in the far field is discussed by several authors (Papadakis, 1959;Papadakis et al, 1973;Kushibiki et al, 2003), the near-field problem is often not mentioned at all. Although the beam is assumed to be parallel in the near field (Povey and McClements), it is recommended to avoid it totally.…”

“…Moreover, investigations regarding the transducers type or piezoelectric materials (PEM) have not been found so far. It is known that the very different properties of the PEM result in completely different probe types (Lach et al, 1996). Concerning the determination of the reflection coefficient, different transducers constructed with different PEM might show different sensitivities and variance.…”