A novel method to fabricate curved piezoelectric composites with high piezoelectric phase volume fraction

Underwater acoustic transducer based on high piezoelectric phase volume fraction, large thickness, large area and curved piezoelectric composites (PC) possess wider beam width, higher source level and better directivity. However, the curved PC with large size is difficult to fabricate. The preparation of curved PC with large size and high piezoelectric phase volume fraction is even more tricky. The reported methods have risks of depolarization, deformation and poor periodicity and are not suitable for preparing PC with high piezoelectric phase volume fraction and large thickness. In this work, we proposed a novel fabrication method of the shaped-mold-assisted dice and fill technology. The 1–3 PC with high piezoelectric ceramic volume fraction of 80 %, thickness of 4.3 mm and area of 340 mm × 77 mm and the 2-2 PC with high piezoelectric ceramic volume fraction of 89.5 %, thickness of 5 mm and area of 262 mm × 20 mm were fabricated. The piezoelectric coefficient d₃₃ and relative constant stress permittivity ε₃₃^T/ε₀ of 1–3 and 2-2 PCs were comparable to piezoelectric phase itself. In addition, both 1–3 and 2-2 PCs exhibited a favorable performance consistency. This method solved the problem of limited cutting depth of thin blade, realizing PC with the structure of high piezoelectric phase volume fraction (＞ 70 %) and large thickness (＞ 3 mm) and eliminates the risk of depolarization, deformation and poor periodicity. This work enabled the potential for achieving large area, high piezoelectric phase volume and special-shaped PCs, which offers new ideas for designing innovative acoustic transducers and facilitates the progress of acoustic sensing technology.