Experimental and computational analyses of lead zirconate titanate reinforced glass matrix composites for structural applications

The mechanical reliability of glass matrix composites depends on the properties of the composite constituents, e.g. matrix and reinforcement. In many cases, microstructural variables, such as the volume fraction of the reinforcing secondary phase, the crystallographic anisotropy of the involved materials, and the physical coupling between the underlying thermodynamic fields, influences the macroscopic mechanical behaviour, in particular fracture toughness. In this paper, the mechanical properties of lead silicate glass matrix composites reinforced with 30wt% lead zirconate titanate (PZT) ferroelectric particles were studied. The samples were fabricated by hot pressing, and characterized by means of SEM, X-ray diffraction, DTA, and Vickers' indentation techniques. For this material, the stress fields at the tip of an advancing crack should be able to re-orient the ferroelectric domains in the PZT inclusions, inducing local crack-arrest, thus contributing to an increase of the macroscopic fracture toughness. Microstructural effects, such as crack-particle interactions were analysed using a FEM-based numerical approach. A good agreement between predicted crack propagation patterns and those obtained experimentally by the indentation technique was found. Numerical and experimental results suggest that traditional toughening mechanisms such as crack deflection, thermal cooling residual stresses, and load-transfer toughening are not active in the studied glass/PZT composites.