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The study presents the results of the development of low-noise broadband hydrophone based on molecular electronic technology (MET) for mineral exploration systems in transit zones and on the shelf to depths of about 100 meters. The study investigates amplitude-frequency response (AFR), self-noise, dynamic range, and stability of sensor characteristics. The paper provides the results of experimental studies of prototypes in a laboratory and natural conditions in the Kara sea, including a comparison with hydrophones cable telemetry system ARAM ARIES II based on bottom receivers PZ dual sensor GS-PV-1S. The prototypes of MET hydrophones demonstrated a low level of selfnoise—below the Wenz model in the low-frequency region up to 48 dB concerning 1 µPa/√Hz—the possibility of obtaining qualitatively new seismic information in the lowfrequency region, a good signal-to-noise ratio, a wide dynamic range, and linearity of response. The research shows that the characteristics of the MET hydrophone signals in the main frequency band (from 1 to 300 Hz) are not inferior to the characteristics of the reference sensor signals. [ABSTRACT FROM AUTHOR]

42CrMo4 steel tubes are subjected to multiple induction heat treatments to obtain various hardened layer depths after spray water quenching. Current frequency, induction unit power and coil movement velocity along the tube axis are under consideration. The hardened layer depth is estimated along the transverse direction of the tubes using metallographic studies and microhardness measurements. An empirical equation is obtained for the hardened layer depth as a function of the induction heat treatment parameters. The laboratory test results are employed to develop the technology of the production of 42CrMo4 steel tubes designed for rotary percussive drilling equipment. The service life of induction hardened tubes during abrasive wear resistance field tests is approximately twice as long as that of conventionally nitrided ones. [ABSTRACT FROM AUTHOR]