Self-sensing metallic material based on PZT particles produced by friction stir processing envisaging structural health monitoring applications

Structural Health Monitoring (SHM) of metal parts is becoming increasingly important in structural applications. However, embedding real-time sensors such as fibre Bragg gratings and piezoceramics can negatively impact the mechanical properties of the hosting metal part. To address this issue, a new Self-Sensing Material (SSM) based on lead zirconate titanate (PZT) micro-particles has been developed. Through Friction Stir Processing, PZT micro-particles were embedded in aluminium parts, and their impact on the metal parts electrical and mechanical properties was assessed. Another approach was to embed barium titanate (BT) micro-particles in metal parts. The impact of PZT particles in aluminium parts was compared to SSM based on BT particles in this study. The SSM based on PZT particles showed a higher sensitivity than the SSM based on BT particles and processed aluminium. The inclusion of PZT particles improved the mechanical strength and decreased the electrical conductivity of the aluminium parts. The SSM based on PZT particles had a sensibility of 18.0×10−4μV/MPa and could detect solicitations with different frequencies, with the best performance observed under low-frequency solicitations. Additionally, EBSD, EDS, XRD and XPS analysis confirmed the existence of the PZT particles in aluminium parts. These results are promising and guarantee an increase in sensorial properties and the ability to self-monitor metal parts.