| 摘要 |
PURPOSE:To increase the frequency of a probe and to reduce its size and to improve microdefect detection performance by fitting a screen type electrode on one surface of flat plate type piezoelectric ceramics and sticking a sound absorber on the opposite surface. CONSTITUTION:The screen type electrode 14 which is applied with a pulse voltage 13 from an ultrasonic flaw detector 21 is fitted on one surface of the flat plate type piezoelectric ceramic 12 and the sound absorber 15 which absorbs a generated ultrasonic wave is stuck on the opposite surface. Then, the end edges of the piezoelectric ceramic 12 and sound absorber 15 on a surface-wave advance side are cut into a slanting plane 17 so as to propagate a surface wave 11 to an object body 8 efficiently. Further, a surface wave 18 sent to the opposite side from the surface wave 11 about the screen type electrode 14 impedes flaw detection, so corner parts of the piezoelectric ceramics 12 are rounded into a curved surface 19, so that the surface wave advance around to the reverse surface without being reflected and is absorbed by the sound absorber 15 on the reverse surface. Consequently, the surface wave 11 is propagated efficiently on the surface of the object body 8 to detect a microdefect on or nearby the surface accurately.
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