Ultrasonic couplants for acoustic microscopy of low speed materials

摘要

A method is presented for estimating the compression wavenvelocities of organic fluids, based only on their density and molecularnproperties. The method is applied to a search for very low-speednultrasonic couplants, suitable for 250 MHz acoustic microscopy studiesnof epoxy materials. Experimental measurements confirmed that acousticnvelocity could be predicted within 3% for simple fluorine-containingnorganic compounds, and within 10% for those with a more complexnmolecular structure. The compound 2-dichloropentafluoropropane (C3nHCl2F5), with a compression wave velocity ofnCL=638 m/s and acceptably low attenuation coefficient, wasnidentified as a good coupling agent for acoustic microscopy studies ofnlow speed materials