Quantitative acoustic microscopy of anodized and coated aluminium at frequencies up to 1 GHz

The characterization of oxide layers in adhesive joints using ultrasonic reflection measurements

“…It would therefore be possible to inspect a joint to determine, for exam ple, whether anodization had been carried out. It is possible to use measurements in an acoustic microscope at frequencies up to 1 GHz to characterize oxide layers of the type found in adhesive joints (Sklar et al 1995) but these measurements cannot be carried out through any significant adherend thickness and so could not be used on real joints. In contrast, a 3.5 (im thick oxide layer having properties similar to those of the oaa layer tested here would readily be detectable at the frequencies used in this investigation.…”

Nondestructive Testing for Environmental Degradation of Adhesive Joints

“…However this method is more complicated due to the transversely isotropic nature of the interlayer. This makes the modeHing of the response of the interlayer to oblique incident waves more difficult and this is being looked at in more detail in a separate project [9]. Previous work carried out at Imperial College had identified a 32° shear wave incident in alumirrum as being the most sensitive to changes in the properties of the interlayer benefit of being beyond the longitudinal critical angle which means that there are fewer reflections received from the specimen.…”

Adhesive/Adherend Interlayer Property Measurement by Acoustic Microscopy

“…The technique of quantitative acoustic rnicroscopy has been used to gain information on physical properties in previous work [1]. The method does not provide a practical nondestructive test for adhesive joints since it requires the oxide layer tobe at the surface, but it provides information about the properlies which must be measured in a practical test.…”