Mechanical and Electromechanical Properties of Tetragonal ZrO₂ Fiber/PZT Composites

Abstract

Tetragonal ZrO₂ fiber/PZT composites were fabricated by slip casting and normal sintering in order to improve mechanical properties of PZT. With increasing fiber content from 0 to 20vol%, green densities increased from 57 to 63%, but fired densities decreased from 97.5 to 89.1%. Anisotropic shrinkage due to orientation of the fibers in casting occurred during firing. Mechanical properties were measured on the unpoled composites by applying the load in the direction perpendicular to the fiber orientation. In spite of the considerable decrease in fired density, bending strength of the composites remained at a constant value of 80MPa. On the other hand, fracture toughness K_IC increased from 0.91 to 1.29MPa⋅m^1/2. The composites were poled by applying a DC field in the direction perpendicular to the fiber orientation. Addition of fibers reduced both permittivity and electromechanical coupling factor k₃₁ in the tetragonal ZrO₂ fiber/PZT systems like in the monoclinic ZrO₂ fiber/PZT systems.