Evaluation of glass materials by using the line-focus-beam ultrasonic-material-characterization system

We developed experimental procedures to evaluate glass materials using the line-focus-beam ultrasonic-material-characterization (LFB-UMC) system. We prepared 28 specimens of a commercial borosilicate glass from random lots, and measured the velocities of leaky-surface acoustic waves (LSAWs) and leaky-surface-skimming compressional waves (LSSCWs), VLSAW and VLSSCW, using V(z) curve measurements at 225 MHz and 23 degrees C. The velocities for VLSAW ranged from 3121.83 m/s to 3149.77 m/s, with a maximum deviation of 27.94 m/s. The velocities for VLSSCW ranged from 5547.7 m/s to 5585.0 m/s, with a maximum deviation of 37.3 m/s. To investigate these observed variations in VLSAW and VLSSCW, we measured the bulk acoustic wave (BAW) properties, viz., longitudinal and shear velocities, then the densities and the chemical compositions of 8 of the 28 specimens. The LFB-UMC measurements confirmed that decreases in VLSAW and VLSSCW occur mainly with the B2O3 dopant concentrations, corresponding to the decrease of shear-wave and longitudinal-wave velocities that are caused by the decrease of the stiffness constants c44 and c11, respectively, rather than with decreased densities. The sensitivities are -6.36 x 10(-2) wt%/(m/s) for VLSAW and -4.87 x 10(-2) wt%/(m/s) for VLSSCW. This demonstrates that the LFB-UMC system is effective for evaluating glass materials and controlling production processes, by analyzing variations in chemical composition through the super-accurate velocity measurements of LSAWs and LSSCWs.