フェライト中の超音波伝播速度と弾性常数

概要

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Ultrasonic wave propagation velocity in ferrite which had been hardly researched was measured. With 5MC ultrasonic wave, velocities of longitudinal and transvers waves were measured by the rotating method in which the angle of total reflection of incident beam upon the sample was measured. From experimental values the elastic constant of ferrite was calculated. The results are summarized as follow: (1) Elastic constant of ferrites increases with increasing fired temperature. This consists with its shrinkage in firing at higher temperature than 1100°C. (2) The elastic constant of Ni-Zn ferrite increases steeply between 1100°C and 1200°C in firing. This trend corresponds to that of firing temperature vs. apparent density data and firing temperature vs. micro Vickers hardness data. (3) The elastic constant of ferrite does not change remarkably above and below the Curie temperature. (4) Changing the condition of producing ferrite, the elastic constants of ferrites varies by 10-20%. (5) It seems that additions for improving magnetic characters of ferrite bring the increase of the elastic constant by 10%. (6) Through the ferrites fired at high temperature runs the sound wave with its velocity more than 7000m/sec generally.
社団法人粉体粉末冶金協会の論文