Piezoelectric paints: preparation and application as built-in vibration sensors of structural materials

Piezoelectric paints were prepared using lead zirconate titanate (PZT) ceramic powder as a pigment and epoxy resin as a binder. The obtained paints were spread on the surface of an aluminium beam and cured at room temperature, thus forming the final thin films having thicknesses of 35–81 m and PZT volume fractions of 25%–53%. The thin films were then poled under electric fields of up to 350 kV cm^–1 at room temperature, and the resulting piezoelectric activity was evaluated from vibration measurements on the aluminium beam. Although not strictly quantitative, the piezoelectric activity of the thin film showed a tendency to increase with an increase in the film thickness and the PZT volume fraction. From the standpoint of the thin film application as built-in vibration sensors, the piezoelectric activity was confirmed to be high enough to determine the natural frequencies and mode shapes of the aluminium beam.