The processes of ultrasonic elastic wave interaction with conduction electrons in metals were investigated by a new technique-microwave (MW) sensor. The authors obtained practical application results in the nondestructive testing (NDT) of metal objects in the static and motion mode.

The present paper describes theoretically and experimentally the possibility of such electron gas interaction with low-frequency ultrasonic waves, which the authors determine as a newly revealed phenomenon or even discovery, changing the physical concept of metal destruction processes and metal ageing. In contrast to previous experiments in determining surface cracks by MW method, the author has produced new experimental data in identifying invisible metal defects, i.e. active defects. Although the described method is based on the well-known Acoustic Emission (AE) method, there are significant differences. Firstly, according to calculations and experiment results the propagation speed of active defects generated by this new method is close to the speed of light. Secondly, in contrast to single AE events, occurring under conditions of excessive mechanical force, displayed signals in this new method can be detected during a time-interval excluding an additional mechanical load. Finally, the non-contact detection of dangerous defects, i.e. active defects, indicates the advantageous aspect of this new method to the contact AE method. This paper presents experimental data, sustaining the possible practical application of an advanced remote indicator of active defects (RIAD) as a diagnostic technique for steam railway car wheels in motion mode, testing reliability parameters of rotating turbine blades and operating sucker rod pumps.

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Abstract-Keywords-Microwave imaging method non-destructive testing of metals, the «Gorbunov» effect reactivation of samples, the indication of defects in the metal.

The results of experimental studies of millimeter waves backscattering with a frequency of 33 GHz by lithium niobate crystals using an installation based on a Doppler radar (microwave sensor) are presented. The measurements were carried out when ultrasonic vibrations with a frequency of 50.3 kHz were excited in the crystals and in their absence. It is found that due to elastic ultrasonic vibrations in the crystals, the phase modulation of the reflected wave from the crystal-dielectric-metal system occurs, as a result of which the effect of non-reciprocity of backscattering occurs. Detection of the phase difference between the voltage of the backscattering wave and the voltage of the incident (radiated) wave gave a useful signal level up to 50 dB higher than the noise level of the receiving and transmitting path of the microwave sensor. We established experimentally that the amplitude and frequency of the maximum of the envelope of the backscattering spectral components depends on the angle between the crystal symmetry axes and the vector polarization of the incident electromagnetic wave and on the orientation of the crystal in space. These measurements provide qualitative information about the piezoelectric properties of the crystal material and the presence of elastic waves. Keywords: Nonreciprocal backscattering, lithium niobate crystals, ultrasonic vibrations, Doppler radar, phase detection.