Thermal properties of BaTiO3/Ag composites at different temperatures

This study examines the thermal properties, i.e. thermal expansion, specific heat, and thermal conductivity, of active composites comprising of barium titanate (BaTiO3) and silver (Ag). BaTiO3/Ag composites with varying silver composition were fabricated by powder metallurgy technique. The coefficient of thermal expansion (CTE) was measured within −50 to 250 °C temperature range using thermal mechanical analyzer (TMA). Differential scanning calorimeter (DSC) was used to measure the specific heat of the composites at a constant pressure within −50 to 200 °C temperature range, while, thermal conductivity and thermal diffusivity were measured by HotDisk technique. The effect of silver content on various thermal properties was investigated experimentally and numerically. The experimental results were also compared with some available experimental data from literature. As for the numerical investigations, 2-D and 3-D micromechanical models were constructed from realistic and randomly generated microstructures in order to predict the effective CTE and thermal conductivity of the composite, and investigate the local field fluctuations. The micromechanical models were implemented in finite elements. The effects of loading direction, porosity, particle shape and dispersion, and material properties of constituents were also studied. Numerical results for 2-D micromechanical models and 3-D generated microstructural models were compared to the experimental data.