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Design and manufacture of piezoceramic semi-spherical caps for hydrophone applications

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Mateus Mota Morais
Total Authors: 1
Document type: Master's Dissertation
Press: São Carlos.
Institution: Universidade de São Paulo (USP). Escola de Engenharia de São Carlos (EESC/SBD)
Defense date:
Examining board members:
Carlos Alberto Fortulan; Cesar Renato Foschini; Maria Aparecida Pinheiro dos Santos
Advisor: Carlos Alberto Fortulan

Hydrophones are sensors that convert underwater acoustic vibrations energy into an electrical signal. Despite having several strategic civilian and military applications, currently, hydrophones are not produced in Brazil on a commercial base. Furthermore, they are difficult to import when foreign suppliers presume a potential military application. This master research aims to collaborate with the Brazilian Navy Research Institute (IPqM) in the development of national hydrophones that use spherical piezoceramics. This dissertation presents the development of the manufacturing process of Lead Titanate Zirconate (PZT) semispheres through isostatic pressing, followed by green machining. The IPqM defined as design requirements: external diameter 100 ± 0.8 au; thickness 5.9 ± 0.4 au and high and homogeneous density (> 95%). A preliminary mold for isostatic pressing at 200 MPa was designed and manufactured. The semispheres were green machined on a CNC abrasive machining bench. Due to the thin wall thickness-to-diameter relation, there was great potential for density gradients in the compacted part to introduce critical deformations during sintering. Therefore, the pressing process was simulated by the finite element method in ABAQUS software using the Drucker-Prager/cap constitutive model experimentally calibrated for the PZT powder. The simulation accurately predicted the shape and density of the pressed parts and assisted in the execution of optimized mold design. The parts were sintered and analyzed at IPqM for dimensions, chemical composition, and resulting microstructure. With the data obtained, a second mold for pressing was manufactured with the corrected dimensions. The semispheres produced in the second version of the mold presented dimensional accuracy (diameter 99.6 ± 0.2 au, thickness 5.7 ± 0.1 au) and high density (97.8%), meeting the design requirements. The project was successful in achieving the objective of developing and documenting the manufacturing process of hollow PZT semispheres thorough isostatic pressing and green machining for application in national hydrophones. (AU)

FAPESP's process: 18/07928-2 - Study of the homogeneity of isostatic pressing of piezoceramic hyperspherical caps and planning of external green machining
Grantee:Mateus Mota Morais
Support type: Scholarships in Brazil - Master