漏えい表面波速度測定によるセラミックス表層部の非破壊特性評価

概要

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Sintered ceramics often have different properties at the near surface from in the middle. With surface waves of different frequency or wavelength, we can estimate the depth-dependent subsurface properties, because the surface wave propagates in surface layer of about one wavelength. In this paper, the leaky surface wave velocities of Si_3N_4 ceramics with various porosity have been measured by a scanning acoustic microscope at 195 and 440 MHz and by time-of-flight measurement with a PVDF line focused sensor at 36 MHz. The velocities measured at 440 MHz are much higher than those at 36MHz, while the latter are very close to the Rayleigh wave velocities calculated with bulk velocities measured at 5 MHz. This shows elastic constant near surface is higher than that in the middle.
一般社団法人日本機械学会の論文
1997-11-25