A novel method of evaluating surface properties of tempered glasses by the ultrasonic microspectroscopy technology

We discussed a method of evaluating surface compressive layer of tempered glasses by the ultrasonic microspectroscopy (UMS) technology. Chemically tempered glass specimens and the non-tempered specimen were prepared. Velocities of leaky surface acoustic wave (LSAW) and leaky surface skimming compressional wave (LSSCW) were measured by the line-focus-beam ultrasonic material characterization system. LSAW and LSSCW Velocities increased drastically caused by the surface compressive stress. Velocity differences caused by the difference of chemical strengthening process conditions were successfully detected. Resolution to depth of compressive stress layer by the LSAW velocity measurement was ±0.11 μm. Frequency characteristics of LSAW velocity have possibility of evaluating elastic properties distributions in the depth direction of tempered layer. Velocities changes were mainly caused by elastic constants changes by the bulk acoustic properties measurements.