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Three composite materials with different CaZrO3/MgO fractions (2/3, 1/2, 1/3) and two single-phase materials (CaZrO3 and MgO) were fabricated and their thermal conductivity was investigated. Complete thermal and mechanical characterizations (thermal expansion coefficient, thermal diffusivity, specific heat, hardness and toughness) of the materials were performed. Values of the thermal conductivity up to 480 °C of the composites were compared with those calculated with the main analytical models. From the real microstructures of the three composites, representative volume elements (RVE) were built and used for finite element modelling (FEM) of thermal conductivity using conductivities of the single-phase materials as inputs. The FEM results showed no differences for the 3 spatial directions of the RVE, nor for the different edge lengths (11, 14 and 17 μm). Results of all analytical models are statistically different from the experimental ones, being those from the Bruggeman model the closest. Results of the proposed FEM are statistically coincident with the experimental ones, showing sensitivity to temperature variation.

Starting from synthetic raw materials (CaZrO3 and MgO), microstructural and mechanical properties were optimised in order to obtain dense multiphasic ceramic, then finite element method (FEM) of an equimolar (1:1) CaZrO3-MgO composite was performed in order to obtain the effective elastic modulus. Composite presents two main phases of orthorhombic CaZrO3 (81.5 wt.%) and cubic MgO (18.5 wt.%); For 1500 °C, relative density of 99.9%, characteristic strength of 168 MPa, hardness of 7.8 MPa and toughness of 2.5 MPa.m1/2 were obtained. FEM simulation was performed using two representative volume elements (RVE’s) with edge lengths of 14 μm (933 grains) and 17 μm (1670 grains), using isotropic elastic model, and anisotropic on specific set of crystallographic planes. The results of FEM using isotropic approach for the two RVE’s are perfectly aligned with the experimental (245 GPa), while the anisotropic model shows a difference of 6.5%.

In this work a methodology to reconstruct three-dimensional microstructures, representative of real biphasic ceramics using Neper free software is proposed. Finite element analysis in Ansys was implemented in order to calculate the effective elastic modulus of the simulated microstructures. Fine grained and dense zirconia toughened alumina (ZTA) materials with 5 and 40 vol.% of Yttria Stabilized Zirconia (YTZP) have been chosen to validate the proposed methodology. First, the effects of the size of the representative volume elements (RVEs) and the characteristics of the grain shapes are analysed. Second, the compliance with the isotropic condition is also verified. Agreement between the numerical and experimental values of the elastic modulus of the considered ZTA materials has been found. For these materials, zirconia fractions higher than 10 vol.% lead to bi-continuous microstructures which make the elastic properties deviate from the Voigt limit due to the increased number of contacts between zirconia grains.